The Dyeing of Woollen Fabrics
by Franklin Beech · English · Gutenberg #19985 · 560,581 chars · public domain (US)
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Title: The Dyeing of Woollen Fabrics
Author: Franklin Beech
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THE DYEING OF WOOLLEN FABRICS
by
FRANKLIN BEECH
Practical Colourist and Chemist;
Author of
"The Dyeing of Cotton Fabrics," Etc,
With Thirty-Three Illustrations
London
Scott, Greenwood & Son
8 Broadway, Ludgate Hill, E.C.
Canada: The Copp Clark Co., Ltd., Toronto
United States: D. Van Nostrand Co., New York
1902
[All rights remain with Scott, Greenwood & Son.]
PREFACE. (p. iii)
In this little book the author has endeavoured to supply the dyer of
woollen fabrics with a conveniently arranged handbook dealing with the
various branches of the wool dyeing industry, and trusts that it will
be found to meet the want which undoubtedly exists for such a book.
The text on which the book is based is expressed in the title "The
Dyeing of Woollen Fabrics," and in enlarging upon it the author has
endeavoured to describe clearly and in some detail the various
processes and operations generally, pointing out the principles
involved and illustrating these by numerous recipes, showing the
applications of a great variety of dyes in the production of the one
thousand and one tints and shades the wool dyer is called upon to
produce on the fabrics with which he is working. In pursuance of this
plan nothing is said of the composition and properties of the various
dyes, mordants, chemicals, etc., which are used. This is information
every wool dyer should possess, but the author believes it is better
dealt with in books devoted to Chemistry proper.
_May, 1902._
CONTENTS. (p. v)
CHAPTER I.
Page
THE WOOL FIBRE--
Structure, Composition and Properties...................... 1
CHAPTER II.
PROCESSES PREPARATORY TO DYEING--
Scouring and Bleaching of Wool............................ 15
CHAPTER III.
DYEING MACHINERY AND DYEING MANIPULATIONS--
Loose Wool Dyeing, Yarn Dyeing and Piece Dyeing
Machinery................................................. 40
CHAPTER IV.
THE PRINCIPLES AND PRACTICE OF WOOL DYEING--
Properties of Wool -- Methods of Wool Dyeing -- Groups
of Dyes --Dyeing with the Direct Dyes -- Dyeing with
Basic Dyes -- Dyeing with Acid Dyes -- Dyeing with
Mordant Dyes -- Level Dyeing -- Blacks on Wool -- Reds
on Wool -- Mordanting of Wool -- Orange Shades on Wool
-- Yellow Shades on Wool -- Green Shades on Wool --
Blue Shades on Wool -- Violet Shades on Wool -- Brown
Shades on Wool -- Mode Colours on Wool.................... 59
CHAPTER V.
DYEING UNION (MIXED COTTON AND WOOL) FABRICS............... 168
CHAPTER VI.
DYEING OF GLORIA........................................... 188
CHAPTER VII. (p. vi)
OPERATIONS FOLLOWING DYEING--
Washing--Soaping--Drying................................. 197
CHAPTER VIII.
EXPERIMENTAL DYEING AND COMPARATIVE DYE TESTING............ 211
CHAPTER IX.
TESTING OF THE COLOUR OF DYED FABRICS...................... 218
INDEX...................................................... 225
LIST OF ILLUSTRATIONS. (p. vii)
Fig. Page
1. Microscopical Sketch of Wool Fibre....................... 2
2. Kempy Wool Fibres........................................ 3
3. Sectional View of Wool Fibre............................. 4
4. Wool Fibres Showing Action of Alkalies.................. 10
5. Wool Fibres Showing Action of Acids..................... 11
6. Wool Washing Machine.................................... 20
7. Wool Cloth Washing Machine.............................. 28
8. Woollen Cloth Washing Machine........................... 29
9. Sulphur Bleach House.................................... 29
10. Dyeing Tubs and Vat..................................... 41
11. Section of Dye Vat...................................... 42
12. Delahunty's Dyeing Machine.............................. 44
13. Obermaier Dyeing Machine................................ 44
14. Holliday's Yarn Dyeing Machine.......................... 47
15. Klauder-Weldon Yarn Dyeing Machine...................... 47
16. Dyeing Jiggers for Cloth................................ 51
17. Dyeing Jiggers for Cloth................................ 53
18. Jig Winch Dyeing Machine................................ 53
19. Cloth Dyeing Machine.................................... 54
20. Plush Fabric Dyeing Machine............................. 55
21. Dye Beck for Cloth...................................... 56
22. Hawking Machine......................................... 57
23. Indigo Dye Vat for Cloth............................... 149
24. Squeezing Rollers...................................... 199
25. Yarn Washing Machine................................... 201
26. Cloth Washing Machine.................................. 202 (p. viii)
27. Cloth Washing Machine.................................. 204
28. Soaping and Washing Machine............................ 205
29. Hydro-extractor........................................ 206
30. Hydro-extractor........................................ 207
31. Yarn Drying Apparatus.................................. 208
32. Cloth Drying Machine................................... 208
33. Experimental Dye Apparatus............................. 212
CHAPTER I. (p. 001)
THE WOOL FIBRE.
Wool is one of the most important textile fibres used in the
manufacture of woven fabrics of all kinds. It belongs to the group of
animal fibres of which three kinds are met with in nature, and used in
the manufacture of textile fibres; two of these are derived from
quadruped animals, such as the sheep, goat, etc., while the third
class comprises the products of certain insects, _e.g._, silk.
The skin of all animals is covered with more or less of a fibrous
coat, which serves as a sort of protecting coat from the weather to
the skin underneath. Two different kinds of fibres are found on
animals; one is a stiff kind of fibre varying in length very much and
called hairy fibres, these sometimes grow to a great length. The other
class of animal fibres are the woolly fibres, short, elastic and soft;
they are the most esteemed for the manufacture of textile fabrics, it
is only when the hairy fibres are long that they are serviceable for
this particular purpose. There is a slight difference in the structure
of the two kinds of fibre, woolly fibres having a more scaly structure
than hairy fibres; the latter also differ in being more cylindrical in
form.
#Wool.#--By far the most important of the animal fibres is wool, the
fibre of the domestic sheep. Other animals, the llama or alpaca, the
Angora and Cashmere goats also yield fibres of a similar character,
which are imported under the name of wools. There are many (p. 002)
varieties of wools Which are yielded by the various breeds of sheep,
but they may be roughly divided into two kinds, according to the
length of "staple," as it is called. In the long-stapled wools the
fibres average from 7-1/2 to 9-1/2 inches in length, while the
short-stapled wools vary from 1 to 2 inches long. The diameter varies
very considerably from 0.00033 to 0.0018 of an inch.
[Illustration: Fig. 1.--Wool Fibre under the Microscope.]
Two varieties of thread are spun from wool, one is known as "worsted,"
the other as "woollen" yarns; from these yarns two kinds of cloths are
woven, distinguished as worsted and woollen cloths; the former are in
general not subjected to any milling or felting process, while the
latter invariably are.
#Physical Properties.#--When seen under the microscope the wool fibres
show a rod-like structure covered with broad scales, the edges of
which project from the body of the fibre, and all point in one
direction.
Fig. 1 shows typical wool fibres as viewed under the microscope; the
sketch shows very well the scales.
The shape of the scales varies in different breeds of wool. The (p. 003)
outer scales enclose inner medullary cells, which often contain
pigment matter. A transversed section of the wool fibre shows the
presence of a large number of cells. Sometimes wool fibres are
occasionally met with which have a peculiar white horny appearance;
these do not felt or dye well. They are known as "kempy" fibres. See
figure 2. The microscope shows that they are largely devoid of
structure, and are formed of very horny, impenetrable tissue, which is
difficult to treat in the milling or dyeing process.
[Illustration: Fig. 2.--Kempy Wool Fibres.]
The curly or twisted character of the fibre is caused by the unequal
contraction of the outer scales, and depends in a great measure upon
the hygroscopic nature of the wool. It may be entirely removed for the
time by wetting the wool in hot water, then drying it in a stretched
condition, or the curl may be artificially induced by unequal drying,
a fact which is turned to practical account in the curling of feathers
and of hair.
The amount of curl in different varieties of wool is very variable,
being as a rule greatest in the finer qualities, and diminishing as
the fibre becomes coarser. The diameter of the wool fibre varies (p. 004)
from 1/2000 to 1/5000 of an inch, and the number of curls from about
30 per cent. In fine wool as little as 1 or 2 per cent. in the thicker
fibres.
Elasticity and strength are properties which, in common with silk,
wool possesses in a greater degree than the vegetable fibres. When
submitted to strain the wool fibre exhibits a remarkable strength, and
when the breaking point is reached the fracture always takes place at
the juncture of two rings of the outer scales, the embedded edges of
the lower layer being pulled out of their seat. The scales themselves
are never broken.
[Illustration: Fig. 3.--Wool Fibre showing Medullary Centre.]
When first formed the cells are more or less of a spherical shape, and
contain a nucleus surrounded by the ultimate photoplasmic substance.
Those cells which constitute the core or central portion of the fibre
retain to some extent this original globular form and pulpy condition.
Surrounding this central portion or medulla, as it has been called
(see fig. 3), and forming the main bulk of the fibre, there is a
comparatively thick layer of partially flattened cells, which are also
elongated in the direction of the length of the fibre, and outside
this again there is a thinner stratum which may be compared to the
bark of a tree. This outer covering differs materially from the (p. 005)
rest of the fibre in its physical structure, but is, probably, nearly
identical with it, though possibly not entirely so, in chemical
composition. It consists of a series of flattened horny scales, each
being probably an aggregation of many cells. The scales, which have
been compared to the scales of a fish or to slates on a housetop,
overlap each other, the free edges protruding more or less from the
fibre, while the lower or covered edges are embedded and held in the
inner layer of cells. The free edges always point away from the root
of the fibre, just as do the bracts of a fir cone.
When viewing a section of a wool fibre there is, of course, no sharp
line of division between the three portions above described, but the
change from the central spherical cells to the elongated cellular
portion, and from these again to the flattened horny scales, is quite
gradual, so that the separation into zones, though well marked, is
very indefinite in respect of boundaries.
The scaly structure of wool is of great importance in regard to what
is known as felting property. When woollen fabrics are worked in
boiling water, especially in the presence of soap, they shrink in
length and breadth, but become thicker in substance, while there is a
greater amalgamation of the fibres of the fabric together to form a
more compact and dense cloth; this is due to the scaly structure of
the wool fibres enabling them to become entangled and closely united
together. In the manufacture of felt hats this is a property of very
great value.
#Variations in Physical Structure.#--Wool fibres vary somewhat amongst
themselves; fibres from different breeds of sheep, or even from
different parts of the same animal, vary greatly, not only in
thickness, length, etc., but also in actual structure. A typical wool
fibre, such as may be obtained a good merino or Southdown fleece, will
possess the typical structure described above, but frequently the type
is departed from to such an extent that the central core of (p. 006)
globular cells is entirely absent. Also the serrated character of the
outermost layer of cells reaches a much higher state of development in
some samples of wool than in others.
Wool is a much more hygroscopic fibre than cotton or any of the other
vegetable fibres, usually it contains about 18 per cent. of water, but
much depends upon the atmospheric conditions that prevail. This water
is contained in the wool in two forms: (1) as water of hydration
amounting to about 81 per cent., and (2) as hygroscopic water.
Experiments have shown that when a piece of dried wool is exposed to
an atmosphere saturated with water vapour it will absorb 50 per cent.
of its weight; cotton under the same conditions will take up 23 per
cent.; flax, 27·5 per cent.; jute, 28·5 per cent., and silk, 36·5 per
cent.
Heated to about 100° C. it parts with nearly the whole of its water
and becomes hard, horny and brittle, exposed to the air, the dry wool
again absorbs water and is restored to its former condition. When
heated to 100° C. wool becomes somewhat plastic, so that whatever form
is then imparted to it it will retain when it becomes cold, this
property is very useful in certain processes of finishing wool
fabrics, making hats, etc.
#Chemical Composition.#--In the natural or raw state each wool fibre is
surrounded by a considerable amount of foreign matter, so that in
treating of its chemical constitution it is necessary to distinguish
between pure wool and the raw fibre. The incrusting substance is
technically known as "Yolk," or "Suint," and is principally composed
of a kind of natural soap, consisting of the potash salts of certain
fatty acids, together with some fats which are incapable of
saponification.
The amount of yolk present upon different samples of wool varies
greatly, the finer varieties containing, as a rule, a larger
proportion than the coarser, and less valuable sorts.
The variation in the relative amount of pure fibres and yolk is (p. 007)
well shown in the following analyses which, however, do not by any
means represent extreme cases.
ANALYSES OF RAW MERINO WOOL. DRIED AT 100° C.
No. 1. No. 2.
Moisture 6·26 10·4
Yolk 47·30 27·0
Pure Wool 30·31 59·5
Dirt 11·13 3·1
------ ------
100·00 100·00
Yolk consists very largely of two complex substances which have been
termed wool perspiration and wool fat. The former is composed of the
potash salts of fatty acids, principally oleic and stearic acids; the
latter of the neutral carbohydrate, cholesterine, with other similar
bodies. The wool perspiration may be removed by a simple washing with
water, and on the Continent forms a valuable source of potash salts,
since the ash after ignition contains 70 to 90 per cent. of potassium
carbonate. The wool fat is insoluble in water, but dissolves readily
in ether, benzene, carbon disulphide, etc.
It is also removed from the wool by a treatment with alkali, and it is
not easy to explain the action in the case, since the wool fat is not
a glyceride, and will not form a soap, but is probably emulsified by
the wool perspiration.
#Chemical Composition of the Pure Fibre.#--The following analyses of
purified and dried wool fibre indicate its percentage composition:--
Mulder. Bowman.
Carbon 50·5 per cent. 50·8 per cent.
Hydrogen 6·8 " 7·2 "
Nitrogen 16·8 " 18·5 "
Oxygen 20·5 " 21·2 "
Sulphur 5·4 " 2·3 "
----- -----
100·0 100·0
It is sometimes stated that wool fibre consists of a definite (p. 008)
substance, keratine, but this view cannot now be admitted, since wool
appears to be composed of a mixture or combination of several very
complex substances. It is possible and even probable that the outer
epidermal scales have a somewhat different composition to the bulk of
the fibre, but whether that is the case or not is not known with any
degree of certainty, this much can be asserted, that wool is not a
simple definite chemical compound.
Sulphur is by far the most variable constituent of wool, sometimes as
little as 1·5 and occasionally as much as 5 per cent. being found. It
appears to be always present in two different forms, one portion being
in very feeble combination and easily removed by alkalies, the
remainder, which, according to Knecht, amounts to about 30 per cent.
of the total sulphur, cannot be removed without complete
disintegration of the fibre. This latter portion does not give a black
coloration with plumbite of soda.
The amount of ash left on incinerating dry wool varies from 1 to 2 per
cent., and some have considered this inorganic matter as an essential
constituent. It consists principally of salts of potassium, calcium
and aluminum, with, of course, sulphur.
The chemical composition of the wool fibre is evidently of a most
complicated nature; judging from its behaviour in dyeing it is evident
that it may contain two bodies, one of a basic character which enables
it to combine with the azo and acid series of dyes, the other possessing
acid characters enabling it to combine with the basic dyes of the magenta
and auramine type. Dr. Knecht has isolated from the wool fibre by
extraction with alkalies and precipitation with acids a substance to
which the name of lanuginic acid has been given. It is soluble in hot
water, precipitates both acid and basic colouring matters in the form
of coloured lakes. It yields precipitates with alum, stannous (p. 009)
chloride, chrome alum, silver nitrate, iron salts, copper sulphate. It
appears to be an albuminoid body. From its behaviour with the dyes,
and with tannic acid and metallic salts, it would appear that lanuginic
acid contains both acidic and basic groups. It contains all the
elements, carbon, hydrogen, oxygen, nitrogen and sulphur, found in
wool.
If wool is dyed in a dilute solution of Magenta (hydrochloride of
rosaniline), the whole of the base (rosaniline) is taken up, and the
whole of the acid (HCl) left in the bath, not, however, in the free
state, but probably as NH_{4}Cl, the ammonia being derived from the
wool itself. A further proof of the acid nature of lanuginic acid is
that wool may be dyed a fine magenta colour in a colourless solution
of rosaniline base; for since rosaniline base is colourless, and it
only forms a colour when combined with acids, the fibre has evidently
acted the part of an acid in the combination.
#Chemical Properties. Action of Alkalies.#--Alkalies have a powerful
action on wool, varying, of course, with the nature of the alkali,
strength of solution and temperature at which the action takes place.
An ammoniacal solution of copper hydroxide (Schweizer's reagent), has
comparatively little action in the cold, but when hot it dissolves
wool fairly readily.
The caustic alkalies; sodium hydroxide, NaOH, or potassium hydroxide
KOH, have a most deleterious action on wool. Even when very dilute and
used in the cold they act destructively, and leave the fibre with a
harsh feel and very tender, they cannot therefore be used for scouring
or cleansing wool. Hot solutions, even if weak, have a solvent action
on the wool fibre, producing a liquid of a soapy character from which
the wool is precipitated out on adding acids.
This action of alkalies has an important bearing on the scouring of
wool, for if this operation be not carried out with due care there (p. 010)
is in consequence great liability to impair the lustre and strength of
this fibre. From microscopical examination this effect of alkalies is
seen to be due to the fact that they tend to disintegrate the fibre,
loosen and open the scales, this is shown by contrasting the two
fibres A and B shown in figure 4, A being a normal wool fibre, B one
strongly treated with an alkali.
The alkaline carbonates have but little action on wool, none if used
dilute and at temperatures below 120° F.
[Illustration: Fig. 4.--Showing the Effects of Scouring Agents on the
Wool Fibre. A. Unscoured Fibre. B. Badly Scoured Fibre.]
Soap has practically no action on wool, and is therefore an excellent
scouring material for wool. The carbonate of ammonia is the best and
has the least action of the alkaline carbonates, those of potash and
soda if used too strong or too hot have a tendency to turn the wool
yellow, the carbonate of potash leaves the wool softer and more
lustrous than the carbonate of soda.
The influence of scouring agents on wool will be discussed in the
chapter on cleansing wool fabrics in more detail.
Caustic or quick-lime has a similar injurious action on the wool fibre
as the caustic alkalies.
#Action of Acids.#--Acids when dilute have but little influence on (p. 011)
the wool fibre, their tendency is to cause a separation of the scales
(see fig. 5) of the wool and so make it feel harsher. Strong acids
have a disintegrating action on the wool fibre. There is a very
considerable difference between the action of acids on wool and on
cotton, and this difference of action is taken advantage of in the
woollen industry to separate cotton from wool by the process commonly
known as "carbonising," which consists in treating the fabric with a
weak solution of hydrochloric acid or some other acid, then drying it;
the cotton is disintegrated and falls away in the form of a powder,
while the wool is not affected, sulphuric acid is used very largely in
dyeing wool with the acid- and azo-colouring matters.
[Illustration: Fig. 5.--Wool Fibre Heated with Acid.]
Nitric acid affects wool in a very similar manner to the acids named
above when used in a dilute form; if strong it gives a deep yellow
colour and acts somewhat destructively on the fibre.
Sulphurous acid (sulphur dioxide) has no effect on the actual fibre,
but exercises a bleaching action on the yellow colouring matter which
the wool contains, it is therefore largely used for bleaching (p. 012)
wool, being applied either in the form of gas or in solution in water;
the method will be found described in another chapter. Wool absorbs
sulphur dioxide in large amount, and if present is liable to retard
any subsequent dyeing processes.
#Action of Other Substances.#--Chlorine and the hypochlorites have an
energetic action on wool, and although they exert a bleaching action
they cannot well be used for bleaching wool. Hot solutions bring about
a slight oxidation of the fibre, which causes it to have a greater
affinity for colouring matters; advantage is taken of this fact in the
printing of delaines and woollen fabrics, while the woollen dyer would
occasionally find the treatment of service. A paper by Mr. E. Lodge,
in the _Journal of the Society of Dyers and Colourists_, 1892 (p. 41),
may be consulted with advantage on this subject. Wool treated with
chlorine loses its felting property, and hence becomes unshrinkable, a
fact of which advantage is taken in preparing unshrinkable woollen
fabrics.
When wool is boiled with solutions of metallic salts, such as the
sulphate of iron, chrome, aluminium and copper, the chlorides of tin,
copper and iron, the acetates of the same metals, as well as with some
other salts, decomposition of the salt occurs and a deposit of the
metallic oxide on the wool is obtained with the production of an acid
salt which remains in solution. In some cases this action is
favourably influenced by the presence of some organic acid or organic
salt, as, for examples, oxalic acid and cream of tartar (potassium
tartrate), along with the metallic salt.
On this fact depends the process of mordanting wool with potassium
bichromate, alum, alumina sulphate, ferrous sulphate, copper sulphate,
etc. The exact nature of the action which occurs is not properly
understood, but there is reason for thinking that the wool fibre has
the capacity of assimilating both the acid and the basic constituents
of the salt employed.
Excessive treatment with many metallic salts tends to make the (p. 013)
wool harsh to the feel, partly owing to the scales being opened out and
partly owing to the feel naturally imparted by the absorbed metallic
salt.
The normal salts of the alkaline metals, such as sodium chloride,
potassium sulphate, sodium sulphate, etc., have no action whatever on
the wool fibre.
Wool has a strong affinity for many colouring matters. For some of the
natural colours, turmeric, saffron, anotta, etc., and for the neutral
and basic coal-tar colours it has a direct affinity, and will combine
with them from their aqueous solutions. Wool is of a very permeable
character, so that it is readily penetrated by dye liquors; in the
case of wool fabrics much depends, however, upon the amount of felting
to which the fabric has been subjected.
If wool be boiled in water for a considerable time it will be observed
that it loses much of its beautiful lustre, feels harsher to the
touch, and also becomes felted and matted together. This has to be
carefully guarded against in all dyeing operations, where the handling
or moving of the yarns is apt to produce this unfortunate effect.
After prolonged boiling the fibre shows signs of slight decomposition,
from the traces of sulphuretted hydrogen and ammonia gases which it
evolves.
When wool is dried at 212° F. it assumes a husky, harsh feel, and its
strength is perceptibly impaired. According to Dr. Bowman, the wool
fibre really undergoes a slight chemical change at this temperature,
which becomes more obvious at 230° F., while at about 260° F. the
fibre begins to disintegrate. According to the researches of Persoz,
however, temperatures ranging from 260° F. to 380° F. can be employed
without any harm to the wool, if it has previously been soaked in a 10
per cent. solution of glycerine.
When wool is heated to 212° F. (100° Cent.) it becomes quite (p. 014)
pliant and plastic and may be moulded into almost any shape, which it
still retains when cold. This fact is of much interest in the
processes of finishing various goods, of embossing velvet where
designs are stamped on the woven fabric while hot, and in the crabbing
and steaming of woollen goods, making hats, etc.
CHAPTER II. (p. 015)
PROCESSES PREPARATORY TO DYEING, SCOURING AND
BLEACHING OF WOOL.
Wool scouring takes place at two stages in the process of manufacture
into cloth. First, in the raw state, to free the wool from the large
amount of grease and dirt it naturally contains; second, after being
manufactured into cloth, it is again scoured to free it from the oil
that has been added to the scoured raw wool to enable it to spin
easily. This oiling is generally known as wool batching, and before
the spun yarns or woven fabrics can be dyed it is necessary to remove
it.
Raw wool is a very impure substance, containing comparatively little
wool fibre, rarely more than 50 to 60 per cent. in the cleanest
fleeces, while it may be as low as 25 per cent. in the dirtiest.
First there is a small quantity of dirt; there is what is called the
suint, a kind of soapy matter, which can be removed by washing in hot
water. This soap has for its base potash, while its acids are numerous
and complex. The wool contains a fatty-like substance of the nature of
wax, called cholesterine, and this imparts to the fatty matter, which
be extracted from the wool fibre, very peculiar properties. Besides
these there are several other bodies of minor importance, all of which
have to be removed from the wool before it can be manufactured into
cloth.
Marker and Schulz give the following analysis of a good sample of (p. 016)
raw wool:--
Moisture 23·48 per cent.
Wool fat 7·17 "
Wool soap (suint), soluble in water 21·13 "
Soluble in alcohol 0·35 "
Soluble in ether 0·29 "
Soluble in dilute hydrochloric acid 1·45 "
Wool fibre 43·20 "
Dirt 2·93 "
------
100·00
Two principles underlie the methods which are in use for this purpose.
The first principle and the one on which the oldest method is based is
the abstraction of the whole of the grease, etc., from the wool by
means of an alkaline or soapy liquor at one operation. This cannot
nowadays be considered a scientific method. Although it extracts the
grease, etc., from the wool, and leaves the latter in a good condition
for after processes, yet with it one might almost say that the whole
of the soap or alkali used, as well as the wool grease itself, is lost
as a waste product; whereas any good process should aim at obtaining
the wool grease for use in some form or another. The second principle
which underlies all the most recent methods for extracting the grease
from the wool, consists in treating the fibre with some solvent like
benzol, carbon bisulphide, petroleum spirit, carbon tetrachloride,
etc., which dissolves out the cholesterine and any other free
fatty matter which is in the wool fibre, leaving the latter in such a
condition that by washing with water the rest of the impurities in the
wool can be extracted. By distilling off and recondensing the solvent
can be recovered for future use, while the wool fat can also be
obtained in a condition to use for various purposes. This is rather a
more scientific method than the old one, but it has not as yet come
into extensive use.
#Wool Scouring. Old Methods.#--In the early days of wool scouring (p. 017)
this operation was done in a very primitive fashion, generally in a
few tubs, which could be heated by steam or otherwise, and in which
wool was worked by means of hand forks. These primitive processes are
still in use in some small works, especially where the wool is dyed in
the loose condition, but in all the large works machinery has been
adopted, which machinery has been brought to a high state of
perfection, and does its work very well, and without much attendant
manual labour.
The alkaline substances used in this process of scouring demand some
notice. These comprise soda ash, soda crystals, caustic soda, silicate
of soda, potash, caustic potash, soaps of various kinds, stale urine,
ammoniacal compounds. Which of these may be used in any particular
case depends upon a variety of reasons. Potash is the best alkaline
agent to use. It agrees better with the fibre than any other, leaving
it soft and elastic. Ammonia is the next best, but it does not take
out the grease as well as the potash. Soda does not suit as well as
potash, as it has a tendency to leave the fibre harsh in feel and
somewhat brittle, yet on account of its being so much cheaper it is
the most largely used. The use of silicate of soda cannot be
recommended, as it has a great tendency to leave the fibre hard, which
may be ascribed to the deposition of silica on the fibre.
The caustic alkalies cannot be used as they have too solvent an action
on the fibre. The carbonates, therefore, in the form of soda ash or
potash, or pearl ash, are used, or better still, soap is used as it
has a greater solvent action on the fatty matter of the wool than have
the alkalies, and in this respect a potash soap is better than a soda
soap.
The character of the wool determines the alkali to be used; fine,
long-stapled wools, which are usually very free from grease in excess,
should always be treated with potash, or a potash soap, which will (p. 018)
remove the whole of the grease from the wool, leaving the latter in a
fine, soft, silky condition.
Short-stapled wools can be treated with soap and a little soda ash,
but too much of the latter is to be avoided. Coarse and greasy wools
may be scoured with soap and soda ash, or other alkali which is almost
necessary to remove the large amount of grease these wools contain.
Practically the only alkaline products now in use are the various hard
and soft soaps, and the carbonates of soda and potash in their various
forms of soda ash, soda crystals, potashes, pearl ash, etc. Ammonia
and its compounds are rarely used, while stale urine, which acts in
virtue of the ammonia it contains has practically gone out of use.
#Hand-Scouring.#--Wool scouring by hand is easily done and requires few
appliances, simple tubs or vats of sufficient capacity in which steam
pipes are placed, so that the scouring liquors can be heated up. The
best temperatures to use are about 130° to 140° F., and it is not
advisable to exceed the latter, as there is then some risk that the
alkali may act on the fibre too strongly.
The strength of the scouring liquor necessarily varies with the kind
of wool being treated, and with the kind of alkaline product used; if
soft, fine wools are being treated, then the liquor may be made with 1
to 2 lb. of soap to 10 gallons of water (if a mixture of soap and
alkali is used, then it may contain from 1/4 to 1/2 lb. soda ash, and
1/2 lb. to 1 lb. of soap). For coarse, greasy wools these quantities
may be increased by about one-half. The best plan of scouring by hand
is to treat the wool in a tub with a scouring liquor for about half an
hour, then to squeeze out the surplus liquor and to treat again in a
new liquor for half an hour; this liquor may be used for a new batch
of wool. The wool is often put into nets, and these are lifted up and
down in the liquor so as to cause it to penetrate to every part of the
wool.
It is not advisable to work the wool about too much, otherwise (p. 019)
felting might ensue and this must be avoided. The felting of the wool
is one of the troubles of the wool-scourer and is often difficult to
avoid, it is mostly brought about by excessive working of the wool
during the process, and by the use of too high a temperature in the
scouring bath. The remedies are obvious to the practical man, as
little handling of the wool as possible, and at as low a temperature
as possible. Still it is necessary to see that the scouring liquor
penetrates to every part of the wool which is being treated.
To ensure this, care must be taken not to scour too much at one time,
so that the wool is loosely placed in the scouring tub, if placed
loose in the latter, the workmen can by means of forks work it to and
fro while in process of treatment. After the wool has been through
these scouring liquors it is thrown on a scray to drain, and is next
placed in cisterns which have perforated false bottoms. In these
cisterns it is washed with cold water two or three times, the water
being run off from the wool between each washing; it is then spread
out in a room to dry. As a rule, a man can wash from 500 lb. to
600 lb. of wool in a day by this method. Another plan which is
sometimes adopted so as to avoid handling the wool as much as
possible, and thus prevent felting, is to place the wool in cages
having perforated sides which will hold about 1 cwt. of wool. They are
lowered by means of cranes into the washing liquors, and the wool in
them is then worked for a quarter of an hour, when the cages and their
contents are lifted out and the surplus liquor allowed to drain off.
They are then lowered into the next bath, treated or worked in this,
again lifted out and dropped into the wash waters.
There is by this plan a saving of handling, and more wool can be got
through in the same time, but it requires two men to work it. These
hand processes are only in use in small works, having been (p. 020)
replaced in all large works by mechanical methods described below.
#Machine Scouring.#--Wool-scouring machinery has been brought to a high
state of perfection by the successive efforts of many inventors, and
by their means wool washing has been much simplified and improved.
Wool-washing machinery is made by several firms, among whom may be
mentioned Messrs. J. & W. McNaught, and John Petrie, Junior, Limited,
both of Rochdale.
[Illustration: Fig. 6.--Wool-washing Machine.]
Fig. 6 shows one form of wool-washing machine. It consists of a long
trough which contains the scouring liquor. In this machine the wool
enters at the left-hand end, and is seized by a fork or rake and
carried forward by it a short distance, then another rake seizes it
and carries it further forward to another rake, and this to the last
rake of the machine, which draws it out of the machine to a pair of
squeezing rollers which press out the surplus liquor, and from these
rollers the scoured wool passes to a travelling band for delivery from
the machine. Sometimes the wool is not entered into the trough direct,
but is put on a travelling apron which opens it and delivers it in a
more open form into the trough. The movement of the forks causes some
degree of agitation in the scouring liquor which facilitates the
penetration of the liquor through the wool, and thus brings about a
better scouring.
After the wool has passed through the machine it is taken and run once
more through the machine. Some scourers use the same liquor, but it is
better to use fresh liquors, after which it is washed in the same
machine with water two or three times. With a single machine there is
some time and labour lost in transferring the wool from one end to the
other between the separate treatments, and in large works where a
great deal of wool is scoured it is usual to place three or four of
these machines end to end.
The first is filled with strong scouring liquor, the second with (p. 022)
a weaker liquor, while the third and fourth contains wash waters, and
the wool is gradually passed by the action of the machine through the
series without requiring any manual aid. Between each machine it is
passed through squeezing rollers as before, and finally emerges
thoroughly scoured. A good plan of working in connection with such a
series of machines is to have four as above, two washing machines and
two soaping machines, the soap liquor is run through these in a
continuous stream, entering in at the delivery end of the second
soaper and passing out at the entering end of the first soaper. The
wool as it first enters the machine comes into contact with rather
dirty soap liquor, but this suffices to rid it of a good deal of loose
dirt; as it passes along the machine it comes in contact with cleaner
and fresher soap liquor, which gradually takes all grease and dirt out
of it, and, finally, when it passes out it comes in contact with fresh
liquor, which removes out the last traces of dirt and grease. In the
same way it passes through the washers, being treated at the last with
clean water. By this plan the scouring is better done, while there is
some saving of soap liquor and wash water, for of these rather less is
required than by the usual system. These are matters of consideration
for wool scourers. The wool-washing liquors after using should be
stored in tanks to be treated for recovery of the grease which they
contain.
The temperature of the scouring liquors should be about 100° F.,
certainly not more than 120° F., high temperatures are very liable to
bring about felting, while tending to increase the harshness of the
wool, particularly when soda is the agent used. By this method all the
wool fat, suint, etc., of the wool find their way into the soap
liquors. These were formerly thrown away, but they are generally
treated with acid and the fat of the soap and wool recovered, under
the name of wool grease or Yorkshire grease. (_Vide_ G. H. Hurst, (p. 023)
"Yorkshire Grease," _Jour. Soc. Chem. Ind._, February, 1889.)
The wool fat consists largely of a peculiar fat-like body known as
cholesterine. This, however, is unsaponifiable, and cannot be made
into soap; at the same time when it gets into, as it does, the
recovered wool grease it spoils the latter for soap-making purposes.
Cholesterine has some properties which make it valuable for other
purposes; it is a stable body not prone to decomposition, it is
capable of absorbing a large quantity of water, and it is on these
accounts useful for medicinal purposes in the production of ointments,
and it might be useful in candle-making. When it gets into recovered
grease it cannot be extracted from it in an economical manner. The
wool suint consists largely of the potash soaps of oleic and stearic
acids. These two fatty acids find their way into the recovered wool
grease but the potash salts are lost, while they would be valuable for
various purposes if they could be recovered.
Another form of wool-washing machine has a frame carrying a number of
forks arranged transversely to the machine. The forks are by suitable
gearing given a motion which consists of the following cycle of
movements. The forks are driven forwards in the trough of the machine,
carrying the wool along with them, they are then lifted out, carried
back, and again allowed to drop into the machine, when they are ready
to go forward again. Thus the forks continually push the wool from one
end of the machine to the other.
It is a common plan to have three machines placed end to end, so that
the wool passes from one to the other; in a set of this kind the first
machine should have a capacity of 1,500 gallons or thereabouts, the
second 1,000 gallons, and the third 750 gallons.
#Wool Scouring by Solvents.#--Of late years processes have been (p. 024)
invented for the scouring of wool, either raw or spun by means of
solvents, like carbon bisulphide, benzol, petroleum spirit, etc. Such
processes are in a sense rather more scientific than the alkali
processes, for whereas in the latter the grease, etc., of the wool and
the oil used in batching it are practically lost for further use, and
therefore wasted, being thrown away very often, although they may be
partially recovered from the used scouring liquors, in the solvent
processes the grease and oil may be recovered for future use for some
purpose or other.
The great objection to these processes is the danger that attends
their use, owing to the inflammable character of the solvents. Several
other objections may be raised, some of which are mechanical, and due
to the want of proper machinery for carrying out the processes. There
are many ways in which solvents may be applied, some are the subject
of patents. It is not possible to describe the details of all these,
but two of the most recent will be mentioned.
In Singer's process, which was described in detail by Mr. Watson Smith
some time ago before the Society of Dyers and Colourists, carbon
bisulphide is used. The raw wool is placed between two endless bands
of wire, and it is carried through a series of troughs containing
bisulphide of carbon; during its passage through the troughs the
solvent takes out the grease, and loosens the other constituents of
the wool. After going through the bisulphide the wool is dried and
passed through water which completes the process. The carbon
bisulphide that has been used is placed in steam-heated stills,
distilled off from the grease, condensed in suitable condensers, and
used over again. In this process, with care, there is very little loss
of solvent. The grease which is recovered can be used for various
purposes, one of which is the manufacture of ointments, pomades, etc.
The disadvantages of bisulphide are: (1) It tends after some time (p. 025)
to cause the wool to acquire a yellow cast, due to the free
sulphur which it contains, and which being left in the wool gradually
causes it to turn yellow. By using redistilled bisulphide this defect
may be avoided. (2) Another defect is the evil odour of the solvent.
This, however, is less with redistilled bisulphide than with the
ordinary quality, and with suitable apparatus is not insuperable. (3)
Another defect is the volatility and inflammability of carbon
bisulphide. On the other hand, bisulphide possesses the very great
advantage of being at once heavier than, and insoluble in, water, and
it can be, therefore, stored under water very much more safely than
can any of the other solvents which are used.
Burnell's machine has two troughs filled with benzoline. In these are
arranged a large central roller round which are some smaller rollers.
The wool passes round the large roller and is subjected to a number of
squeezings in passing the smaller rollers. A current of the benzoline
is continually passing through the machine. The whole is enclosed in a
hood to avoid loss of solvent as far as possible. After passing
through the benzoline trough the wool passes through a similar trough
filled with water. Benzoline is better than carbon bisulphide in that
there is no tendency on the part of the wool to turn yellow after its
use, on the other hand it is more inflammable, and when it does take
fire is more dangerous, and being lighter than water is not so readily
and safely stored. Another feature is that it is not so completely
volatile at steam temperatures, so that a little may be left in the
grease and thus tend to deteriorate it. Coal-tar benzol, the quality
known as 90's, would be better to use.
The solvent processes are well worth the attention of wool scourers,
all that is required for their proper development being the production
and use of suitable machinery.
After the raw wool has been scoured it is batched, _i.e._, it is (p. 026)
mixed with a quantity of oil for the purpose of lubricating the
wool to enable it more easily to stand the friction to which it is
subjected in the subsequent processes of spinning and weaving by
giving it greater pliability.
For this purpose various kinds of oil are used. Olive oil is the
principal favourite, the variety mostly used being Gallipoli oil.
Ground-nut oil is also extensively employed, and is cheaper than
olive. Oleic acid a by-product of the candle industry, is extensively
used under the name of cloth oil, there is also used oleine, or wool
oil, obtained by the distillation of Yorkshire grease.
So far as merely oiling the wool is concerned there is not much to
choose between these different oils, olive perhaps works the best and
agrees best with the wool. Mineral oils have been and can be used
either alone or mixed with the oils above mentioned, and so far as
lubricating the wool is concerned do very well and are much cheaper
than the fatty oils named above.
The following are some analyses of various oils used as cloth oils
which the author has had occasion to analyse.
1. 2. 3. 4.
Specific gravity at 60° F. 0·9031 0·9091 0·6909 0·8904
Free fatty acid 55·02 64·42 51·52 68·05
Unsaponifiable oil 34·56 9·95 32·80 9·52
Saponifiable oil 10·32 25·32 15·68 12·43
------ ------ ------ ------
100·00 100·00 100·00 100·00
Nos. 1 and 2 are prepared from Yorkshire grease. The unsaponifiable
matter in these is purely natural, it will be seen it varies within
wide limits. Nos. 3 and 4 are made from the oleic acid of the candle
factories, and the unsaponifiable matter is due to their containing
mineral oil which has been added to them.
So far as regards the object for which the wool is oiled, the mineral
oils will answer almost as well as the fatty oils and with most (p. 027)
satisfactory results from an economical point of view, for they are
much cheaper. But this is not the only point to be considered. The oil
has to be got out of the wool before the latter can be dyed. Now while
the fatty oils can be easily removed, by treatment with soap, and they
can be recovered along with the fat of the soap, mineral oils cannot
be entirely removed from the wool, what remains in will interfere very
much with the satisfactory dyeing of the wool, and what is got out
finding its way into the covered wool grease, spoils this for soap
making and other uses, so that on the whole what is gained in lessened
cost of oiling is lost by the increased liability to defects in dyeing
and consequently depreciation in value of the wool, and to decrease in
value of the recovered grease.
The amount of oil used varies from 7 per cent. with the best wools to
15 per cent. with shoddy wools. The scouring agents generally used are
the same as those used in loose wool scouring, namely, carbonate of
soda for coarse woollen yarns, soap and soda for medium yarns, and
soap and ammonia for fine yarns. Prior to treating the yarns it is
best to allow them to steep in hot water at about 170° F. for twenty
minutes, then to allow them to cool. The actual scouring is often done
in large wooden tubs, across which rods can be put on which to hang
the hanks of yarn, and in which are placed steam pipes for heating up
the bath. The best temperature to treat the yarn at is about 150° F.;
too high a temperature must be avoided, as with increased heat the
tendency to felt is materially augmented, and felting must be avoided.
The hanks are treated for about twenty minutes in the liquor, and are
then wrung out, drained, and again treated in new scouring liquor for
the same length of time. After rinsing in cold water they are dried
and finished.
When the oiled wool has been spun into yarns, whether worsted or (p. 028)
woollen, and passes into the hands of the dyer, it is necessary to
remove from it all the oil before any dyeing operations can be
satisfactorily carried out. This oil is removed by the use of soap and
weak alkaline liquors, using these at about 110° to 120° F. The most
common way is to have the liquor in a rectangular wooden tank, and
hang the hank of yarn in by sticks resting on the edges of the tank;
from time to time the hanks are turned over until all the oil has been
washed out, then they are wrung out and passed into a tank of clean
water to wash out the soap, after which the yarn is ready for dyeing.
When the yarn is of such a character that it is liable to curl up,
shrink and become entangled, it is necessary that it be stretched
while it is being treated with the soap liquor; this is effected by a
stretching apparatus consisting of two sets of rollers connected
together by a screw attachment, so that the distance between the two
sets of rollers can be varied. The hanks are hung between each pair of
rollers, and can be stretched tightly as may be required.
For pressing out the surplus liquor from the hanks of yarn a pair of
squeezing rollers is used.
#Scouring Woollen Piece Goods.#--Very often before weaving the yarns are
not scoured to remove the oil they contain, as the weaving is more
conveniently done with oily yarn than with a scoured yarn. Before
dyeing the oil must be taken out of the pieces, and this can be
conveniently done by scouring in a washing machine such as is shown in
figures 7 and 8, using soap and soda liquors as before, and following
up with a good rinse with water.
[Illustration: Fig. 7.--Cloth-washing Machine.]
The soap liquors used in scouring yarns and pieces become charged with
oil, and they should be kept, and the oil recovered from them together
with the fatty matter of the soap, by treatment with sulphuric acid.
By subjecting the grease or fatty matter so obtained to a boil with
caustic soda soap is obtained which may be again used in scouring (p. 029)
wool.
[Illustration: Fig. 8.--Cloth-washing Machine.]
#Bleaching Wool.#--The wool fibre has to be treated very differently
from cotton fibre. It will not stand the action of as powerful
bleaching agents, and, consequently, weaker ones must be used. This is
a decided disadvantage, for whereas with cotton the colouring matter
is effectually destroyed, so that the bleached cotton never regains
its original colour, the same is not the case with wool, especially
with sulphur-bleached wool, here the colouring matter of the fibre is,
as it were, only hidden, and will under certain circumstances return.
The two materials chiefly used for bleaching wool are sulphur and
peroxide of hydrogen.
[Illustration: Fig. 9.--Sulphur Bleach House.]
#Sulphur Bleaching.#--Bleaching wool by sulphur is a comparatively (p. 030)
simple process. A sulphur house is built, the usual size being 12 feet
high by 12 feet broad, and about 17 feet long. Brick is the most suitable
material. The house should have well-fitting windows on two sides,
and good tight doors at the ends (see fig. 9). Some houses have a (p. 031)
small furnace at each corner for burning the sulphur, two of these
furnaces are fitted with hoods, so that the sulphur gases can be
conveyed to the upper part of the chamber, but a better plan, and one
mostly adopted where the chamber is used for bleaching pieces, is to
construct a false perforated bottom above the real bottom of the chamber,
the sulphur being burnt in the space between the two floors. If yarn
is being bleached the hanks are hung on wooden rods or poles in (p. 032)
the chamber, while with pieces an arrangement is constructed so that the
pieces which are stitched together are passed in a continuous manner
through the chamber.
When all is ready the chamber doors are closed, and the furnaces are
heated, some sulphur thrown upon them, which burning evolves sulphur
dioxide gas, sulphurous acid, and this acting upon the wool bleaches
it. The great thing is to cause a thorough circulation of the gas
through every part of the chamber, so that the yarn or pieces are
entirely exposed in every part to the bleaching action of the gas.
This is effected by causing the gas to pass into the chamber at
several points, and, seeing that it passes upwards, to the ventilator
in the roof of the chamber. Generally speaking, a certain quantity of
sulphur depending upon the quantity of goods being treated is placed
in the chamber and allowed to burn itself out; the quantity used being
about 6 to 8 per cent. of the weight of the goods. After the
sulphuring the goods are simply rinsed in water and dried.
Sulphur bleaching is not an effective process, the colouring matter is
not actually destroyed, having only entered into a chemical
combination with the sulphur dioxide to form a colourless compound,
and it only requires that the wool be treated with some material which
will destroy this combination to bring the colour back again in all
its original strength; washing in weak alkalies or in soap and water
will do this. Another defect of the process lies in sulphur being
volatilised in the free form, and settling upon the wool causes it to
turn yellow, and this yellow colour cannot be got rid of.
The goods must be thoroughly rinsed with water after the bleaching,
the object being to rid the wool of traces of sulphuric acid, which it
often contains, and which if left in would in time cause the
disintegration of the wool.
Sometimes the wool is washed in a little weak ammonia or soda (p. 033)
liquor, but this is not advisable, as there is too much tendency for
the colour of the wool to come back again, owing to the neutralising
of the sulphur dioxide by the alkali.
Instead of using the gas, the sulphur dioxide may be applied in the
form of a solution in water. The goods are then simply steeped for
some hours in a solution of the gas in water until they are bleached,
then they are rinsed in water and dried. In this method it is
important that the solution of the gas be freshly made, otherwise it
is liable to contain but little sulphurous acid, and plenty of
sulphuric acid which has no bleaching properties, but, on the other
hand, is liable to lead to damage of the goods if it be not washed out
afterwards.
A better method of utilising the bleaching action of sulphur in a
liquid form is to prepare a bath of bisulphite of soda, and acidify it
with hydrochloric acid, then to enter the wool, stirring well for some
time, and allowing it to steep for some hours, next to expose to the
air for a while, and rinse as before.
It is better to allow the wool to steep for about an hour in a simple
bath of bisulphite, then enter into a weak hydrochloric acid bath for
a few hours. The acid liberates sulphur dioxide in a nascent
condition, which then exerts a more powerful bleaching action than if
it were already free.
Even with liquid bleaching the bleach is not any more perfect than it
is with the gas bleaching; the colour is liable to come back again on
being washed with soap or alkali, although there is a freedom from the
defect of yellow stains being produced.
Goods properly bleached will stand exposure to air for some
considerable time, but those imperfectly bleached exhibit a tendency
to regain their yellow colour on exposure to air. One fault which is
sometimes met with in sulphur bleaching is a want of softness in (p. 034)
the wool, the process seeming to render the fibre harsh.
Washing in a little weak soft soap or in weak soda will remedy this
and restore the suppleness of the wool; at the same time care must be
taken that the alkaline treatment is not too strong, or otherwise the
bleaching effect of the sulphur will be neutralised as pointed out
above.
#Bleaching Wool by Peroxide of Hydrogen.#--During recent years there has
come into use for bleaching the animal fibres peroxide of hydrogen,
or, as the French call it, oxygenated water. This body is a near
relation to water, being composed of the same two elements, oxygen and
hydrogen; in different proportions in water these elements are
combined in the proportion of 1 part of hydrogen to 8 parts of oxygen,
while in the peroxide the proportions are 1 of hydrogen to 16 of
oxygen. These proportions are by weight, and are expressed by the
chemical formulæ for water H_{2}O, and for hydrogen peroxide
H_{2}O_{2}. Water, as is well known, is a very stable body, and
although it can be decomposed, yet it requires some considerable power
to effect it. Now the extra quantity of oxygen which may be considered
to have been introduced into water to convert it into peroxide has
also introduced an element of instability, the extra quantity of
oxygen being ever ready to combine with some other body for which it
has a greater affinity than for the water. This property can be
utilised in the bleaching industry with great advantage, true
bleaching being essentially a process of oxidation. The colouring
matter of the fibre, which has to be destroyed so that the fibre shall
appear white, is best destroyed by oxidation, but the process must not
be carried out too strongly, otherwise the oxidation will not be
confined to the colouring matter, but will extend to the fibre itself
and disintegrate it, with the result that the fibre will become
tendered and be rendered useless.
Peroxide of hydrogen is a weak oxidiser, and therefore, although (p. 035)
strong enough to destroy the colouring matter of the fibre is not
strong enough to decompose the fibre itself. Hydrogen peroxide is sold
as a water-white liquid, without any odour or taste. Its strength is
measured by the quantity of oxygen which is evolved when one volume of
the liquid is treated with potassium permanganate; the most common
strength is 10 volume peroxide, but 30 and 40 volume peroxide is made.
On keeping it loses its oxygen, so that it is always advisable to use
a supply up as quickly as possible.
Articles of all kinds can be bleached by simply placing them in a weak
solution of the peroxide, leaving them there for a short time, then
taking out and exposing to the air for some time. The best plan of
applying peroxide of hydrogen is the following: Prepare the bleaching
bath by mixing 1 part of peroxide with 4 parts of water. The strength
can be varied; for those goods that only require a very slight bleach
the proportions may be 1 to 12, while for dark goods the proportions
first given may be used. This bath must be used in either a wooden or
earthenware vessel. Metals of all kinds must be avoided, as they lead
to a decomposition of the peroxide, and therefore a loss of material.
To the bath so prepared just enough ammonia should be added to make it
alkaline, a condition that may be ascertained by using a red litmus
paper, which must just turn blue. Into the bath so prepared the
well-scoured goods are entered and worked well, so that they become
thoroughly saturated. They are then lightly wrung and exposed to the
air for some hours, but must not be allowed to get dry, because only
so long as they are moist is the bleaching going on; if they get dry
the goods should be re-entered into the bath and again exposed to the
air.
If one treatment is not sufficient the process should be repeated. The
peroxide bath is not exhausted, and only requires new material to (p. 036)
be added to it in sufficient quantity to enable the goods to be
readily and easily worked in the liquor. Any degree of whiteness may
be obtained with a sufficient number of workings. No further treatment
is necessary. It is found in practice that an alkaline bath gives the
best results.
Another plan of preparing the bleaching bath is to prepare a bath with
peroxide and water as before, then add to a sufficient quantity of a
solution of silicate of soda 4 parts of water to 1 of silicate of soda
at 100° Tw., to make the bath alkaline. Into this bath the goods are
entered and are then exposed to the air as before, after which they
may be passed through a weak bath of sulphurous acid, being next well
washed in water and dried.
The advantage of bleaching with peroxide is that, as it leaves only
water in the goods as the result of action, there is no danger of
their becoming tendered by an after development of acid due to
defective washing, as is the case with the sulphur bleach. The goods
never alter in colour afterwards, because there is nothing left in
that will change colour. Some bleachers add a little magnesia to the
bath, but this is not at all necessary.
#Bleaching with Peroxide of Soda.#--Peroxide of soda has come to the
front of late for bleaching wool. With it a stronger bleaching bath
can be made, while the product itself is more stable than peroxide of
hydrogen, only it is needful to keep it in tightly closed metal
vessels, free from any possibility of coming in contact with water or
organic matter of any kind, or accidents may happen. In order to
bleach 100 lb. of wool, a bath of water is prepared, and to this is
added 6 lb. of sulphuric acid and then slowly 4 lb. of peroxide of
sodium in small quantities at a time. Make the bath slightly alkaline
by adding ammonia. Heat the bath to 150° F., enter the wool and allow
to remain five to six hours, then rinse well and dry. If the (p. 037)
colour does not come out sufficiently white repeat the process.
THE CHLORINATION OF WOOL.
The employment of chlorine in wool dyeing and wool printing has of
late years received an impetus in directions previously little thought
of. The addition of a little chlorine to the decoction of logwood has
been recommended as increasing the dyeing power of the wool. Treating
the wool with chlorine has a material influence in increasing its
capacity for taking dye-stuffs, and although but little attention has
been paid to this circumstance by wool dyers, yet among wool printers
it has come largely into use, and enables them to produce fuller and
faster shades than would otherwise be possible.
The method involves the treatment of the wool first with an acid, then
with a solution of a hypochlorite. The staple becomes soft and supple
and assumes a silky character; in dyeing it shows a greater affinity
for the dyes than it did previously. Although not deteriorated in
strength, it almost entirely loses its felting properties. On account
of this feature the process cannot be adopted for wool which has to be
fulled, but it is of service where felting of the goods is to be
avoided, for worsteds, underwear, woollen and half woollen hosiery,
etc., in which the felting property that occurs on washing is rather
objectionable.
By the chloring of the wool the intensity of the shade dyed is
increased to such a degree that when dyeing with Acid black, Naphthol
black, Naphthol green, Nigrosine, Fast blue, Water blue, and some
others dyed in an acid bath, but little more than half the dye used on
unchlored wool is required, while with Induline, more even and intense
shades are obtained than is otherwise possible.
The operation of chlorination can be done either in one or two (p. 038)
baths. The choice depends upon circumstances and the judgment of the
dyer. The process by the two-bath method, with subsequent dyeing in
the second or separate bath is (for 100 lb. of wool), as follows. The
first bath contains, for light cloths, yarn, etc., from 3 to 4 lb.
sulphuric acid, 168° Tw., and for heavier cloths and felt, where the
penetration and equalisation of the colour is difficult, from 8 lb. to
10 lb. of acid. Generally speaking, a temperature of 170° to 175° F.
is sufficient, although for heavy wool and for wool with poor dyeing
qualities it is well to use the bath at the boil. The treatment lasts
for half an hour, in which time the acid is almost completely
absorbed.
The second bath contains a clear solution of 10 lb. bleaching powder,
which solution is prepared as follows. Dry bleaching powder of the
best quality is stirred in a wooden vat with 70 gallons of water, the
mass is allowed to stand, the clear, supernatant liquor is run into
the vat and the sediment stirred up and again allowed to settle, the
clear liquor being run off as before, and 5 gallons more water is run
in. The clear liquors of these three treatments are then mixed
together to form the chloring bath. Special care should be taken that
no undissolved particles of the bleaching powder should be left in,
for if these settle on the wool they result in too great a development
of chlorine, which injures the wool.
The goods after being in the acid bath are entered in this chlorine
bath at a temperature of 70° F., which is then raised to the boil. If
the acid bath has been strong, or been used at the boil, it is perhaps
best to rinse the goods before entering into the chlorine bath. The
hypochlorous acid disappears so completely from this bath that it may
at once be used as the dye-bath, for which purpose it is only necessary
to lift the goods, add the required amount of dye-stuff, re-enter the
goods and work until the bath is exhausted, which generally happens when
acid dyes are used. If a separate dye-bath be preferred, this is (p. 039)
made and used as is ordinarily done.
To perform all the operations in one bath the acid bath is made with
from 3 to 4 lb. sulphuric acid, and the wool is treated therein for
thirty minutes at 170° F., until all the acid has been absorbed. Then
the bath is allowed to cool down to 70° or 80° F., the clear bleaching
powder solution is added, the goods are re-entered, and the bath is
heated to the boil. When all the chlorine has disappeared add the
dye-stuff, and dye as directed above.
In printing on wool the chlorination of the wool is a most important
preliminary operation. For this purpose the cloth is passed for
fifteen minutes at 170° F. through a bath containing 3/4 oz. sulphuric
acid per gallon of water. Then it is passed through a cold bath of 3/4
oz. bleaching powder per gallon of water, after which the cloth is
rinsed and dried and is then ready for printing.
Another method of chloring the wool is to pass the goods through a
bath made with 100 gallons of water, 2 gallons hydrochloric acid and 2
gallons bleaching powder solution of 16° Tw. As some chlorine is given
off it is best to use this in a well-ventilated place.
CHAPTER III. (p. 040)
DYEING MACHINERY AND DYEING MANIPULATIONS.
Wool is dyed in a variety of forms, raw, loose wool; partly
manufactured fibre in the form of slubbing or sliver; spun fibres or
yarns, in hanks or skeins and in warps, and lastly in the form of
woven pieces. These different forms necessitate the employment of
different forms of machinery and different modes of handling, it is
evident to the least unobservant that it would be quite impossible to
subject slubbing or sliver to the same treatment as yarn or cloth,
otherwise the slubbing would be destroyed and rendered valueless.
In the early days all dyeing was done by hand in the simplest possible
contrivances, but during the last quarter of a century there has been
a great development in the quantity of dyeing that has been done, and
this has really necessitated the application of machinery, for hand
work could not possibly cope with the amount of dyeing now done.
Consequently there has been devised during the past two decades a
great variety of machines for dyeing every description of textile
fabrics, some have not been found a practical success for a variety of
reasons and have gone out of use, others have been successful and are
in use in dye-works.
#Hand Dyeing.#--Dyeing by hand is carried on in the simplest possible
appliances, much depends upon whether the work can be done at the
ordinary temperature or at the boil. Figure 10 shows round and oval
tubs and a rectangular vat much in use in dye-houses. These are (p. 041)
made of wood, but copper dye-vats are also made, these may be used
for all kinds of material--loose fibre, yarns or cloth. In the case of
loose fibre this is stirred about either with poles or with rakes,
care being taken to turn every part over and over and open out the
masses of fibre as much as possible in order to avoid matting or
clotting together. In the case of yarns or skeins, these are hung on
sticks resting on the edges of the tub or vat. These sticks are best
made of hickory, but ash or beech or any hard wood that can be worked
smooth and which does not swell much when treated with water may be
used. The usual method of working is to hang the skein on the stick,
spreading it out as much as possible, then immerse the yarn in the
liquor, lift it up and down two or three times to fully wet out the
yarn, then turn the yarn over on the stick and repeat the dipping
processes, then allow to steep in the dye-liquor. This is done with
all the batch of yarn that is to be dyed at a time. When all the yarn
has been entered into the dye-bath, the first stickful is lifted out,
the yarn turned over and re-entered in the dye-liquor; this operation
is carried out with all the sticks of yarn until the wool has become
dyed of the required depth. In the case of long rectangular vats it is
customary for two men, one on each side of the vat, to turn the yarns,
each man taking charge of the yarn which is nearest to him.
[Illustration: Fig. 10.--Dyeing-tubs and Vat.]
Woven goods may be dyed in the tub or vat, the pieces being drawn in
and out by poles, but the results are not altogether satisfactory, (p. 042)
and it is preferable to use machines for dyeing piece goods.
[Illustration: Fig. 11.--Dye-vat with Steam-pipe.]
Plain tubs or vats, such as those shown in figure 10, are used for
dyeing and otherwise treating goods in the cold, or at a lukewarm
heat, when the supply of hot water can be drawn from a separate
boiler. When, however, it is necessary to work at the boil, then the
vat must be fitted with a steam coil. This is best laid along the
bottom in a serpentine form. Above the pipe should be an open
lattice-work bottom, which, while it permits the free circulation of
boiling water in the vat, prevents the material being dyed from coming
in contact with the steam pipe. This is important if uniform shades
are to be dyed, for any excessive heating of any portion of the bath
leads to stains being produced on the material in that part of the
bath. Figure 11 shows a vat fitted with a steam pipe. That portion (p. 043)
of the steam pipe which passes down at the end of the vat is in a
small compartment boxed off from the main body of the vat, so that no
part of the material which is being dyed can come in contact with it.
A closed steam coil will, on the whole, give the best results, as then
no weakening of the dye-liquor can take place through dilution by the
condensation of the steam. Many dye-vats are, however, fitted with
perforated, or as they are called, open steam coils, in which case
there is, perhaps, better circulation of the liquor in the dye-vat,
but as some of the steam must condense there is a little dilution of
it.
DYEING MACHINES.
Dye-tubs and vats, such as those described above, have been largely
superseded by machines in which the handling or working of the
materials being dyed is effected by mechanical means. There have been
a large number of dyeing machines invented, some of these have not
been found to be very practical, and so they have gone out of use.
Space will not admit of a detailed account of every kind of machine,
but only of those which are in constant use in dye-works.
#Dyeing Loose or Raw Wool and Cotton.#--Few machines have been designed
for this purpose, and about the only successful one is
_Delahunty's Dyeing Machine._--This is illustrated in figure 12. It
consists of a drum made of lattice work which can revolve inside an
outer wooden casing. The interior of the revolving drum is fitted with
hooks or fingers, whose action is to keep the material open. One
segment of the drum is made to open so that the loose cotton or wool
to be dyed can be inserted. By suitable gearing the drum can be
revolved, and the dye-liquor, which is in the lower half of the wooden
casing, penetrates through the lattice work of the drum, and dyes (p. 044)
the material contained in it. The construction of the machine is well
shown in the drawing, while the mode of working is obvious from it and
the description just given. The machine is very successful, and well
adapted for dyeing loose or raw wool and cotton. The material may be
scoured, bleached, dyed or otherwise treated in this machine.
[Illustration: Fig. 12.--Delahunty's Dyeing Machine.]
The Obermaier Machine, presently to be described, may also be used for
dyeing loose cotton or wool.
[Illustration: Fig. 13.--Obermaier Dyeing Machine.]
#Dyeing Slubbing, Sliver or Carded Wool.#--It is found in practice that
the dyeing of loose wool is not altogether satisfactory, the
impurities they naturally contain interfere with the purity of the (p. 045)
shade they will take. Then again the dyes and mordants used in dyeing
them are found to have some action on the wire of the carding engine
through which they are passed; at any rate, a card does not last as
long when working dyed wools as when used on undyed cotton or wool
fibres. Yet for the production of certain fancy yarns for weaving some
special classes of fabrics it is desirable to dye the wool before it
is spun into thread. The best plan is undoubtedly to dye the fibre
after it has been carded and partly spun into what is known as
slubbing, or sliver. All the impurities have been removed, the wool
fibres are laid straight, and so it becomes much easier to dye. On the
other hand, as it is necessary to keep the sliver or slubbing straight
and level, no working about in the dye-liquors can be allowed to take
place, and so such must be dyed in specially constructed machines, and
one of the best of these is the
_Obermaier Dyeing Machine_, which is illustrated in figure 13.--In (p. 046)
the Obermaier apparatus dye-vat, A, is placed a cage consisting of an
inner perforated metal cylinder, C, and an outer perforated metal
cylinder, D; between these two is placed the material to be dyed. C is
in contact with the suction end of a centrifugal pump, P, the delivery
end of which discharges into the dye-vat A. The working of the machine
is as follows: the slubbing or sliver is placed in the space between C
and D rather tightly, so that it will not move about. Then the inner
cage is placed in the dye-vat as shown. The vat is filled with the
dye-liquor, which can be heated up by a steam pipe. The pump is set in
motion, the dye-liquor is drawn from A to C, and in so doing passes
through the material packed in B and dyes it. The circulation of the
liquor is carried on as long as experience shows to be necessary. The
dye-liquor is run off, hot water is run in to wash the dyed material,
and the pump is kept running for some time to ensure thorough rinsing,
then the water is run off, and by keeping the pump running and air
going through a certain amount of drying can be effected. This machine
works very well, and with a little experience constant results can (p. 047)
be obtained. The slubbing or sliver may be scoured, bleached, rinsed,
dyed, washed, soaped, or otherwise treated without removing it from
the machine, which is a most decided advantage.
[Illustration: Fig. 14.--Read Holliday's Yarn-dyeing Machine.]
#Yarn Dyeing Machines.#--In figure 14 is given an illustration of a
machine for dyeing yarn in the hank form, made by Messrs. Read
Holliday & Sons, of Huddersfield. The illustration gives a very good
idea of the machine. It consists of a wooden dye-vat, which can be
heated by steam pipes in the usual way. Extending over the vat are a
number of reels or bobbins, these are best made of wood or enamelled
iron. These reels are in connection with suitable gearing, so that
they can be revolved. There is also an arrangement by means of which
the reels can be lifted bodily in and out of the dye-vat for the
purpose of taking on and off the hanks of yarn. A reel will hold about
2 lb. of yarn. The working of the machine is simple. The vat is filled
with the requisite dye-liquor. The reels which are lifted out of the
vat are then charged with the yarn, which has been previously wetted
out. They are then set in revolution and dropped into the dye-vat, and
kept there until it is seen that the yarn has acquired the desired
shade. The reels are lifted out and the hanks removed when the machine
is ready for another lot of yarn.
There are several makers of hank-dyeing machines of this type, and as
a rule they work very well. The only source of trouble is a slight
tendency for the yarn on one reel if hung loosely of becoming
entangled with the yarn on other reels. This is to some extent
obviated by hanging in the bottom of the hank a roller, which acts as
a weight and keeps the yarn stretched and so prevents it flying about.
To some makes of these machines a hank wringer is attached.
[Illustration: Fig. 15.--Klauder-Weldon Dyeing Machine.]
_Klauder-Weldon Hank-dyeing Machine._--This is illustrated in (p. 048)
figure 15, which shows the latest form. It consists of a
half-cylindrical dye-vat built of wood. On a central axis is built two
discs or rod carriers, which can revolve in the dye-vat, the
revolution being given by suitable gearing which is shown at the side
of the machine. On the outer edge of the discs are clips for carrying
rods on which one end of the hanks of yarn is hung, while the other
end is placed on a similar rod carrier near the axle. The revolution
of the discs carries the yarn through the dye-liquor contained in the
lower semi-cylindrical part of the machine previously alluded to. (p. 049)
At a certain point in every revolution of the discs the rods carrying
the yarns are turned a little; this causes the yarn to move on the
rods, and this motion helps to bring about greater evenness of dyeing.
The most modern form of this machine is provided with an arrangement
by means of which the whole batch of yarn can be lifted out of the
dye-liquor. Arrangements are made by which from time to time fresh
quantities of dyes can be added if required to bring up the dyed yarn
to any desired shade. This machine works well and gives good results.
Beyond the necessary labour in charging and discharging, and a little
attention from time to time as the operation proceeds, to see if the
dyeing is coming up to shade, the machine requires little attention.
Many other forms of hank-dyeing machine have been devised. There is
Corron's, in which an ordinary rectangular dye-vat is used. Round this
is a framework which carries a lifting and falling arrangement that
travels to and fro along the vat. The hanks of yarn are hung on rods
of a special construction designed to open them out in a manner as
nearly approaching hand work as is possible. The machine works in this
way. The lifting arrangement is at one end of the vat, the hanks are
hung on the rods and placed in the vat. Then the lifter is set in
motion and moves along the vat; as it does so it lifts up each rod
full of yarn, turns it over, opening out the yarn in so doing, then it
drops it again in the vat. When it has travelled to the end of the vat
it returns, packing up the rods of yarn in so doing, and this motion
is kept up until the dyeing is completed. This machine is very
ingenious.
A type of machine which has been made by several makers consists of an
ordinary rectangular dye-vat surrounded with a framework carrying a
number of sets of endless chains, the links of which carry fingers.
The hanks of yarn are hung on rods at one end of which is a tooth (p. 050)
wheel that when in position fits into a rack on the side of the vat.
The action of the machine is this, the hanks are hung on the rods and
placed at the entrance end of the vat, by the moving of the chains it
is carried along the vat and at the same time revolves, thus turning
over the yarn, which hangs in the dye-liquor; when it reaches the
opposite end of the vat, the rod full of yarn is lifted out, carried
upwards and then towards the other end of the vat when it is again
dropped into the dye-vat to go through the same cycle of movements
which is continued until the yarn is properly dyed.
#Piece Dyeing Machines.#--Wherever it is possible it is far more
preferable to dye textile fabrics in the form of woven pieces rather
than in the yarn from which they are woven. During the process of
weaving it is quite impossible to avoid the material getting dirty and
somewhat greasy, and the operations of scouring necessary to remove
this dirt and grease has an impairing action on the colour if dyed
yarns have been used in weaving it. This is avoided when the pieces
are woven first and dyed afterwards, and this can always be done when
the cloths are dyed in one colour only. Of course when the goods are
fancy goods containing several colours they have to be woven from dyed
yarns.
The most common form of machine in which pieces are dyed is the
jigger, commonly called the jig, this is shown in figure 16. It
consists of a dye-vessel made long, sufficiently so to take the piece
full width, wide at the top, narrow at the bottom. At the top on each
side is placed a large winding roller on which the cloth is wound. At
the bottom of the jig is placed a guide roller round which passes the
cloth. In some makes of jigs there are two guide rollers at the bottom
and one at the top as shown in the illustration, so that the cloth
passes several times through the dye-liquor. In working the cloth is
first wound on one of the rollers then threaded through the guide (p. 051)
rollers and attached to the other winding roller. When this is done
dye-liquor is run into the jig, and the gearing set in motion, and the
cloth wound from the full on to the empty roller. With the object of
keeping the piece tight a heavy press roller is arranged to bear on
the cloth on the full roller. When all the cloth has passed from one
roller to the other it is said to have been given "one end". The
direction of motion is now changed and the cloth sent in the opposite
direction through the jig and the piece has now received another
"end". This alternation from one roller to the other is continued as
long as is deemed necessary, much depending on the depth of colour
which is being dyed, some pale shades may only take two or three ends,
deeper shades may take more. When dyeing wool with acid colours which
are all absorbed from the dye-liquor, or the bath is exhausted, it is
a good plan to run the pieces several ends so as to ensure thorough
fixation of the dye on the cloth.
[Illustration: Fig. 16.--Dye-jiggers.]
It is not advisable in working these jigs to add the whole of the dye
to the liquor at the commencement, but only a part of it, then when
one end is given another portion of the dye may be added, such (p. 052)
portions being always in the form of solution. Adding dyes in powder
form inevitably leads to the production of colour specks on the
finished goods. The reason for thus adding the dye-stuff in portions
is that with some dyes the affinity for the fibre is so great that if
all were added at once it would be absorbed before the cloth had been
given one end, and, further, the cloth would be very deep at the front
end while it would shade off to no colour at the other end. By adding
the dye in portions this difficulty is overcome and more level shades
are obtained, but it is met with in all cases of jigger dyeing. It is
most common in dyeing wool with basic dyes like Magenta, Auramine, (p. 053)
Methyl Violet or Brilliant Green, and with acid dyes like Acid Green,
Formyl Violets, Azo Scarlet or Acid Yellow.
[Illustration: Fig. 17.--Dye-jigger in Section.]
Some attempts have been made to make jiggers automatic in their
reversing action, but they have not been successful owing to the
greatly varying conditions of length of pieces, their thickness, etc.,
which have to be dyed, and it is next to impossible to make all
allowances for such varying conditions.
[Illustration: Fig. 18.--Wince Dye Beck.]
In figure 17 is shown the jig in section, when the working of the
machine can be more easily traced.
#The Jig Wince or Wince Dye Beck.#--This dyeing machine is very largely
used, particularly in the dyeing of woollen cloths. It is made by many
makers, and varies somewhat in form accordingly. Figures 18 to 21 show
three forms by different makers. In any make the jig wince or wince
dye beck consists of a large rectangular, or in some cases (p. 054)
semi-cylindrical, dye-vat. Probably the best shape would be to have a
vat with one straight side at the front, and one curved side at the
back.
[Illustration: Fig. 19.--Wince Dye Beck.]
In some a small guide roller is fitted at the bottom, under which the
pieces to be dyed pass. Steam pipes are provided for heating the
dye-liquors. The beck should be fitted with a false bottom, made of
wood, perforated with holes, or of wooden lattice work, and under
which the steam pipes are placed. The object being to prevent the
pieces from coming in contact with the steam pipes, and so (p. 055)
preventing the production of stains. Above the dye-vat and towards the
back is the wince, a revolving skeleton wheel, which draws the pieces
out of the dye-vat at the front, and delivers them into it again at
the back. The construction of this wince is well shown in the
drawings. The wince will take the pieces full breadth, but often they
are somewhat folded, and so several pieces, four, five or six, can be
dealt with at one time. In this case a guide rail is provided in the
front part of the machine. In this rail are pegs which serve to keep
the pieces of cloth separate, and so prevent entanglements. The pieces
are stitched end to end so as to form an endless band. When running
through the vat they fall down in folds at the back part of the beck,
and are drawn out from the bottom and up in the front. Each part thus
remains for some time in the dye-liquor, during which it necessarily
takes up the dye.
[Illustration: Fig. 20.--Plush Fabric Dyeing Machine.]
Figures 18 and 19 show forms of these wince dyeing machines,
constructed of wood, and very largely used in the dyeing of woollen
cloths. They are serviceable forms, and give very good results, being
suitable for all dyes.
Figure 20 is a form of machine better adapted than the preceding (p. 056)
for the dyeing of plush fabrics. In this kind of cloth it is important
that the pile should not be interfered with in any way, and experience
has shown that the winces of the form shown in figures 18 and 19 are
rather apt to spoil the pile; further, of course, plush fabrics are
dyed full breadth or open. In the wince now shown all troubles are (p. 057)
avoided, and plush fabrics can be satisfactorily dyed in them.
[Illustration: Fig. 21.--Copper Cased Dye Beck. Mather & Platt.]
Figure 21 shows a dye-bath built of iron, cased with copper, suitable
for dyeing most colours on woollen cloths.
[Illustration: Fig. 22.--Read Holliday's Hawking Machine.]
In the jig and wince dyeing machines the pieces necessarily are for a
part of the time, longer in the case of the jigger than in that of the
wince, out of the dye-liquor and exposed to the air. In the case of
some dyes, indigo especially, this is not desirable, and yet it is
advisable to run the cloth open for some time in the liquor so as to
get thoroughly impregnated with the dye-liquor.
The so-called hawking machine, figure 22, is an illustration of Read
Holliday's hawking machine, made by Messrs. Read Holliday & Sons, of
Huddersfield. There is the dye-vat as usual; in this is suspended the
drawing mechanism, whose construction is well shown in the drawing.
This is a pair of rollers driven by suitable gearing, between which
the cloth passes, and by which it is drawn through the machine. A
small roller ensures the cloth properly leaving the large rollers, (p. 058)
then there is a lattice-work arrangement over the pieces are drawn. In
actual work the whole of this arrangement is below the surface of the
dye-liquor in the vat. The piece to be dyed is threaded through the
machine the ends stitched together, then the arrangement is lowered
into the dye-vat and set in motion, whereby the cloth is drawn
continuously in the open form through the dye-liquor, this being done
as long as experience shows to be necessary. This hawking machine will
be found useful in dyeing indigo on wool, in mordanting and dyeing
wool with the Alizarine series of dyes.
CHAPTER IV. (p. 059)
THE PRINCIPLES AND PRACTICE OF WOOL DYEING.
The various methods which are used in dyeing wool have, of course,
underlying them certain principles on which they are based, and on the
observance of which much of the success of the process depends.
Sometimes these principles are overlooked by dyers, with the result
that they do not get good results from their work. It must be obvious
to any person with any technical knowledge that all processes of
dyeing either wool or silk, or cotton or any other fibre, must take
into consideration the properties of the fibre on the one hand, and
that of the dye-stuff on the other. Wool must be treated differently
from cotton, a process of dyeing which gives good results with the
latter fibre would lead to nothing but disastrous effects with wool or
silk; on the other hand, processes are used in the dyeing of wool
which could not be possibly used for cotton on account of the very
different properties of the fibre.
A few words as to the properties of wool as far as they relate to the
methods of dyeing may be of use. Wool has the property of resisting
the action of acids in a great degree, so that it may be treated with
even strong acids with impunity. On the other hand, alkalies and
alkaline solutions have strong action on it; the caustic alkalies
rapidly dissolve wool, and their use must be avoided in all cases of
dyeing this fibre. The carbonates of the alkalies have not so strong
an action, and therefore may be used in moderation; nevertheless, (p. 060)
too strong solutions of these should not be used. Soap has no
disintegrating action on wool, and soap solutions may be used whenever
necessary for cleansing or dyeing wool. Ammonia has no action on wool,
and it may be used in place of soap if desired. There is one feature
of wool that must be alluded to here, and that is its felting
property. When wool is boiled with water and is handled a good deal,
the fibres clot or felt together into a firm coherent mass. This
should be avoided as much as possible, and when wool is cleansed and
dyed in the loose condition it is absolutely necessary that every care
be taken to avoid felting. This condition is much influenced by the
temperature and the condition of the bath in which the wool is being
treated, too high a temperature or too prolonged a treatment tends to
increase the felting, therefore in dyeing wool prolonged treatment at
the boil must be avoided.
Further, the condition of the bath has some influence on this point;
it is found that an alkaline bath tends to considerably increase the
felting properties of the wool, and on this account dyers invariably
avoid the use of both the caustic and carbonated alkalies. Strong soap
liquors have also some influence in the direction of increasing the
felting, therefore soap should not be used if it can possibly be done
without. Ammonia has not so strong a felting action as the other
alkalies. Acids, on the other hand, exert a retarding action on the
felting of the wool, and this is a matter of some interest and
importance in the dyeing of wool, as an acid condition of the bath is
necessary for dyeing by far the great majority of colouring matters on
this fibre. Alkaline salts, such as Glauber's salt and common salt,
exert little or no influence on this felting property, and can be
added to dye-baths with impunity, and in many cases with good effect,
so far as the quality of dyeing is concerned.
So far as the properties of the wool are concerned, it is seen (p. 061)
that an acid condition of the dye-bath will work better than an
alkaline condition, and wherever it is possible to use acids such
should be added.
What has been said in regard to wool is equally true of all fibres
derived from animals in the same way as wool is, such as horse-hair,
fur of rabbits, hares and other animals, although, of course, there
are some minor differences between different furs in their resistance
to the action of acids and alkalies.
The next feature that influences the methods of dyeing wool is the
varying properties of the dye-stuffs, or colouring matters. It is
obvious that those which, like Magenta or Saffranine, have a strong
affinity for the wool fibre must be dyed differently from those which,
like Alizarine and Gambine, have no direct affinity for the wool
fibre, and, further, which require the aid of mordants before they can
be dyed, and on the character of which mordants the colour that is
fixed on the fibre depends.
The dye-stuffs, independently of the question whether they be derived
from natural sources or be of artificial origin, may be roughly
divided into five groups, some of which may also be subdivided again
as will be shown later on. These groups may be named the (1) Neutral,
(2) Basic, (3) Acid, (4) Mordant, and (5) Indigo dye-stuffs. The first
two classes are practically dyed in the same way; but as there is a
great difference in the chemical composition of the colouring matters
comprised in them, it will be best to consider them separately.
_First Method_.--This method is used in applying the now large and
increasing group of azo dye-stuffs, which are characterised by being
able to dye unmordanted cotton from a simple boiling bath. The
dye-stuffs that are applied by the method now to be described include
such as Benzopurpurine, Chrysamine, Chrysophenine, Titan red, Titan
yellow, Benzo brown, Diamine red, Diamine brown, Diamine blue, (p. 062)
Congo blue, Congo red, etc. The dyeing is done in a bath at the boil.
If the bath contained only the dye-stuffs there would be a liability
for the dyeing to be uneven, to prevent which a saline compound, such
as salt, is added. Taking it all round, salt is the best body to add
as it suits all colours very well indeed. Then come Glauber's salts;
borax and phosphate of soda can also be used, but, owing to their
slight alkaline properties, they are not so good as the neutral salts,
like the two first named. When these colouring matters are dyed on
cotton some of them dye best in a bath containing potash or soda, but
these bodies, for reasons previously pointed out, are not available in
wool dyeing, and should never be used. Wool dyes best in a slightly
acid bath, and this may be taken advantage of in dyeing the yellows
and blues of this group by adding a small quantity of acetic acid. The
reds, as a rule, are affected by acids, and, therefore, it is not
possible to use an acid bath with Benzopurpurine, Congo red, with the
possible exception of the Titan reds and scarlets, Diamine scarlet,
Benzo fast scarlet, Purpuramine, which are faster to acetic acid than
the other reds of this class of dye-stuffs.
Probably the best plan of dyeing these colours is to first heat the
bath to about 160° F., then enter the goods, and turn over two or
three times to ensure that they are thoroughly impregnated with
dye-liquor. The bath is now raised to the boil, and, steam being
turned off, the goods are handled without further steam until the
desired shade is obtained. Another plan is to enter the goods when the
bath is at about 150° F., and, after raising to the boil, to work for
half to one hour at that heat; but the plan first described gives
rather better results, and is far preferable. The dye-baths, as a
rule, are not completely exhausted, except when very pale shades are
being dyed; in no case is it necessary to throw the dye-bath away, but
simply to add the required amount of dye-stuff for a new batch; (p. 063)
with those colouring matters which are not entirely exhausted from the
bath a smaller amount, generally about three-fourths only, is required
to be added, with about one-third the quantity of salt which was added
to the first bath. Of course it is not advisable to keep the same bath
or liquor in work always, but after about twenty or thirty batches of
goods are dyed to throw it away and start a fresh liquor.
As a rule it will be found that these dye-stuffs are more thoroughly
taken up from the bath than is the case in dyeing cotton; thus often
with the same amount of dye-stuff in proportion to the material used
the wool will dye rather a deeper shade than will cotton. In some
cases, especially with the blues and violets, the shade is greatly
different on wool from what it is on cotton, being generally redder
and much stronger. (See the chapter on Union Dyeing.) While the shades
are somewhat faster to light on wool than they are on cotton, they are
no faster to soaping and in some cases not so fast. What may be the
function of the salt, or other such added substance, is not very
clear, probably it plays the same part as to similar bodies in dyeing
the basic dye-stuffs. The dye-stuffs which are referred to above are
all derived from coal-tar, and in the recipes which follow many
examples of their use will be found.
There are but few natural dye-stuffs that have any direct affinity for
wool. Turmeric, saffron, anotta, are about the only representatives,
and these are not of much importance in wool dyeing by themselves,
although they are sometimes used in conjunction with other natural
dye-stuffs, when they are applied by a process which is adapted more
especially for the other dye-stuff which is used.
_Second Method_.--The method of wool dyeing now being dealt with does
not differ essentially from that described above, but as it is applied
to quite a different class of dye-stuffs it is thought better to
consider it as a second method. The dye-stuffs made use of in (p. 064)
this method are what are called the basic coal-tar colours, and it may
be remarked in passing that there are no natural colouring matters
having the same properties. These dye-stuffs are derived from a number
of so-called colour bases, such as Rosaniline, Pararosaniline,
Methylrosaniline, Phenyl-rosaniline, and Auramine base. Many of these
are colourless bodies containing the Amidogen group NH_{2}, which
imparts to them basic properties enabling them to combine with solids
to form salts, and these salts have a strong colouring power. They
form the commercial dye-stuffs Magenta, Saffranine, Thioflavine T,
Auramine, Benzoflavine, Brilliant green, Methyl violet, etc., and
these are salts (usually the hydrochloride) of colour bases. All these
basic dye-stuffs have strong affinity for the wool fibre, and will
immediately combine with it, dyeing it in colours which resist
washing, etc., to a considerable extent, although there are great
differences between the various members of the group in this respect.
It has been shown that what takes place in dying wool with these
colouring matters is that the colour base combines with the fibre the
acid of the dye-stuff remaining in the dye-liquor.
Although it is possible to dye wool with the basic dyes from a plain
bath containing water only, yet the results are not satisfactory,
especially when working on a large scale; and for dyeing pale shades
especially, the affinity of the dye-stuff for the fibre is so great
that the first portions of the goods which are entered into the
dye-bath have a great tendency to absorb all the dye-stuff, or the
larger proportion of it, so that uneven dyeing is the result, one end
of the piece of cloth being darker than the other end. This defect is
particularly accentuated when pale tints are being dyed, the colouring
matter being completely absorbed before all the goods are entered into
the bath, but it may be remedied by adding the dye-stuff to the bath
in small quantities at intervals during the process of dyeing. The (p. 065)
best and most satisfactory method, however, is to add to the bath 10
per cent. of the weight of the wool of Glauber's salt, or some other
neutral alkaline salt, which addition almost entirely prevents any
defect of uneven dyeing. How these assistant mordants act is somewhat
uncertain, the explanation generally given is that they exert a
slightly solvent action on the dye-stuff, and so prevent it from going
upon the fibre too readily. This is scarcely an adequate explanation,
but in want of a better it will have to stand.
The affinity of the basic dyes for wool increases with increase of
temperature. This is a property that has an important bearing on the
method of dyeing, and to any person who pays some attention to theory
in its practical applications it indicates the most rational method of
working, which is to enter the goods into the bath cold, or, at the
most, at a hand heat, then, after working a short time to get the
goods thoroughly impregnated with the dye-stuff, to gradually raise
the temperature to the boil and work for from half an hour to an hour
longer, even if before this time the dye-bath be exhausted. The reason
for giving a fair length of time in the bath is to get the colour
properly fixed on the fibre. The combination of the dye-stuff and the
fibre is a chemical one, and, as stated above, the dye-stuff has to be
decomposed so that the base may combine with the essential constituent
of the wool fibre, while it is obvious that this decomposition and
then the union of the colour base with the wool must take time, and as
it is effected more easily and completely at the boiling point, it is
advisable to work the goods in the bath so as to fully insure that
they are given the necessary time for the chemical change to take
place.
The dye-bath is generally completely exhausted of colour, but if
fairly clean it need not be thrown away, but used for another batch of
wool by simply adding more Glauber's salt and dye-stuff. After a (p. 066)
time the bath gets too dirty to used, when it may be thrown away, and a
new dye-liquor made up.
In dyeing for pale shades it is best to add the dye-stuff in small
quantities at intervals during the process of dyeing, and to run the
goods quickly through the bath, so as not to give the dye-stuff too
much opportunity to become absorbed by a portion of the goods only.
Working according to the hints given above, the dyeing of wool with
the basic coal-tar colours may be carried out in a very satisfactory
manner.
_Third Method_.--This method consists in dyeing the wool in a bath
containing the dye-stuff, a little acid (usually sulphuric) with the
addition of Glauber's salt, or some other alkaline salt, the essential
feature or principle being that the bath is an acid one. This method
is applicable to the large group of azo dye-stuffs derived from coal
tar, and also to the acid dyes prepared from the basic coal-tar
colours by the process of sulphonation.
It is also used to apply indigo carmine to wool, probably the only
good example of a natural dye-stuff applied by this process. Most of
the natural colouring matters, such as logwood and fustic, belong to
another group of dye-stuffs.
The simple azo dyes are combinations of two or more organic bases,
united together by a peculiar and characteristic group of nitrogen
atoms. Such azo colours are, however, insoluble in water, and
therefore they cannot be used in dyeing and textile colouring,
although the firm of Messrs. Read Holliday & Sons years ago patented a
process whereby these insoluble azo colours could be developed on the
cotton fibre direct, and thus fabrics made from that fibre could be
dyed in fast colours. When these insoluble azo colours are treated
with sulphuric acid they are converted into sulpho acids, undergoing
what is called sulphonation, an operation of the greatest (p. 067)
importance and value in the preparation of dye-stuffs. The preparation
of indigo extract or indigo carmine from indigo is also a case of
sulphonation. The sulpho-acids of the azo colours, of the basic dyes,
and of indigo are usually insoluble in water, although there are great
differences in their properties in this respect. They will combine
with bases such as soda, calcium and potash to form salts which are
soluble in water, and it is usually in the form of sodium salts that
these azo and acid dye-stuffs are sold to the dyer and calico printer.
It is this power of combination with bases that makes them of value in
wool dyeing. As Knecht and other authorities have pointed out, the
wool fibre contains a basic principle capable of combining with acid
bodies, and in wool dyeing with the colouring matters under
discussion, this combination occurs between the sulpho-acid of the
dye-stuff and the basic principle of the wool fibre.
This points to the fact that the dye-stuffs of this class do not
combine with the wool in the form in which they are supplied to the
dyer as sodium salts, which is shown by a property that many if not
all of them possess, of not dyeing the wool fibre in a neutral bath.
If a piece of wool be immersed in a solution of, say, a scarlet or
indigo extract, which is neutral it is not dyed. The dye-liquor may
penetrate thoroughly throughout the fabric, but if the piece of wool
be lifted out, and allowed to drain, nearly all the liquor will drain
away, and leave the wool nearly if not quite white, showing that the
dye-stuff in the form in which it is sold has no affinity for the wool
fibre. If now a few drops of sulphuric acid be added to the dye-liquor
the wool will become dyed. The sulphuric acid liberates the free
sulpho-acid of the dye-stuff, and this is now in a form to combine
with the wool fibre, which it does. This is the fundamental principle
underlying the acid method for dyeing wool with the acid group of
colouring matters.
The practical application of the principle laid down above is a (p. 068)
matter of simplicity compared with the other methods of dyeing. The
composition of the bath is given above. It is best to enter the wool
at from 150° to 160° F. and then to raise the temperature slowly to
the boil. This method of proceeding gives time for the free colour
acid of the dye to be liberated from the dye-stuff on the one hand,
and for its combination with the wool fibre on the other. In dyeing
pale tints with acid dye-stuffs it is a good plan not to add the acid
until after the goods have been entered into the bath and worked for a
short time to enable them to become impregnated with the dye-liquor;
the acid may be then added, and the dyeing may be finished as usual.
By this plan of working more even dyeings can be obtained than by
simply entering the goods direct into an acidified dye-liquor.
Any kind of acid may be employed, but generally sulphuric acid is
used, partly because it is cheap, and partly because it is the
commonest acid known. Acetic acid is also used in many cases.
_Fourth Method_.--We now come to the fourth method of dyeing wool.
Strictly, perhaps, it is not a single method, but a group of methods,
which are used to supply a certain class of dye-stuffs to the wool
fibre; but as the governing principle depends upon the peculiar
property of the dye-stuffs now to be noticed, which underlies all the
variations of the process of dyeing, it has been thought better to
speak of the fourth method rather than to subdivide further, in which
case the fundamental principle might be lost sight of.
The class of dye-stuffs included in the fourth group was named by
Bancroft the "adjective" group, because they require the aid of a
second body, named the mordant, to properly develop and to fix the
colour of the dye-stuff on the wool. It is sometimes known as the
"mordant dye-stuff" class, and this is perhaps its best name. This (p. 069)
group of colouring matters comprises dye-stuffs of both natural and
artificial origin, the latter of which are getting very numerous and
valuable, and bid fair to displace the natural members of the group.
With but few exceptions the adjective dye-stuffs are not colouring
matters of themselves, _i.e._, they will not dye wool or other fibres
by themselves. Some are coloured bodies, such as fustic, logwood,
Persian berries, Anthracene yellow, etc., but many are not so, and
some possess but little colour, which, moreover, gives no clue to the
colours that can be developed therefrom.
All the colouring matters of this class possess either a distinctively
acid character, or belong to the class of phenols, which, while not
being true acids, still possess weak acid functions that enable them
to combine with bases like acids. These bodies have the property of
combining with bases and metallic oxides, such as soda, potash, iron,
alumina, chrome, tin, nickel, cobalt, etc., forming a series of salts.
Those of soda and potash are usually soluble in water, while those of
the other metals are insoluble, and are usually of strong colour. It
is on this property of forming these insoluble coloured bodies, colour
lakes, as they are called, that the value of the adjective dye-stuffs
in dyeing depends.
The group of adjective colouring matters may be subdivided into two
divisions, not depending upon any differences in the mode of
application, but upon certain differences in the results they give.
Perhaps the best example of an adjective dye-stuff is Alizarine. This
body has a faint red colour, but of itself possesses absolutely no
colouring power. When, however, it is brought into combination with
such metallic oxide as alumina, iron and chrome, then it forms
coloured bodies, the colour of which varies with the metal with which
it is in union, thus with alumina, it is a bright red; with iron, a
dark violet, almost black; with chrome, a deep red; with tin, a (p. 070)
scarlet; and so on. This is a representative of the true adjective
dyes, which comprise most of the so-called Alizarine dye-stuffs, and
logwood, fustic, and most of the natural dye-stuffs. Another division
of the group includes a few colouring matters of recent introduction,
like Azo green, Alizarine yellow, Galloflavine, Anthracene yellow,
Flavazol, etc., which, while forming insoluble colour lakes with
metallic oxides, do not give different colours with different metals.
This class of dye-stuffs, owing to their forming these insoluble
colours, gives really fast colours, capable of resisting lengthened
exposure to light and air, and resisting washing, acids and alkalies.
Of course there are differences between the various members of the
group in this respect, and even the resisting power of an individual
member depends a good deal on the metal with which it is combined, and
the care with which the process of dyeing has been carried out.
In the dyeing of these adjective dye-stuffs, upon the various fibres,
and on wool in any particular, the object is to bring about in any
convenient way the formation on the fibre of the metallic combination
of the colouring principle and the mordant, and it is obvious that if
a satisfactory result is to be obtained, then this must be done in a
very thorough manner. There are three ways in which this combination
of colouring principle and mordant may be brought about in dyeing wool
with these bodies, we may either mordant the wool first, and then
apply the dye-stuff, or we may impregnate the wool with the dye-stuff
first, and then fix or develop the colour afterwards, or, lastly, we
may carry on both operations in one process. Each of these methods
will now be discussed, and their relative advantages pointed out.
The mordanting method is one of the most generally useful. It consists
in first causing a combination of the metal with the wool fibre. (p. 071)
This is carried out by boiling the wool in a solution of the metal,
such as bichromate of potash, chrome alum or chrome fluoride when
chrome is to be used as a mordant, with alum or sulphate of alumina
when alumina is required to be deposited on the fibre, and with
copperas when iron is to be the mordant. It is best to add a little
oxalic acid, cream of tartar, or tartaric acid to the mordanting bath,
which addition helps in the decomposition of the metallic salt by the
wool fibre, and the deposition of the metallic oxide on the wool. With
bichromate of potash, sulphuric acid is often used, much depending
upon the character of the mordant required. Some dye-stuffs, such as
logwood for blacks, work best when the wool is mordanted with chromic
acid, which is effected when sulphuric acid is the assistant mordant.
Other dye-stuffs, such as fustic, Persian berries and Alizarine
yellow, are best dyed on a basic chrome mordant, which is effected
when tartar or oxalic acid is the assistant mordant used, or when some
other form of chrome compound than bichrome is employed.
The actual mordanting is done by boiling the wool in a bath of the
mordant, the quantity of which should be varied according to the
particular mordant that is being employed and to the quantity of
dye-stuffs which is to be used. It is obvious that for a fixing deep
shade of, say, Alizarine on the wool, a larger quantity of mordant
will be required than to fix a pale shade; sometimes this point is
overlooked and the same amount of mordant employed for pale or deep
shades. The best plan of carrying out the mordanting is to enter the
wool in the cold bath or at a hand heat, and then raise to the boil
and continue the boiling for one hour; of course the goods should be
kept turned over during the process to facilitate the even mordanting
of the wool. A great deal of the success of dyeing with the dye-stuffs
now under consideration depends upon the efficiency with which the (p. 072)
mordanting has been carried out. If this is at all unevenly done then
no amount of care in the succeeding dyeing process will lead to the
development of an even dyeing. After the mordanting is finished the
goods should be rinsed with water, but it is not necessary to dry
them.
The next stage in the process is the actual dyeing operations, which
is done by immersing the mordanted wool in a bath of the dye-stuff or
mixture of dye-stuffs.
The fundamental principle is to bring about the combination between
the colouring principle of the dye-stuff and the metallic oxide which
has been deposited on the wool in the previous mordanting process. As
neither of these bodies, however, is very energetic it follows that
the action must be a slow one, and, therefore, time is a highly
important factor in the dyeing of wool by the mordanting process. The
combination between the dye-stuff and the mordant is influenced also
by temperature, and is most active at the boiling point of water. It
is, therefore, needful to conduct this operation at that temperature,
but it would be a wrong way to introduce the mordanted material into a
boiling bath of the dye-stuff; nothing would conduce to uneven dyeing
so much as that course. The best method of working, which, moreover,
is most particularly applicable to the series of Alizarine dye-stuffs,
is to enter the goods in a cold bath of the dye-stuff, and to work
them for a short time to get them thoroughly impregnated, a condition
which is essential if even dyeing is the goal aimed at, then to raise
the temperature of the bath gradually to the boil, the goods being in
the meantime well worked. The dyeing is continued for from one to one
and a half hours at the boil.
It is important in dyeing by this process, especially when using
Alizarine, to keep the temperature of the bath as uniform as possible,
and the goods well worked. Alizarine, and some other members of (p. 073)
this class, are rather sensitive to heat, and if a dye-vat be hot at
the bottom and cold at the top uneven dyeing is sure to be the result;
this is due to the greater affinity of the Alizarine for the mordant
at the high than at the low temperature, and thus more is fixed on to
the wool. The remedy for this is to so construct the heating
arrangements of the vat that the temperature shall be as uniform as
possible, while the goods should be kept continually turned over, and
every portion of them brought into intimate contact with the
dye-liquor. The continuance of the dyeing operations for one and a
half to two hours after the vat has reached the boil is necessary to
properly develop and fix the colour on the fibre; a short boil leaves
the goods of a poor shade, without any solidity about it, and the
colour is loose, while a longer boil brings up a solid shade and a
fast colour.
Although it is not absolutely necessary to add any acid to the
dye-bath during the dyeing operations, yet as the Alizarines and most
of this class of dye-stuffs dye better in a slightly acid bath it is
advisable to add a small quantity of acetic acid, say about one pint
to every 100 lb. of goods; this serves to correct any alkalinity of
the water, which may be due to its containing any lime. Dye-stuffs of
the acid class, such as indigo extract, Cloth red, Acid magenta, etc.,
may be used along with the Alizarine dye-stuffs, in which case the
addition of acid to the dye-bath becomes necessary, but too great an
excess of acid should be avoided, as it interferes somewhat with the
dyeing of the mordant dyes.
This is by far the best and most generally used method of applying
these mordant dyes. It is not a costly process, being indeed economical,
as it only requires just the right amounts of drugs and dye-stuffs,
and there is the minimum loss of material in the mordanting and
dye-baths. Shades can be brought up with the greatest ease, although
it is well in the dyeing to add rather less dye-stuff than is (p. 074)
actually required, and to add more when it is seen how the shade is
coming up. The labour is the most important item in the mordanting and
dyeing method.
The proportions of material used to the weight of the wool are: Of
bichromate of potash, 3 per cent. for full shades, and 1 per cent. for
pale shades; of fluoride of chrome, the same quantities; of acetate of
chrome, according to the strength of the solution used; of alum, 10 to
20 per cent.; of sulphate of alumina, 5 to 10 per cent.; of copperas,
5 to 10 per cent.; of tartar, 1-1/2 to 2-1/2 per cent.; of oxalic
acid, 1 to 1-1/2 per cent.; of sulphuric acid, 1 per cent.; of argol,
2-1/2 to 5 per cent.; of tartaric acid, 1 to 1-1/2 per cent.; but of
course in an article like this it is impossible to give definite
quantities.
_Second Method_. #Stuffing and Saddening.#--This method consists in
first treating the wool with a solution of the dye-stuff, and then
with a solution of the mordant required to develop and fix the colour.
This method is more particularly applicable to such dye-stuffs as
camwood, cutch, logwood, madder, fustic, etc., the colouring
principles of which have some affinity for the wool fibre and will
directly combine with it. It is not suitable for the application of
the Alizarine colours. The saddening may be and is commonly done in
the same bath, that is, after the wool has been stuffed it is lifted,
the mordant--copperas, bluestone, bichrome, or alum--is added, and the
wool is re-entered into the bath. This cannot be considered a good
method of working; the shades obtained are full and deep and fairly
fast, but there is usually a considerable loss of colouring matter, as
the wool in no case abstracts the whole of the dye-stuff from the
bath; what excess is left combines with the mordant when the latter is
added, forming an insoluble colour lake, which falls down to the
bottom of the dye-vat and is wasted, or it may go upon the wool in (p. 075)
a loose, unfixed form, and cause it to rub badly and come off in
milling. Then it is rather difficult to dye to shade, much of the
result depending on conditions over which the dyer has little control.
Working as he does with dye-stuffs of unknown colouring power, which
may vary from time to time with every fresh batch of material, it is
evident that, although the same quantities may be used at all times,
at one time a deeper shade may be obtained than at another, and as it
is impossible to see what is going to be the result, and if by
mischance the shade does not come deep enough it cannot well be
rectified by adding a quantity of dye-wood to the bath, because the
mordant in the latter will prevent the colouring matter from being
properly extracted, and only a part of that which is extracted is
fixed on the wool, the rest being thrown away in the dye-bath, and
partly on the particles of wood themselves, when logwood, camwood,
etc., are used in the form of chips or powder. Dyers being well aware
of this, are in the habit when mistakes occur of bringing up to shade
with soluble dye-stuffs--archil, indigo extract, and such like.
This method, as stated above, is very wasteful, not only of
dye-stuffs, but of mordants. In no case does the wool absorb the whole
of the colouring matter from the bath, the unabsorbed portion goes
down to the bottom of the bath when the mordant is added, so that when
the dyeing is finished, the dye-bath is charged with a large quantity
of colouring matter in an unusable form which has to be thrown away,
thus at once adding to the pollution of the river into which it is
run, and to the cost of the process of dyeing. As attention is being
directed more and more to the question of the prevention of pollution
of rivers, and as the waste liquors from dye-works add to the apparent
pollution to a very considerable extent, dyers will have to develop
other modes of dyeing than that of stuffing and saddening in one bath.
The principle of dyeing by stuffing and saddening may be carried (p. 076)
out by the use of two separate baths; in fact, it is done in the case
of dyeing a cutch brown from cutch and bichromate of potash. The goods
are first treated in a bath of the dye-wood for a short time, then
rinsed, and the colour is developed by padding into a saddening bath
of the mordant. By this method the baths, which are never quite
exhausted, can be retained for future use, only requiring about 1/2 to
3/4 of the original quantities to be added for each succeeding batch
of the goods, in fact, in some cases, as in cutch, old baths work
better than new ones.
The advantage attached to this method of working is that arising from
economy of dye-stuff and mordant, and the reduction of the pollution
of the stream on which the works are situated. The disadvantages are
that the cost of labour is increased by there being two baths instead
of one, and that the shades obtained are not always so full as with
the one-bath method. This, of course, can be remedied by running the
goods through the baths again, which, however, adds to the cost of the
process, but there is this much to be said, the shade can be better
brought up than by the one-bath process. In some cases the methods of
mordanting, dyeing and saddening are combined together in the dyeing
of wool, thus, for instance, a brown can be dyed by first mordanting
with bichrome, then dyeing with camwood and saddening in the same bath
with copperas. The shades obtained are fairly fast and will stand
milling. The disadvantages of this process are the same as those
attached to the dyeing and saddening in one bath.
Now we come to the last method of dyeing wool with mordant and colours,
that in which the operation is carried out in one bath. This can only
be done in those cases where the colour lake that is formed is somewhat
soluble in dye-liquors, which usually have slightly acid properties; or
where the affinity between the two bodies (colouring matter and (p. 077)
mordant) is too great. This method can be carried out in, for instance,
dyeing a cochineal scarlet with tin crystals, a yellow from fustic and
alum, a black from logwood and copperas and bluestone, a red from
madder and bichrome, and the dyeing of the Alizarine colours by the
use of chrome fluoride, etc.
The shades obtained are usually not so deep as those got by the
mordanting and dyeing process, but are frequently nearly so. In some
cases, as in dyeing with fustic or logwood, it gives rather brighter
colours, due to the fact that the tanning matters present in the
dye-stuffs is not fixed on the wool, as is the case with the
mordanting method, but is retained in the dye-bath. For dyeing with
logwood and copperas or bluestone the process is not a good one, as it
does not give as full shades as by the ordinary process. For dyeing
with the Alizarine colours, using chrome fluoride as the mordant, it
can be applied with fair success. There are advantages in the saving
of time and labour and in the amount of steam required, all of which
are important items in dyeing.
It is rather troublesome to match off by this process, but it can be
done. For light shades the process will be found very useful, as these
cost less than by any other process. The dye-baths may be retained for
future use, although in process of time they become too dirty for use,
when they must be thrown away.
#Level Dyeing.#--The first condition for successful dyeing is that the
fibres to be treated are absolutely clean. A careful washing is not
enough for this purpose. Cleanliness is undoubtedly the condition
which the fibre must possess to enable the dye to hold on and not to
come off the fibre, this latter causes a loss of dye-stuff, soils the
whites, and gives rise to trouble between the dyer and finisher; it is
also the condition for making the dye go on the wool evenly. The (p. 078)
washing must be done at the boil, so that the fibre is well wetted
out and all the air bubbles adhering to it are driven out. But this is
not enough; it must be accompanied by a scouring operation, not only
in the case of fibres of which the dyer does not know whether they
have been scoured, but also when they have already been scoured and
bleached. The kind of scouring that the fibres receive in this case
need only be of a comparatively light character, but it must never be
omitted, even for dark shades, as the traces of grease which the fibre
contains are the causes of nearly irremediable stains in the dyeing
operations. Even in dyeing black wool it is of the greatest importance
to have the fibre suitably scoured.
The fatty matters which the fibre contains may belong to the
components of the fibre itself and be natural matters, but in the case
of wool yarns and cloths they are mostly dressing oils, from which the
dyer cannot be too anxious to free the wool before dyeing. Some
practical methods of preparatory treatment of the fibres before dyeing
may therefore be described here with advantage.
Cotton is boiled off at actual boiling heat for two hours, with 8 per
cent. of its weight of carbonate of soda and a little soft soap, which
treatment is sufficient for dark colours.
For light colours it is necessary that the cotton be bleached. Wool is
scoured with soda and soap in the proportion of 10 lb. soda and 2 lb.
Marseilles soap for 100 lb. wool. Silk is scoured by boiling for one
and a half hours in a boiling bath with 30 per cent. of its weight of
soap. For light colours a second boiling should be given, with 15 per
cent.
The careful cleaning of wool previous to dyeing is of exceptional
importance. Raw wool is cleaned with carbonate of soda and ammonia. For
50 lb. wool to be cleaned 6 lb. carbonate of soda and 1-1/2 lb. (p. 079)
ammonia are added to a bath of 150 gallons water. The wool is laid
down in it for twenty minutes at 35° C., taken up, squeezed, treated
for fifteen minutes in another bath, with 5 lb. carbonate of soda and
then rinsed. The first bath must be renewed as often as possible,
because it contains all the impurities. In the case of woollen yarn
30 lb. require two tubs of 40 gallons capacity. The first tub is to
contain 35 gallons water and 2 lb. ammonia at 10° Be. After working
the skeins for three minutes in it they are left to stand for fifteen
minutes, then wrung out, and the operation is repeated in the second
tub. Finally, the yarn is rinsed several times in soft water.
Woollen piece goods are treated in a large wooden tub at 40° C. with
4 lb. carbonate of soda and 2 lb. carbonate of ammonia for 80 lb.
material. The pieces are moved about for twenty minutes, laid down in
the bath overnight, again turned for ten minutes and hydro-extracted.
They may also be handled for forty minutes in a bath of 2 oz. ammonia
for 100 lb. wool at 60° C., and then for twenty minutes in clear water
at 60° C.
After wetting or preparatory treatment, it will be best to proceed
immediately to dyeing; if the fibres be left in a heap for too long a
time, there is danger that they may become heated, or at least that
the moisture may be irregularly distributed by the occurrence of
partial drying, causing an uneven fixation of the colour in the first
stages of dyeing. The first two conditions of successful dyeing are,
therefore, a suitable wetting out and scouring. The dyer, however,
must not be less careful to see that the dye-bath is what it ought to
be.
Whenever possible the dye-stuff must be dissolved separately, or at
least the bath not entered before the dye-stuff is well dissolved.
Artificial dye-stuffs require particular attention to this point,
because the presence of undissolved particles is the cause of (p. 080)
irregularities, such as streaks, or, at least, specks. The solution is
mostly made hot as follows: After pouring water at 180° F. upon the
dye-stuff, stir gently, strain through flannel or through a very fine
sieve, and pour more water upon the residue until nothing more is
dissolved. As is well known, the artificial dye-stuffs often contain
insoluble matter, resins, etc. It is therefore advisable to use only
soft water for this operation.
The solutions of artificial dye-stuffs are ordinarily made at the rate
of 1 to 5 lb. per 10 gallons of water, 2 lb. being the proportion
mostly employed. This depends more or less on the solubility of the
dye-stuff. Old solutions sometimes contain crystals of the dye-stuff
which have separated out. These should be redissolved by heating
before the solution is used. But it is best to make only such a
quantity of solution as will suffice for immediate requirements.
With paste colours care should be taken to keep them in closed vessels
in such a manner that they will not become hard by evaporation, and
they should not be kept in any place where they are likely to freeze
in winter time. In such an event it is not an uncommon circumstance
for the casks or other vessels containing them to burst, with a
consequent loss of dye-stuff. Before any of the paste is withdrawn
from the cask, it is advisable to stir well up with a wooden stirrer.
In adding dye-stuff during the actual dyeing operation, it is
advisable to add the dye-stuff to the bath in two or three portions,
always taking out the goods before adding each lot of dye-stuff, and
stirring up the contents of the bath before re-entering the goods.
Another important condition of obtaining a level dyeing is to proceed
slowly, beginning with a weak bath at a moderate temperature, and
rising gradually to a boil. If necessary to retard the dyeing from the
commencement, then an assistant mordant is added to the dye-bath, in
the shape of soda crystals or phosphate of soda for the benzidine (p. 081)
colours on cotton; bisulphate of soda or Glauber's salt in dyeing with
azo colours or acid colours on wool; or tartar may be used in most
cases with good effect, causing the wool to have a softer feel. Finally,
the evenness of the dyeing is much increased by the frequent turning
over of the material in the dye-bath, so managing this in the case of
wool as to avoid felting.
When dyeing with a mordant, the dyer should see that the mordanting
operation is thoroughly well done, for as much care is required for
the mordanting as for the actual dyeing; in fact, if anything, the
mordanting should be done with rather more care, as if it be at all
defective no amount of care in the following dyeing operations will
ensure a level dyeing. Chrome mordanted wool should be dyed without
delay, as it is rather sensitive to light, especially the yellow sort,
which gradually changes into the green sort of chromed wool.
One peculiarity of dyed wool is that it will continue to take up
colour after it is removed from the dye-bath, especially if it
contains any of the hot dye-liquor, therefore it is very desirable to
wash the wool as soon as possible after its removal from the dye-bath.
It is best, however, not to take the wool out of the hot bath, but to
leave it in until the bath becomes cool, and then to take it out, by
this means the colour becomes deeper and more solid looking, and is
faster on the wool.
One cause of irregular dyeing may be mentioned, as it is occasionally
met with, namely, the presence of foreign fibres in the goods, cotton
in wool fabrics, and even of different varieties of the same fibre.
All dyers know that dead or immature cotton will not dye up properly,
a fact or defect more especially met with in indigo dyeing than probably
in any other colour. Then wools from different breeds of sheep vary
considerably in their dyeing power. Fine wools take up more colour (p. 082)
than coarse, and, consequently, even from the same bath, will come out a
deeper shade; if a fabric, therefore, contains the two kinds of cotton,
or the two kinds of wool, they will not dye up evenly.
In the preceding sections brief notes have been given about the
principal methods of dyeing wool, with some indications of the dyes
which can be used under each method. In the succeeding sections will
be given a number of recipes showing how, and with what dye-stuffs,
various colours, shades and tints can be dyed upon wool. It will be
understood that these recipes are applicable to all kinds of woollen
fabrics, loose wool, slubbing, yarns in any form, woven worsted or
woollen cloths, felts of any kind, etc., all these different forms
require handling in a different way; it would not do, for instance, to
treat a quantity of slubbing in the same way as a piece of worsted
cloth, while hanks of yarn require a different mode of handling to a
quantity of hat bodies. The different kinds of woollen fabrics require
to be dealt with in different kinds of machines, and this has already
been dealt with in the chapter on Dyeing Machinery and Dyeing
Manipulations.
To describe and illustrate the application of all the various woollen
dye-stuffs, whether of natural or artificial origin, and to show the
great variety of shades, etc., which can be obtained with them, either
all one or in combination, would require not one, but many volumes of
the size that this present work is intended to be. Therefore, it
becomes necessary to make a selection from the best-known and most
used of the various dyes, and illustrate their application by a number
of recipes, all of which, unless otherwise stated, are intended to be
for 100 lb. weight of woollen material of any kind. It may also be
pointed out that, as a rule, the recipes may be applied to the dyeing
of fabrics made with other animal fibres than the wool of the sheep,
as, for alpaca, cashmere, camel-hair, hare or rabbit fur, etc., (p. 083)
inasmuch, as, with the exception of silk, all animal fibres practically
possess the same dyeing properties.
It will be convenient to point out here that a very large proportion
of the shades dyed on wool and other fabrics are obtained, not by the
use of a single dye-stuff, although this should always be done,
whenever possible, but by the combination of two or more dye-stuffs
together in various proportions. It is truly astonishing what a great
range of shades can thus be dyed by using two or three dyes suitably
mixed together, and one of the things which go to making a successful
dyer and colourist is the grasping of this fact by careful
observation, and working accordingly. Dyers will find much assistance
in acquiring a knowledge of colour and colour mixing from the two
little books on _Colour_, by Mr. George H. Hurst, and the _Science of
Colour Mixing_, by Mr. David Paterson, both issued by Messrs. Scott,
Greenwood & Co., the publishers of the present work.
#Black on Wool.#--Until within a comparatively recent time black was
dyed on wool solely by the use of logwood, combined with a few other
natural dye-stuffs, such as fustic, indigo, etc., but of late the
researches of colour chemists have resulted in the production of a
large number of black dyes obtained from various coal-tar products.
These have come largely into use, but still, so far they have not been
able to entirely displace logwood, chiefly on the score of greater
cost, the use of the natural dye still remaining the cheapest way of
producing a black on wool; although the blacks yielded by some of the
coal-tar black dyes are superior to it in point of intensity of colour
and fastness to scouring, acids and light, as well as being easier to
dye.
Blacks may be obtained from logwood by several methods, either by
previous mordanting of the wool or by the stuffing and saddening
methods, or by the one-bath process. The following recipes will (p. 084)
show how these various methods are carried out in practice:--
_Chrome Logwood Black_.--The wool is first mordanted by boiling for
one and a half hours with 3 lb. bichromate of potash and 1 lb. of
sulphuric acid, working well the whole of the time. It is not
advisable to exceed the amounts of either the bichromate or the acid
here given, these quantities will result in a full bloomy black being
obtained, but any excess gives rise to greyish dull blacks, which are
undesirable. After mordanting rinse well with water, when the goods
will be quite ready for the dye-bath.
The dyeing is done in a bath made from a decoction of 40 lb. of good
logwood. It is perhaps preferable to start cold or only lukewarm,
raise to the boil and work for one hour, then lift, rinse well, and
pass into a boiling bath made from 1 lb. of bichromate of potash and
1/4 lb. of sulphuric acid for half an hour. This extra chrome bath
fixes any colouring matter which may have been absorbed by the wool
but not properly fixed by the mordant already on, it leads to fuller
shades which are faster to rubbing and milling.
The mordanting bath may be kept standing and used again for fresh lots
of wool, in which case it is only necessary to add 2-1/2 lb. of
bichromate of potash and 1 lb. sulphuric acid to the bath for each
additional lot of wool that is being dealt with. Old mordant baths
work rather better than new ones, but the use cannot be prolonged
indefinitely, there comes a time when the bath gets too dirty to use
and then it must be thrown away.
During the operation the bichromate of potash becomes more or less
decomposed and there is formed on the wool fibre a deposit of chromic
acid and chromic oxide, this deposit forms the mordant that in the
subsequent dye-bath combines with and fixes the colouring matter, the
hæmatoxylin of the logwood, and develops the black on the wool.
In place of sulphuric acid, hydrochloric acid can be used with (p. 085)
some advantage as regards the proportion of bichromate decomposed, and
therefore an increase in the amount of chromium oxide deposited on the
wool.
This gives a deep blue black, somewhat wanting in bloom. The following
recipe gives a much bloomier black, but is rather more expensive to
dye.
_Chrome Logwood Black_.--Mordant by boiling in a bath containing 3 lb.
bichromate of potash and 7 lb. tartar. Dye and otherwise treat as in
the last recipe; 4 lb. of tartaric acid used in place of the tartar,
gives rather brighter and bloomier shades. The use of so-called tartar
substitutes is not to be recommended, they give no better results than
does sulphuric acid and are much dearer to use.
A somewhat greener shade of black than is yielded by either of the
above two recipes is the following:--
_Chrome Logwood Black_.--Mordant the wool in a bath containing 4 lb.
oxalic acid and 3 lb. bichromate of potash, afterwards dyeing as in
the first recipe.
All the above recipes give blacks of a bluish tone, which on the whole
have a good bloomy and solid appearance. Often what is called a jet
black is wanted, this can be obtained by following the recipe given
below.
_Chrome Logwood Jet Black_.--Mordant the wool by any of the methods
given above. The dyeing is done in a bath made from 40 lb. logwood and
5 lb. fustic, working as described in the first recipe. Using these
properties a good jet black is obtained, which is quite satisfactory
on the score of solidity and fastness. It is not advisable to exceed
the quantity of fustic here given, or otherwise the black will have a
tendency to assume a greenish tone that is not at all desirable. This
greening becomes more marked when from 7-1/2 to 10 lb. of fustic is
used, or if alum be added to the mordant along with the bichromate of
potash.
Chrome blacks are the best blacks which can be obtained from (p. 086)
logwood. They have, however, a tendency to turn green on exposure to
the weather, which tendency seems to be most prevalent in those blacks
in which sulphuric acid has been used as the acid constituent of the
mordanting bath. The greening may be reduced to a minimum by adding to
the dye-bath about 1 to 2 lb. of Alizarine. Another plan which has
been followed is to give the wool a bottom with 5 to 6 lb. of camwood
or peachwood, then mordanting and dyeing us usual.
_Logwood Black on Wool_.--Boil first for one hour with a decoction of
8 lb. camwood, then lay down for fifty minutes in a boiling bath of
3 lb. bichromate of potash, 1 lb. alum, 1 lb. tartar. It is a good
plan to allow the goods to hang overnight.
The dye-bath is prepared with 45 lb. logwood, 8 lb. fustic, 4 lb.
sumac. Dye one hour at the boil, wash and dry.
_Indigo Black_.--This is sometimes called woaded black, and has an
excellent reputation as a fast black. It is dyed by first giving the
wool a medium blue bottom in the indigo vat by the method of vat
dyeing, which will be described later on, and then dyeing by either
the second or third recipe given above. The use of sulphuric acid is
rather to be avoided in dyeing an indigo vat with chrome and logwood,
as the chromic acid set free during the process is likely to attack
and by destroying the indigo to materially reduce the intensity of the
blue bottom. Or, after blueing in the vat, the black may be dyed or
topped on by the process with copperas, which will be described below.
_Iron Logwood Black_.--Mordant the wool by boiling one and a half to
two hours in a bath made with 5 lb. copperas, 2 lb. bluestone, 2 lb.
alum, and 10 lb. argol. The dyeing is done in a bath of 50 lb.
logwood.
It is not advisable to use more argol than is here given, for (p. 087)
although a little excess will not materially affect the beauty or
brilliancy of the resulting shade, yet such excess is wasteful, and
makes the dyeing cost more than it otherwise would. On the other hand,
too little will cause the shade to become greyish in tone and wanting
in solidity. The copper sulphate (bluestone) added increases the
fastness of the finished black to light, the best proportions to add
are from 2 lb. to 4 lb. for 100 lb. of wool. The shade obtained in the
above recipe is of a bluish-violet hue, if a jet black be wanted, add
5 lb. of fustic to the dye-bath. Another and very common method of
working is the "stuffing and saddening" process, given in the next
recipe.
_Iron Logwood Black_.--Make a bath of 50 lb. logwood, 6 lb. fustic,
and 1 lb. sumac. Work the wool in this for one hour at the boil, lift,
allow the bath to become cool, then add 6 lb. of copperas (ferrous
sulphate) and 2 lb. bluestone; re-enter the wool, raise the
temperature to the boil, and work half an hour, then lift, wash and
dry. On the whole the first method is the most economical and yields
the best blacks, fastest to rubbing.
The iron-copper-logwood blacks are not so fast to acids as the
chrome-logwood blacks, but they are rather faster to light and air,
and equally so to scouring and milling.
One-bath methods of dyeing blacks are sometimes preferred by wool
dyers. Of these the following is an example.
_Logwood Black_.--Make a dye-bath with 50 lb. logwood, 5 lb. fustic,
6 lb. copperas, 2 lb. copper sulphate, and 4 lb. oxalic acid. Enter
the goods and work at the boil to shade. The oxalic acid is added for
the purpose of retaining the logwood-iron-copper black lake, which is
formed on mixing the various ingredients together in solution. On
boiling the wool in the liquor the fibre gradually extracts out the
dye matter and becomes dyed. The use of some of the so-called (p. 088)
"direct blacks" (_noir reduit_, Bonsor's black) is based on the same
principle.
These dyes are mixtures of logwood, fustic or other dye-stuff with
copperas, bluestone and oxalic acid, and only require adding to water
to make the dye-bath. This method of working enables logwood to be
used in conjunction with dihydroxynaphthalene and some other coal-tar
derivatives to obtain blacks of good solidity and much faster to
light, air, acids and scouring than the ordinary logwood blacks.
Another recipe for a one-bath logwood black, using the extracts in
place of the dye-wood itself, is the following:--
_Logwood Black_.--Prepare a dye-bath with 12 lb. logwood extract,
2 lb. fustic extract, 6 lb. copperas, 4 lb. bluestone, 3 lb. oxalic
acid, 2 lb. tartar. Boil the goods in this for one hour.
Some dyers use the dye-woods and prepare from them a decoction by
boiling in water; in some respects this is the most economical plan,
only the dyer has to get rid of the spent dye-wood from which the
colouring matter has been extracted, and this is not always an easy
matter. Some dyeing machines (Smithson's) have been devised which
contain as one of their features a dye-wood extractor, in which the
extraction of the colouring matter of the wood proceeds at the same
time as the dyeing. Good results are got with such machines, although
they leave something to be desired.
Many dyers use the dye-wood extracts which are now made on a large
scale. These are for the dyer much more convenient to use, although
naturally rather more costly. They are approximately five times the
strength of the dye-wood, but they vary very greatly in this respect.
Logwood blacks can be readily distinguished from nearly all other
blacks, in that by treatment with moderately strong hydrochloric acid
they turn a bright red.
No other natural dye-stuff is used in the dyeing of black than these
here given.
Of late years many black dyes derived from coal tar have been (p. 089)
placed on the market. Among these may be enumerated the Acid Blacks of
Messrs. Bead Holliday & Sons; the Naphthol and Naphthylamine Blacks of
Leopold Cassella & Co.; the Victoria Blacks of the Farbenfabriken
vorm, Fr. Bayer & Co.; the Wool Blacks of the Actiengesellschaft für
Anilin Fabrikation; the Azo Blacks of the Farbwerke vorm, Meister,
Lucius & Bruning; and one or two other blacks. These blacks are dyed
very simply, as will be seen from the recipes given below, showing
their application in the production of blacks of a great variety of
tone. None of them dye a true jet black, but generally a bluish black
or a violet black, but the tone may be readily changed to a jet or
dead black by the addition of a little orange, yellow or green
dye-stuff.
They give blacks of a very solid appearance and very bright in tone,
and have the advantage over the logwood blacks of leaving the wool
more supple and less liable to be felted. Moreover, as a rule they are
faster to acids, alkalies and milling than are the logwood blacks, and
as regards fastness to light they excel that dye-stuff. Unfortunately
they are more costly to use, which tells against their entirely
displacing logwood in dyeing blacks on wool.
Still, year by year their use is increasing, and as their price
becomes less their employment will yet further extend. They may be
combined with logwood, as they will dye with equal facility on
mordanted and unmordanted wool.
_Violet Black on Wool_.--Make the dye-bath with 4 lb. Acid Black B, or
Acid Black B B, 3 lb. sulphuric acid, and 10 lb. Glauber's salt. Work
at the boil for one hour. The B brand of these blacks gives shades
slightly redder in tone than the B B. The blacks are quite fast to
light and acids, but not to soaping.
_Blue Black on Wool_.--Dye as in the last recipe, but use Acid (p. 090)
Black S. This dye-stuff produces bluer shades of black than either B or
B B, and they are faster to soaping.
_Jet Black on Wool_.--Make the dye-bath with 4-1/2 lb. Acid Black S,
1/2 lb. Fast Yellow F Y, 3 lb. sulphuric acid, and 10 lb. Glauber's
salt. This shows how, by the addition of a little yellow dye-stuff,
the blue shade may be changed to a full jet black.
_Blue Black on Wool_.--The dye-bath is made with 4-1/2 lb. Naphthol
Black B (or 6 lb. Naphthol Black 3 B), 4 lb. sulphuric acid, and
10 lb. Glauber's salt. Work at the boil for one hour, then lift, wash
and dry. The Naphthol Blacks have long been used in wool dyeing, and
give excellent results, the 3 B brand dyeing much bluer shades than
the B brand. There is also a 4 R brand giving violet blacks. These
blacks are quite fast to acids and alkalies, are fast to light, and
resist washing very well, the B brand being the fastest. The following
recipe shows how a full jet shade can be obtained for these blacks:--
_Jet Black on Wool_.--Prepare the dye-bath with 4-1/2 lb, Naphthol
Black B, 1 lb. Naphthol Green B, 1/4 lb. Indian Yellow, 4 lb.
sulphuric acid, and 10 lb. Glauber's salt.
_Blue Black on Wool_.--Make the dye-bath with 5 lb. Anthracite Black
B, 10 lb. Glauber's salt, and 5 lb. bisulphate of soda, working at the
boil for one hour. Anthracite Black does not require a bath so acid as
do some other coal-tar blacks. The shade obtained is a full blue
black, which is fast to acids; alkalies turn it a little bluer, and
soaping causes some loss of colour.
_Violet Black on Wool_.--Make the dye-bath with 5 lb. Anthracite
Black R, and 10 lb. bisulphate of soda. The black thus obtained is a
good one, fairly fast to acids, alkalies and soaping.
_Dead Black on Wool_.--Make the dye-bath with 6 lb. Anthracite Black R,
1 lb. Anthracene Yellow C, and 10 lb. bisulphate of soda. Work at (p. 091)
the boil for one hour, then lift, add 3 lb. fluoride of chrome and work
again at the boil for twenty minutes. This black is a very fine one, and
is very fast.
_Violet Black on Wool_.--Make the dye-bath with 4 lb. Naphthylamine
Black D, 10 lb. Glauber's salt, and 5 lb. acetic acid. This black is
pretty fast to acids, alkalies and light, but is somewhat loose to
soaping, and, therefore, cannot be used for black goods that have to
be strongly milled. Naphthylamine Black 4 B dyes somewhat bluer shades
than the B brand.
_Blue Black on Wool_.--Prepare the dye-bath with 6 lb. Victoria Blue
Black, 20 lb. Glauber's salt, and 1-1/2 lb. acetic acid, working at
the boil for one hour. A fine blue black, is obtained which is quite
fast to acids, washing and light.
_Greenish Black on Wool_.--The dye-bath is made with 3 lb. Victoria
Black Blue, 2 lb. Fast Yellow F Y, 20 lb. Glauber's, salt, and
1/1-2 lb. acetic acid. The dyeing is done at the boil and takes about
an hour. This shade has a good full tone, and is fast.
_Jet Black on Wool_.--Make the dye-bath with 4 lb. Victoria Black B,
1/2 lb. Fast Yellow F Y, 10 lb. Glauber's salt, and 2 lb. sulphuric
acid, working at the boil for one hour. A very fine shade is thus
obtained, which is fast to acids, alkalies and soaping. By omitting
the Fast Yellow a blue black is obtained, while by using Acid Green
instead a greener tone is given to the black. In place of the Victoria
Black B the two other brands, 5 G, and G, of these blacks may be used.
These give equally fast blacks of a deeper and more jet black.
_Black on Wool_.--Prepare a bath with 5 lb. acetic acid, 9° Tw.; enter
the wool for one hour, then lift and add 5lb. Naphthol Black 3 B, and
1/4 lb. Indian Yellow. Re-enter the goods and boil for one hour, wash
and dry.
Many of the black dyes--Naphthol Black, Naphthylamine Blacks, (p. 092)
Naphthyl Blue Black N, Acid Black B, etc.--are capable of slowly dyeing
wool from neutral baths, that is, containing only Glauber's salt, or
rather more quickly if a little acetic acid be present. Such dyes are
very useful for dyeing heavily milled or felted fabrics, such as hat
bodies for instance, as then the dye possesses greater penetrative
properties and passes more into the substance of the fabric, which is,
therefore, better dyed through. Also they are suitable for dyeing
half-wool fabrics as will be seen on referring to the chapter dealing
with the dyeing of union or cotton-wool fabrics.
It is quite possible to dye a black on wool by using a combination of
acid and azo dye-stuffs, and below is given a recipe illustrating this
method; it is one, however, rarely adopted.
_Blue-Black on Wool_.--Prepare the dye-bath with 10 lb. Glauber's
salt, 2 lb. Patent Blue, 6 oz. Brilliant Orange, 4 oz. Amaranth, 4 oz.
Acid Violet N, 4 lb. sulphuric acid. Enter the goods at about 150° F.,
raise to the boil and work to shade; lift, wash and dry. It may be of
interest to note that by using a mixture of Azo Rubine and Acid green
good blacks can be got.
There is a range of Acid and Azo dyes which are capable of dyeing from
the usual acid baths on to wool, and yet can be developed and fixed on
the fibre to good, full blacks. Types of such dyes are Anthracene
Chrome Black F F, Diamond Black F, Chrome Patent Black D G and D G G,
Fast Chrome Black, etc. Generally the blacks dyed on wool with these
dyes are very fine, have a full, bloomy appearance, and are very fast.
They are much used in dyeing hat bodies and fine cloths which have to
be very fast to the weather.
The method of application will be gleaned from the recipes given
below.
_Black_.--Prepare a dye-bath with 5 lb. Chromotrop S, 1/4 lb. Azo (p. 093)
Yellow, 50 lb. Glauber's salt. Work for one and a half hours at the
boil, then add 4 lb. sulphuric acid. Work at the boil for another half
hour, then lift. Add to the same dye-bath 3 lb. bichromate of potash.
Re-enter the goods and work at the boil for half an hour, then lift,
rinse and dry.
_Jet Black_.--Mordant the wool by boiling for one hour in a bath made
from 4 lb. bichromate of potash and 3 lb. of tartar. Then rinse, and
dye in a bath containing 3-1/2 lb. Diamond Black, 1-1/4 lb. Alizarine
Cyanine R R R double, and 1 lb. Gambine Yellow, working at the boil
for from one to one and a half hours.
_Diamond Black on Wool_.--Mordant by boiling for one hour with 3 lb.
bichromate of potash, 1 lb. oxalic acid. Wash and dry in a bath made
with 2 lb. Diamond Black, 2 lb. acetic acid. Work at 120° F. for one
hour, then heat to boil, and work until the dye is fully fixed. Lift,
wash and dry.
A more common method of using the Diamond Black is given in the
following recipe.
_Diamond Black_.--Prepare a dye-bath with 10 lb. Glauber's salt,
2-1/2 lb. Diamond Black, 1/2 lb. Diamond Green. Boil for an hour, then
pass through a fresh bath of 2 lb. bichromate of potash for
three-quarters of an hour at the boil; wash and dry.
This gives a fine jet shade of black, quite fast to a strong milling,
and to light, alkalies and acids. Diamond Black by itself gives bluish
shades. This dye is much used in the hat-dyeing trade.
_Violet Black_.--Mordant the wool by boiling for one and a half hours
in a bath made with 3 lb. fluoride of chrome and 1 lb. oxalic acid,
then rinse and dye in a bath containing 25 lb. Alizarine Cyanine
Black G, 5 lb. acetate of ammonia, and 1 lb. acetic acid, working at
the boil for one and a half hours. A fine full shade is obtained (p. 094)
which is quite fast to acids, milling and light.
_Brown Black_.--Mordant the wool as in the last recipe, then dye in a
new bath 25 lb. Alizarine Cyanine Black G, 3 lb. Anthracene Brown,
5 lb. acetate of ammonia, and 1 lb. acetic acid, working at the boil
for one to one and a half hours.
_Jet Black_.--Mordant as in either of the above recipes, then dye in a
bath containing 20 lb. Alizarine Black S W, and 2 lb. acetic acid.
This black possesses a great degree of resistance to acid, alkali,
milling and light, and is one of the best blacks at the disposal of
the dyer.
_Reddish Black on Wool_.--Prepare the dye-bath containing 5 lb.
Chromotrop 2 B, 10 lb. Glauber's salt, and 4 lb. sulphuric acid, work
at the boil for one hour, then lift. Add to the same bath 3 lb.
bichromate of potash and 1 lb. sulphuric acid, and work half an hour
longer.
_Blue Black_.--Make the dye-bath with 6 lb. Chromotrop 10 B and 4 lb.
sulphuric acid; dye, and develop the black by adding to the same bath
3 lb. bichromate of potash and 1 lb. sulphuric acid.
_Jet Black_.--Prepare the dye-bath with 5-1/2 lb. Chromotrop S,
1/4 lb. Alizarine Yellow G G W, 10 lb. Glauber's salt, and 4 lb.
sulphuric acid. Slowly raise to the boil and work for one hour, then
add to the same dye-bath 3 lb. bichromate of potash, and 1 lb.
sulphuric acid, working at the boil for one hour.
These are but a few examples of how the Chromotrops (one of the most
interesting series of dye-stuffs at the service of the dyer) may be
used to dye blacks. They of themselves dye brilliant reds, from bright
scarlet (2 R), crimson (6 B), and purple (8 B and 10 B), to maroon and
clarets (S and S B). These being turned black on being chromed, give
various shades--blue blacks, violet blacks, and jet blacks, which have
the merit of being fast to acids, strong milling, and light in a
great degree. The blue and violet blacks may be converted to jet (p. 095)
shades by adding to the dye-bath some yellow dye-stuff, such as Azo
Yellow, Alizarine Yellow, or Gambine Yellow, which will resist the
action of the bichrome in the developing bath.
Chromotrop blacks while so very fast have the disadvantage of being
expensive, but by combining them with logwood it is possible to obtain
blacks that have a great degree of resistance to light, acids and
milling. They are in this respect much superior to pure logwood
blacks, while the cost is not prohibitive.
The following recipe will serve as an example of how these two
dye-stuffs may be combined:--
_Jet Black_.--Make a bath with 2 lb. Chromotrop S, 15 lb. Glauber's
salt, and 5 lb. hydrochloric acid. Work in this bath for one hour,
then add 2-1/2 lb. bichromate of potash, and work again for half an
hour, at the boil. Lift, rinse and dye in a new bath containing 25 lb.
logwood, 1 lb. fustic extract and 1/4 lb. sulphuric acid, working at
the boil for an hour.
_Violet Black on Wool_.--Dye the wool in the Chromotrop bath, and
develop as in the last recipe. The final dye-bath is made with 6 lb.
logwood, 8 oz. Patent Blue B, and 4 lb. sulphuric acid. By using
logwood alone blue blacks can be dyed, by increasing the proportion of
fustic a greener tone can be obtained, while by the use of a larger
proportion of Chromotrop a redder tone of black is the result.
_Jet Black_.--Make the dye-bath with 20 lb. Glauber's salt, and 6 lb.
Nyanza Black; when obtained is a good one and of solid appearance.
Alkalies turn it red, but it is fast to dilute acid and soaping.
_Black_.--Prepare the dye-bath with 10 lb. Glauber's salt, 5 lb.
oxalate of ammonia, 5 lb. acetic acid and 6 lb. Anthracene Chrome
Black F. Work at the boil for three-quarters of an hour, or until (p. 096)
the bath is exhausted of dye-stuff, then add 1-1/2 lb. bichromate of
potash and 2 lb. hydrochloric acid to the same bath and work for half
an hour longer.
The Anthracene Chrome Blacks, of which there are three brands, F, 5 B
and F E, are excellent dyes, producing very fine blacks, and owing to
the slowness of dyeing and great penetrative properties are very
suitable for dyeing hat felts and other closely woven fabrics. The 5 B
dyes more bluish shades than the F, while the F E brand gives full
black. By combining these with Anthracene Yellow B N, Anthracene Acid
Brown G, or other similar dyes, jet blacks can be got as per the
following recipe:--
_Jet Black_.--Make the dye-bath with 6 lb. Anthracene Chrome
Black F E, 5 oz. Anthracene Yellow B N, 10 lb. Glauber's salt, 2 lb.
oxalate of ammonia and 5 lb. acetic acid, after dyeing, and the
dye-bath, is exhausted of colour, add 1-1/2 lb. bichromate of potash
and 3 lb. hydrochloric acid, and boil again for half an hour. Finish
in the usual way.
One of the reasons for adding the oxalate of ammonia, is to
precipitate out any lime which may be in the water in such a form that
it will not react with the dye-stuff.
_Fast Black_.--Mordant the yarn with copperas (sulphate of iron). Dye
in a bath with 5 lb. Gambine Y, 2 lb. Acid Mauve, 2 lb. bisulphate of
soda. Proceed as described for full green.
_Blue Black_.--3-1/2 lb. Naphthylamine Black S, 10 lb. Glauber's salt,
and 5 lb. acetic acid; to fully exhaust the dye-bath add 8 lb.
bisulphate of soda.
_Jet Black_.--5 lb. Naphthylamine Black S, 1/4 lb. Fast Acid
Green B N, 10 lb. Glauber's salt, and 5 lb. acetic acid, adding 8 lb.
bisulphate of soda to exhaust the bath.
_Blue Black_.--Give a deep blue bottom in the indigo vat and dye with
2 lb. Anthracite Black B, 10 lb. Glauber's salt and 2 lb. acetic acid.
#Greys on Wool.#--The dyeing of greys follows very naturally after (p. 097)
the dyeing of blacks, for from a broad point of view greys are simply
light blacks, and any dye-stuffs that will dye black will if used in
smaller proportions give greys. There is a great variety of tone among
greys: reddish greys, bluish greys, greenish greys, and so on. They
may be dyed in a considerable variety of ways from a large number of
dye-stuffs, both natural and artificial. Of these two classes the
latter gives the best result as far as regards brightness of tone, and
as regards other properties the greys obtained from the artificial
coal-tar colours are fully equal to those from natural dyes.
A large number of recipes are in use by dyers for the production of
greys, so many that it becomes almost an impossibility to do more than
give a mere fraction of them here. However, a number of representative
recipes will be given, covering all classes of dye-stuffs capable of
being used for the purpose, and thus forming a guide to the methods of
dyeing and the proportions of dye-stuffs to be used.
_Light Grey_.--Dye at the boil for three-quarters of an hour, in a
bath containing 1 lb. perchloride of tin, 3 lb. alum, 3 oz. indigo
extract, and 2 oz. cochineal.
_Slate Grey_.--Mordant by boiling with 4 lb. alum and 1 lb. argol,
then dye with 6 lb. logwood, 6 oz. cudbear and 3 oz. indigo extract.
_Slate Grey_.--Another method is to boil the wool with 10 lb. logwood,
2 lb. Glauber's salt and 1 lb. sulphuric acid for three-quarters of an
hour, then lift, add 1 lb. copperas, and re-enter the wool, working at
the boil for three-quarters of an hour, then lift, wash and dry.
_Reddish Grey_.--Boil for an hour with 10 lb. fustic, 11 lb. cutch,
1/2 lb. bichromate of potash and 1-1/2 lb. copperas.
_Pearl Grey_.--Give a light blue ground in the indigo vat, then dye in
a new bath with 2 lb. muriate of tin and 3/4 lb. cochineal, working at
the boil to shade.
_Silver Grey_.--Prepare a bath with 3/4 lb. tannic acid; work for (p. 098)
an hour in a warm bath, then sadden with 3 lb. nitrate of iron to shade,
then lift, wash and dry.
_Pearl Grey_.--Prepare a bath with 3 lb. fluoride of chrome and 4 lb.
Alizarine Bordeaux B. Enter into the bath when cold, then heat to the
boil and work for one and a half hours, then lift, wash and dry.
_Silver Grey_.--The dye-bath is made with 3 lb. fluoride of chrome and
6-1/2 oz. Alizarine Cyanine G G, the dyeing being done as in the last
recipe.
_Greenish Grey_.--A good shade is dyed with 3 lb. fluoride of chrome,
4 oz. Alizarine Bordeaux B, and 4 oz. Diamond Flavine G, working as
given in the above recipe.
_Grey_.--Give a pale blue bottom with an indigo vat, then dye in a
bath containing 1 lb. fluoride of chrome, 1/2 oz. Diamine Fast Red F,
and 3/4 oz. Anthracene Yellow C; work at the boil for one hour, lift,
wash, and dry.
_Dark Grey_.--A very fine dark grey, almost approaching a black is
obtained by the following plan: bottom the wool with a medium blue by
means of the indigo vat, dye in a bath containing 1 lb. fluoride of
chrome, 3 oz. Diamine Fast Red F, and 3 oz. Anthracene Yellow C.
_Slate Grey_.--A good slate grey of a slightly greenish tone can be
dyed in a bath of 5 lb. acetate of ammonia, 3/4 lb. Acid Blue 4 S, and
1/4 lb. Titan Brown R, working at the boil to shade.
_Pale Slate Grey_.--The dyeing is done in a bath made with 5 lb.
acetate of ammonia, 5 oz. Acid Blue 4 S, and 1-1/2 oz. Titan Brown R,
working at the boil for one hour.
_Silver Grey_.--A very nice shade is dyed with 3 oz. Acid Blue 4 S,
1/4 oz. Titan Red, and 5 oz. acetate of ammonia.
_Silver Grey_.--A shade similar to the last is dyed in a bath
containing 10 lb. Glauber's salt, 5 lb. bisulphate of soda, and
3/4 oz. Anthracite Black R. By adding a little Thiocarmine R the (p. 099)
shade can be turned bluer in tone, while the addition of a little
Milling Yellow O, or Titan Yellow, turns it to the green side.
_Pearl Grey_.--Make the dye-bath with 10 lb. Glauber's salt, 5 lb.
acetic acid, and 3/4 lb. Naphthylamine Black D. This gives fine shades
of pearl grey.
_Bluish Grey_.--Mordant the wool by boiling in a bath made with 2 lb.
bichromate of potash, 1 lb. tartar, and 1 lb. sulphuric acid. Dye in a
bath containing 2 oz. Diamine Black (or 3/4 oz. Diamond Black and
1-1/2 oz. Alizarine Cyanine R), working at the boil for an hour and a
half.
_Grey_.--This can be dyed with 3 oz. Nyanza Black B, and 10 lb.
Glauber's salt, working at the boil.
_Reddish Grey_.--A good full shade is dyed with 1-1/2 oz. Cyanole
extra, 1/4 oz. Orange extra, 3/4 oz. Archil Substitute N, 10 lb.
Glauber's salt and 3 lb. sulphuric acid.
_Slate Grey_.--The dye-bath is made with 3 oz. Cyanole extra, 1/2 oz.
Archil Substitute N, 3/4 oz. Orange extra, 10 lb. Glauber's salt and
2 lb. sulphuric acid.
_Bright Pearl Grey_.--Prepare a dye-bath with 3/4 oz. Patent Blue,
1/2 oz. Acid Violet N, 3/4 oz. Orange G, 10 lb. Glauber's salt and
2 lb. sulphuric acid.
_Stone Grey on Wool_.--The dye-bath is made with 1/2 oz.
Chromotrop 2 R, 3/4 oz. Cyanole extra, 1-1/2 oz. Fast Acid Blue R,
3/4 oz. Acid Yellow, 20 lb. Glauber's salt, 3 lb. acetic acid. Enter
at 80° F., then warm slowly and work to shade, lift, wash and dry.
These recipes will probably be sufficient to show the lines on which
greys may be obtained in wool dyeing. It may be added that from the
Acid Blacks B, B B, and S, good greys of a violet tone may be
obtained, using from 1/2 to 3/4 oz. dye-stuff. The Naphthol Blacks
will also be found useful in the same way, while the greys from
Anthracene Chrome Blacks and the Alizarine blacks are very good and
fast.
#Red Shades on Wool.#--The number of red shades that may be dyed (p. 100)
on wool is infinite. They range over every variety of tint of red, from
the palest blush-rose to the deepest crimson, and from the most brilliant
pink to the dullest grenat shade.
It is quite impossible here to describe the dyeing of every imaginable
shade of red, while the great variety of red dye-stuffs, both natural
and artificial, adds to the difficulty of dealing in the space at
command with all the various methods and dyes that may be used in the
dyeing of reds on wool.
The methods that may be adopted for dyeing red shades on wool are many
and various, depending not only on the particular dye-stuff used, but
often on the particular shade that is being dyed. One method, which
will yield a pale and useful tint with a particular dye-stuff, would
fail if a full shade were necessary.
The greater number of red shades are now dyed by means of the
artificial dye-stuffs, as these are much easier to dye than are the
natural dyes, and they give, on the whole, more even and brilliant
shades, while as regards fastness to milling, acids, and light they
are fully equal, and in most cases superior, to the natural dyes.
#The Direct Red Dyes.#--Of this group of red dye-stuffs, Benzopurpurine,
Titan Scarlet, Diamine Fast Red F, and Benzo Fast Red are types; many
of them have been found to be very serviceable in wool dyeing. They
may be dyed either from plain baths containing common salt or
Glauber's salt, or from baths containing common salt or Glauber's salt
and a little acetic acid.
Alkaline or soap baths do not work well as a rule, and must be avoided
in wool dyeing. Generally the dye-bath is exhausted of colour, and
full shades are easily obtained, while these reds are in general
remarkable for the evenness and uniformity of tint which can be (p. 101)
produced. The reds so dyed are, on the whole, fairly fast to soaping,
and can be used for dyeing goods that have to be milled, while their
resistance to light and air is fairly good. Benzopurpurine and Diamine
Red are more or less affected by acids, but the Titan Red and some of
the more modern reds, Diamine Brilliant Scarlet, Benzo Fast Scarlets,
are all fast to acids. The fastness to washing and light of some of
them, Benzo Fast Red, Diamine Fast Red F, Titan Red, is much increased
by adding, after the wool has been dyed, 3 per cent. of fluoride of
chromium to the dye-bath, and working a little longer.
The dyeing with these colours is done at the boil, and the goods may
be entered direct into the boiling bath without fear of uneven shades
being produced. This bath may be kept as a standing one, simply adding
as each lot is dyed the necessary quantity of dye-stuff, a little
fresh water to bring the bath up to its original volume, and a
corresponding quantity of the salt originally added. The wool can then
be entered and dyed.
In place of using salt or Glauber's salt, acetate of ammonia is an
excellent assistant for this class of dyes.
The following are some recipes for dyeing various shades of red on
wool with this class of dyes.
_Scarlet_.--The dye-bath is made with 3 lb. Titan Scarlet C B, and
10 lb. acetate of ammonia. This gives a good bright shade of scarlet,
which is fast to acids and soaping, although not fast to light.
_Scarlet_.--Dye in a bath made with 3 lb. Diamine Scarlet B and 10 lb.
Glauber's salt. This yields a light shade, not so fast to acids as the
last, but equally fast to soaping and light.
_Scarlet_.--Make the dye-bath with 3 lb. Benzopurpurine 4 B, and
10 lb. Glauber's salt. This also gives a good shade of Scarlet fast to
soaping. It is turned dark blue by acids, and is not fast to (p. 102)
light. It is very largely used on underwear goods, but is not so
satisfactory for this as the Titan Scarlet C B, or Benzo Fast
Scarlet B S.
_Scarlet_.--The dye-bath may be made with 3 lb. Brilliant Congo G,
10 lb. Glauber's salt and 2 lb. acetate of ammonia. This gives a
satisfactory shade of scarlet.
_Bright Scarlet_.--The dye-bath prepared with 2 lb. Geranine G, 5 lb.
sulphate of soda, 5 lb. acetate of ammonia. Work at the boil for one
hour, then wash and dry.
_Dark Crimson_.--Prepare a dye-bath with 1-1/2 lb. Chrysophenine,
1-1/2 lb. Hessian Violet, 25 lb. salt. Heat to 150° F., enter the
goods, heat to boil and dye boiling for one hour, take out, rinse and
wash.
_Scarlet_.--A brilliant shade of scarlet can be dyed in a bath of
3 lb. Benzo Fast Red, 1 lb. Chrysophenine, 10 lb. Glauber's salt and
2 lb. acetic acid.
_Fast Red_.--Dye the wool in a bath boiling, containing 1 lb. Diamine
Fast Red F, 10 lb. Glauber's salt, and 2 lb. acetic acid, until the
bath is exhausted, then add 3 lb. fluoride of Chrome and work half an
hour longer at the boil.
_Bordeaux_.--Dye with 3 lb. Diamine Bordeaux, and 10 lb. Glauber's
salt.
_Pink_.--Dye with 2 lb. Diamine Rose B D, 10 lb. Glauber's salt and
1 lb. acetic acid.
The basic red dyes are not very numerous, and comprise Magenta,
Saffranine, Acridine Reds, Acridine Scarlets, Rhoduline Reds,
Rhodamine and Neutral Beds. For successful dyeing they require a
perfectly neutral bath. This bath should contain 10 per cent. of
Glauber's salt, and is started cold and not too strong; when all the
material has been entered the steam may be turned on and the
temperature slowly raised, the material being turned over and over.
The operation is continued only until the bath has been exhausted of
colour, when it is stopped, and the wool taken out, and washed (p. 103)
and dried. The liquor in the dye-baths may be allowed to cool down,
and then it may be used for making the dye-bath for a second lot of
goods, or it may be run away. It is best not to add the dye to the
bath all at once, but in several portions as the work proceeds. The
affinity of the wool for the basic dyes is usually so strong that if
all were added to the dye-bath at the start, then the first portion of
the goods entered might take up all, or nearly all, the colour,
leaving but little for the last portion; the consequence being that
the goods are dyed of an uneven colour, deeper in some parts than
others. This defect is remedied by adding the dye in portions,
entering the goods rather quickly, working cold, or by adding a little
acetic acid and plenty of Glauber's salt. Notwithstanding all these
precautions it is quite possible for the shades to come up somewhat
uneven. These remarks are applicable not only to the basic reds but to
the whole range of basic dyes, hence this class of dye-stuffs is but
little used in the dyeing of wool.
_Crimson_.--Make the dye-bath with 2 lb. Magenta, and 15 lb. Glauber's
salt, working as described above. This gives a fine crimson shade
which, however, is not fast to soaping or to light. The quantity of
dye-stuff given above should not be exceeded or the shades may come up
bronzy, this may be avoided if a trace of acetic acid is added to the
dye-bath.
_Crimson_.--Dye with 2-1/2 lb. of Saffranine and 15 lb. Glauber's
salt. This dyes a fine Crimson shade.
_Deep Red_.--Use 3 lb. Rhoduline Red and 10 lb. Glauber's salt.
_Scarlet_.--The dye-bath is made with 1 lb. Saffranine Prima, 1 lb.
Auramine, and 10 lb. Glauber's salt. The goods are entered into the
dye-bath at about 120° F., and well worked about, then the temperature
is raised slowly. When the dye-bath is exhausted the goods are lifted,
washed and dried. There are no pure basic scarlets, and the above and
similar combinations of a basic red and a basic yellow are the (p. 104)
only ways in which a scarlet can be dyed on wool with basic coal-tar
colours.
The basic colours are, in general, the hydrochlorides of some colour
base, and in the process of dyeing the acid constituent of the wool
fibre unites with the colour base, while the hydrochloric acid which
is liberated passes into the dye-bath.
The acid reds are a very large group of red dyes, of somewhat varied
chemical composition, which all have the property of dyeing from baths
containing Glauber's salt and sulphuric acid or acetic acid, the usual
proportions being 10 per cent. of the former, and 2 to 5 per cent. of
the acid. Some are best dyed from a bath containing bisulphate of
soda. The dyeing should be started cold, or at a lukewarm heat, then
steam should be turned on and the temperature raised to the boil, at
which it is maintained for an hour; this boiling serving to more
intimately fix the dye-stuff on the woollen fibre.
The Eosine reds, of which Eosine in its various brands, Rose Bengale,
Phloxine, Saffrosine and Erythrosine, are examples, are best dyed upon
wool from a bath containing Glauber's salt and a little acetic acid.
They do not require a very acid bath, hence the reason of using acetic
acid. The method of dyeing is that given above as for basic reds,
namely, enter into cold, or at most lukewarm bath, and raise the heat
slowly, continuing the work until the shade required has been
obtained. It is a good plan to start work in a neutral bath, and then
when the material has become thoroughly impregnated with the
dye-liquor to add the acetic acid. The shades obtained from these
Eosine reds are remarkable for their brilliance, but unfortunately
their fastness to light, washing, etc., is but slight, although it may
be increased by treating the dyed wool in a bath of alum or acetate of
lead.
Some of the acid reds, _e.g._, Acid Magenta, Acid Violet, belong (p. 105)
to the group of sulphonated basic dyes. The vast majority belong to the
group of azo dyes, which can be employed to dye from palest pinks to
the deepest crimson reds. Some dye very brilliant shades, others only
yield dull reds. Some dye shades remarkable for their fastness to all
agencies, soap, acids, alkalies, light and air; others dye shades
which may be fast to soap, but loose to acids and light. Generally
even shades are readily obtained on any kind of woollen fabric. It is
practically impossible to name all the acid reds that are known and
that may be used, but a fairly representative series of recipes will
be given.
_Ponceau_.--Wet out, then prepare a bath with 2 lb. Ponceau R, 10 lb.
Glauber's salt, 2 lb. sulphuric acid. Enter the wool in the cold,
bring to a boil and work to shade, wash and dry.
_Crushed Strawberry_.--Prepare a bath containing 10 lb. Glauber's
salt, 4 oz. Scarlet R S, 9 oz. Indigo extract, 2 oz. Orange Y, 4 oz.
sulphuric acid. Enter wool at 160° F., give four turns, raise
temperature slowly to a boil, and turn to shade, lift and wash.
_Scarlet_.--Prepare a dye-bath with 2 lb. Azo cochineal, 10 lb.
Glauber's salt, 4 lb. sulphuric acid. Work at the boil until the full
shade is obtained, then lift, wash and dry.
_Terra Cotta Red_.--The dye-bath is made from 2-1/2 lb. Fast Acid
Magenta B, 2-1/2 lb. Fast Yellow F Y, 10 lb. Glauber's salt, 2 lb.
sulphuric acid. Work at the boil to shade.
_Fast Scarlet_.--Prepare a dye-bath with 3 lb. Glauber's salt,
1-1/4 lb. sulphuric acid, 2-1/2 lb. Brilliant Scarlet 4 R. Work at the
boil for one and a half hours.
_Scarlet_.--Make the dye-bath with 2 lb. Scarlet 2 R J, 10 lb.
Glauber's salt and 2 lb. sulphuric acid. The goods may be entered at
about 150° F., and the temperature raised at the boil and maintained
at that heat for one hour, then the goods are lifted, rinsed and
dried.
The method given in the above recipes is that usually followed (p. 106)
with the acid colours. When closely woven or thick goods are being
dyed, where it is desired that the colour should penetrate well into
the substance of the goods, the following modification of working may
be adopted:--
The dye-bath is made up with the dye-stuff and Glauber's salt only,
and the goods are worked in this at the boil until they are thoroughly
impregnated with the dye-stuff liquor, then the acid is added in small
quantities at a time, and the dyeing is continued for one hour to fix
the colouring matter on the wool fibre. The goods may then be lifted
out, washed and dried.
_Scarlet_.--Make the dye-bath with 2 lb. Scarlet F R, 10 lb. Glauber's
salt and 2 lb. sulphuric acid. In place of scarlet F R, the F 2 R or
F 3 R brands may be used, the latter giving the reddest shades.
_Scarlet_.--Make the dye-bath with 2 lb. Scarlet O O, 10 lb. Glauber's
salt and 2 lb. sulphuric acid. Scarlet O dyes a yellower shade of
scarlet, while scarlets O O and O O O dye slightly redder shades.
_Scarlet_.--The dye-bath is made with 3 lb. Brilliant Ponceau 2 R,
10 lb. Glauber's salt and 10 lb. bisulphate of soda. This gives a
brilliant shade of scarlet. Brilliant Ponceau G, used in the same way,
gives a much yellower tone of scarlet, the R gives a slightly yellower
tone, while the 3 and 4 R brands dye redder shades.
_Bluish Red_.--The dye-bath is made with 2 lb. Brilliant Croceine B,
10 lb. Glauber's salt, and 10 lb. bisulphate of soda. Brilliant
croceine B B and the brand M dye redder shades of scarlet.
_Red_.--Make the dye-bath with 3 lb. Milling Red R, 20 lb. Glauber's
salt, and 5 lb. acetic acid. This is a good bright shade, and is quite
fast to soaping and milling.
_Deep Scarlet_.--Dye with 3 lb. Chromotrop R, 10 lb. Glauber's (p. 107)
salt, and 2 lb. sulphuric acid. This scarlet is very fast to milling,
acid and light.
_Red_.--Make the dye-bath with 2 lb. Victoria Scarlet R, 1 lb.
Victoria Rubine O, 10 lb. Glauber's salt, and 4 lb. sulphuric acid. A
fine deep scarlet red is obtained.
_Scarlet_.--Dye with 2 lb. Brilliant Orseille C, 10 lb. Glauber's
salt, and 3 lb. sulphuric acid. This gives a bright bluish shade of
scarlet.
_Red_.--Dye with 1 lb. Emin Red and 5 lb. bisulphate of soda.
_Scarlet_.--Make the dye-bath with 3 lb. Croceine Scarlet 3 R, 10 lb.
Glauber's salt, and 2 lb. sulphuric acid.
_Fawn Red_.--Make the dye-bath with 1-1/2 oz. Cyanole, 1-1/2 oz.
Orange extra, 2-1/2 oz. Archil Substitute N, 10 lb. Glauber's salt,
and 2 lb. sulphuric acid. This gives a nice light tint of fawn red, of
a somewhat bluish tone.
_Deep Fawn Red_.--A very deep shade of fawn red is dyed with 4-1/2 oz.
Cyanole, 2-1/4 lb. Orange extra, 1-1/4 lb. Archil Substitute N, 10 lb.
Glauber's salt, and 2 lb. sulphuric acid. The same dye-stuffs are used
as in the last, but the result is a deeper shade, of a yellow tone.
_Crushed Strawberry Red_.--Use 4 oz. Chromotrop 2 R, 2 oz. Cyanine B,
1 oz. Azo yellow, 10 lb. Glauber's salt, and 2 lb. sulphuric acid.
_Pale Lilac Rose_.--Dye with 1 oz. Chromotrop 2 R, 1/2 oz. Cyanine B,
1/2 oz. Azo yellow, 10 lb. Glauber's salt, and 2 lb. sulphuric acid.
_Deep Fawn_.--Dye with 3-1/4 oz. Chromotrop 2 R, 1-1/2 oz. Orange G,
2 oz. Cyanine B, 4 oz. Fast Acid Blue R, 10 lb. acetic acid, and
20 lb. Glauber's salt.
_Crimson_.--Make the dye-bath with 3 lb. Titan Red 6 B, 20 lb. salt,
with a little acetic acid, and work at the boil. This gives a fine
shade of crimson, fast to acids and capable of standing milling very
well.
_Deep Crimson_.--A bright and deep crimson is dyed with 4 lb. Fast (p. 108)
Acid Magenta B, 10 lb. Glauber's salt, and 3 lb. sulphuric acid, working
at the boil.
_Pale Crimson_.--Make the dye-bath with 2 lb. Fast Acid Magenta B,
10 lb. Glauber's salt, and 2 lb. sulphuric acid, working at the boil.
Level shades are readily obtained, and the dye is fast to washing.
_Deep Crimson_.--Make the dye-bath with 4 lb. Azo Fuchsine G, 10 lb.
Glauber's salt, and 2 lb. sulphuric acid. This gives a very deep shade
of crimson, of a bluish tone.
_Bluish Crimson_.--Use in the dye-bath 2 lb. Azo Fuchsine G, 10 lb.
Glauber's salt, and 2 lb. sulphuric acid.
_Pale Bluish Crimson_.--Use in the dye-bath 1 lb. Azo Fuchsine G,
10 lb. Glauber's salt, and 2 lb. sulphuric acid. This gives a very
bright shade of pale crimson. The B brand of the Azo Fuchsines gives
slightly bluer shades than the above.
_Deep Crimson_.--A very solid crimson is dyed in a bath containing
3 lb. Azo Red A, 2 oz. Orange extra, 2 oz. Cyanole extra, 10 lb.
Glauber's salt, and 2 lb. sulphuric acid. Work at the boil.
_Bright Crimson_.--A fine bluish crimson can be dyed on wool with
4 lb. Azo Red A, 10 lb. Glauber's salt, and 10 lb. bisulphate of soda.
Work at the boil.
_Deep Crimson_.--A good shade can be dyed with 6 lb. Amaranth, 10 lb.
Glauber's salt, and 10 lb. bisulphate of soda, working at the boil.
_Brilliant Pale Bluish Crimson_.--A really brilliant shade, bordering
on a violet red, is dyed in a bath containing 1-1/2 lb. Fast Acid
Violet R, 10 lb. Glauber's salt, and 2 lb. sulphuric acid.
_Bluish Crimson_.--Make the dye-bath with 3 lb. Croceine Scarlet,
10 lb. Glauber's salt, and 2 lb. sulphuric acid. This gives a good
full shade of a bluish tone and very bright.
_Bluish Crimson_.--Dye with 3 lb. Chromotrop 6 B, 10 lb.
Glauber's salt, and 3 lb. sulphuric acid. This gives a fine tint, (p. 109)
very fast to acids, milling and light.
_Purple_.--Make the dye-bath with 3 lb. Chromotrop 10 B, 10 lb.
Glauber's salt, and 3 lb. sulphuric acid.
The Chromotrops are remarkable for the fulness of the shades they dye,
the brightness of their tint, and their fastness to acids, washing and
light.
_Purple_.--Use 4 lb. Azo Fuchsine B, 10 lb. Glauber's salt, and 2 lb.
sulphuric acid.
_Bluish Purple_.--A very dark shade of purple is dyed with 4 lb. Azo
Acid Violet 4 R, 10 lb. Glauber's salt, and 2 lb. sulphuric acid.
#Bordeaux Reds#.--These are shades that lie intermediately between the
scarlets and the crimsons. They are in general duller than the
scarlets, and have a more solid and fuller look; while they are less
blue in tone than the crimson. They can be obtained from a large
variety of dye-stuffs, and the recipes given below may be regarded as
typical examples.
_Bright Bordeaux Red_.--Make the dye-bath with 1 lb. Azo Bordeaux,
10 lb. Glauber's salt, and 2 lb. sulphuric acid, working at the boil
to shade. This is a very bright shade, of a somewhat bluish tone.
_Cherry Red_.--Make the dye-bath with 2-1/2 lb. Fast Acid Magenta B,
2-1/2 lb. Fast Yellow, 10 lb. Glauber's salt, and 2 lb. sulphuric
acid. This gives a fine deep shade.
_Bright Cherry Red_.--A very yellow shade of red, fast to milling, is
dyed by making a dye-bath with 1-1/2 lb. Anthracene Yellow C, 3 lb.
Diamine Fast Red F, 10 lb. Glauber's salt, 5 lb. acetate of soda, and
2 lb. bisulphate of soda. Work at the boil for one hour, then lift,
add 3 lb. fluoride of chrome, re-enter the wool and work half an hour
longer; wash and dry.
_Deep Bordeaux Red_.--The dye-bath is made with 4 lb. Diamine Fast
Red F, 5 lb. acetate of soda, and 3 lb. bisulphate of soda. Work (p. 110)
at the boil for one hour, then lift, add to the bath 3 lb. fluoride of
chrome, re-enter the goods and work again for half an hour; lift, wash
and dry.
_Bright Cherry Red_.--Make a dye-bath with 4 lb. Benzo Fast Red,
10 lb. Glauber's salt, and 2 lb. acetic acid. Work at the boil for one
hour, then lift, add 3 lb. fluoride of chrome, re-enter the goods and
work for half an hour longer; wash and dry.
_Cherry Red_.--Make the dye-bath with 2 lb. Azo Fuchsine G, 1-1/2 lb.
Fast Yellow, 10 lb. Glauber's salt, and 2 lb. sulphuric acid. Work at
the boil for one hour.
_Bluish Bordeaux Red_.--For a very fast shade use 8 oz. Fast Acid
Violet R, 8 oz. Orange G, 3/4 oz. Patent Blue B, 10 lb. Glauber's
salt, and 2 lb. sulphuric acid. Work at the boil for one hour.
_Bright Bordeaux Red_.--A good bright and fast shade of red is dyed
with 3-1/2 lb. Emin Red and 7 lb. bisulphate of soda. Work at the boil
for one hour, then lift, add 3 lb. fluoride of chrome, work for
three-quarters of an hour, then lift, wash and dry.
_Bordeaux Red_.--Use 3 lb. Titan Scarlet D, 1/4 lb. Titan Brown O, and
20 lb. salt. Work at the boil for one hour, then lift, wash and dry.
#Claret Reds.#--Claret reds are very useful shades and are great
favourites of the dress-loving public. They are dark reds of a yellow
tone, and can be dyed upon wool in a variety of ways, of which the
following recipes just indicate a few.
_Claret_.--Make the dye-bath with 4 lb. Milling red R, 10 lb.
Glauber's salt, and 4 lb. sulphuric acid.
_Claret_.--Use 4 lb. Archil Substitute N, 10 lb. Glauber's salt, and
2 lb. sulphuric acid.
_Claret_.--Make the dye-bath with 2 lb. Bordeaux B L, 10 lb. Glauber's
salt, and 2 lb. sulphuric acid.
_Claret_.--A deep shade is dyed with 2-1/2 lb. Victoria Scarlet R, (p. 111)
2 lb. Victoria Rubine O, 1 oz. Cyanine Scarlet R, 2 lb. Victoria
Rubine O, 1 oz. Cyanine B, 10 lb. Glauber's salt, and 2 lb. sulphuric
acid.
_Claret_.--A fine deep shade is dyed with 2 lb. Azo Red A, 1/4 lb.
Orange extra, 1/4 lb. Cyanole, 10 lb. Glauber's salt, and 2 lb.
sulphuric acid.
#Maroon Reds.#--From clarets to maroons is not a wide interval, they are
both dark shade reds, the former tending to a yellow tone, the latter
to a more bluish shade of red. A few recipes will be given to show
some of the best methods of dyeing maroons.
_Maroon_.--Use 6 lb. Amaranth B, 10 lb. Glauber's salt, and 2 lb.
sulphuric acid. This gives a fine bright shade.
_Deep Maroon_.--Make the dye-bath with 4-1/2 lb. Fast Acid
Violet 10 B, 80 lb. Glauber's salt, and 3 lb. sulphuric acid. This
gives a fine blue shade of maroon of great depth.
_Maroon_.--The dye-bath is made with 3 lb. Azo acid violet 4 R, 1 lb.
Fast Yellow S, 1-1/2 oz. Fast Green Bluish, 10 lb. Glauber's salt, and
2 lb. sulphuric acid.
_Deep Maroon_.--Make the dye-bath with 2 lb. Acid Magenta, 1/2 lb.
Orange O, 1/2 lb. Patent Blue V, 10 lb. Glauber's salt, and 2 lb.
sulphuric acid.
_Deep Maroon_.--Make a dye-bath with 3 lb. Azo Acid Rubine, 1-1/2 oz.
Acid Black B B, 10 lb. Glauber's salt, and 2 lb. sulphuric acid.
_Maroon_.--The dye-bath is made with 3 lb. Milling Red B, 1-1/2 oz.
Naphthol Black 4 R, 10 lb. Glauber's salt, and 3 lb. sulphuric acid.
_Deep Maroon_.--Make the dye-bath with 1-1/2 lb. Victoria Scarlet R,
13 oz. Victoria Rubine O, 1/2 lb. Victoria Yellow, 2 lb. Keton Blue G,
10 lb. Glauber's salt, and 3 lb. sulphuric acid.
_Bright Red_.--A good shade is dyed with 4 lb. Lanafuchsine S G, and
10 lb. bisulphate of soda. Lanafuchsine S B dyes somewhat bluer
shades.
_Fast Red_.--Dye with 4 lb. Milling Red B, 10 lb. Glauber's salt, (p. 112)
and 2 lb. sulphuric acid.
_Bright Scarlet_.--Dye with 3 lb. Brilliant Cochineal 2 R, 10 lb.
Glauber's salt, and 3 lb. sulphuric acid.
_Deep Scarlet_.--Dye with 3 lb. Brilliant Ponceau 4 R, 10 lb.
Glauber's salt, and 2 lb. sulphuric acid.
#Pinks.#--_Pink_.--Use 1-1/2 oz. Erythesine D, and 5 lb. acetic acid.
These two pinks are very much alike and are very bright.
_Bluish Pink_.--Use 1-1/2 oz. Rose Bengale and 5 lb. acetic acid.
_Pink_.--Make the dye-bath with 3 oz. Azo Cochineal, 10 lb. Glauber's
salt, and 2 lb. sulphuric acid.
_Bluish Pink_.--Make the dye-bath with 3/4 to 1 oz. Fast Acid Violet R
and a little Orange G, 10 lb. Glauber's salt, and 2 lb. sulphuric
acid.
_Pink_.--By using 1-1/2 oz. Fast Acid Violet R, 3/4 oz. Orange G,
10 lb. Glauber's salt, and 2 lb. sulphuric acid, a good full pink is
obtained.
_Bluish Pink_.--Use 2 oz. Fast Acid Violet R, 10 lb. Glauber's salt,
and 2 lb. sulphuric acid.
Many of the other acid reds may be used for dyeing pinks if from 2 to
4 oz. of dye-stuff be used.
_Pink_.--Use in the dye-bath 1-1/2 oz. Diamine Fast Red F, 5 lb.
acetate of soda, and 3 lb. bisulphate of soda.
_Coral Red_.--Make the dye-bath with 1/2 lb. Diamine Scarlet B, 10 lb.
Glauber's salt, and 1 lb. acetic acid.
_Dark Cherry Red_.--The dye-bath is made with 2-1/2 lb. Orange G G,
1 lb. Brilliant Orseille C, 3/4 oz. Cyanole extra, 10 lb. Glauber's
salt, and 2 lb. sulphuric acid.
_Deep Crimson_.--Use in the dye-bath 4 lb. Brilliant Orseille C,
1-1/2 oz. Cyanole extra, 3 oz. Orange G G, 10 lb. Glauber's salt, and
2 lb. sulphuric acid.
_Scarlet_.--Make the dye-bath with 4 lb. Lanafuchsine S G, and 10 lb.
bisulphate of soda. Work at the boil to shade.
_Crimson_.--Make the dye-bath with 4 lb. Lanafuchsine S B, and (p. 113)
10 lb. bisulphate of soda. Work at the boil to shade.
The Lanafuchsines, of which there are three brands, S G, S B, and 6 B,
dye very good level shades of red from scarlet to crimson, which are
of good fastness to milling, acids and light.
_Salmon_.--Use 1/2 lb. Rhodamine B, 1/4 oz. Naphthol Yellow S, 10 lb.
Glauber's salt, and 2 lb. acetic acid.
_Rose Red_.--Use 1/4 lb. Lanafuchsine S B, 3 oz. Lanafuchsine S G,
10 lb. Glauber's salt, and 1 lb. sulphuric acid.
_Salmon Red_.--Use 1-1/2 oz. Lanafuchsine S G, 1/4 oz. Fast Yellow S,
10 lb. Glauber's salt, and 1/2 lb. sulphuric acid.
_Deep Crimson_.--The dye-bath is made with 2 lb. Naphthol Red C, 9 oz.
Acid Magenta, 3/4 oz. Cyanole extra, 10 lb. Glauber's salt, and 2 lb.
sulphuric acid.
_Purple Red_.--Dye with 2-1/2 lb. Naphthol Red C, 3/4 lb. Acid
Magenta, 1 oz. Cyanole extra, 10 lb. Glauber's salt, and 2 lb.
sulphuric acid.
_Bordeaux Red_.--Dye with 4 lb. Lanafuchsine S B, 1 oz. Orange extra,
10 lb. Glauber's salt, and 2 lb. sulphuric acid.
_Fawn Red_.--Dye with 1/4 lb. Orange G G, 3 oz. Lanafuchsine S B,
1/2 oz. Cyanole extra, 10 lb. Glauber's salt, and 2 lb. sulphuric
acid.
_Salmon_.--Prepare the dye-bath with 1/4 oz. Fast Acid Violet R,
1/2 oz. Orange G, 10 lb. Glauber's salt, 1 lb. sulphuric acid. Work at
the boil to shade.
The mordant reds are fairly numerous, and include both natural and
artificial red dye-stuffs. The principle or property on which the
application of this group of dye-stuffs to the dyeing of textile
fabrics depends is that they are of an acid character and combine with
metallic oxides, like those of iron, aluminium, or chromium to form
insoluble coloured bodies, or "colour lakes" as they are called. The
shade or tint of these colour lakes depends, firstly, upon the (p. 114)
dye-stuff, and, secondly, upon the metallic oxide. Thus Alizarine with
alumina gives a scarlet, with chrome a dark red, and with iron a dull
violet. Alumina and chrome are the metallic mordants most commonly
used in the dyeing of reds; sometimes tin is used, but never iron.
The coal-tar colour makers have placed at the service of dyers a great
variety of mordant dyes, which may be classified somewhat roughly into
groups, according to their chemical composition. The first group is
called phenolic colours. These contain the group, or radical OH,
hydroxyl, once or oftener. It is to the presence of this group that
they owe their acid character and the property of combination with
metallic oxides. To this group of dye-stuffs belong such dyes as
Alizarine, Alizarine Cyanine, Anthragallol, Gambine, Coerulein, and
some others. The natural red dye-stuffs, Cochineal, Brazil-wood,
madder, etc., probably belong to this class.
None of these are essentially dyes of themselves, and used alone will
not dye any fibre, it is only when they are brought into combination
with the mordant that they will dye the wool fibre.
The next group may be called hydroxy-azo dyes, and are quite of modern
introduction. They are azo dyes, one of whose constituents is a body
like salicylic acid, amido-benzoic acid, dihydroxy-naphthalene-sulpho
acid, which contain the group OH, hydroxyl with carboxyl COOH. The
first group imparts phenolic characters, while the second gives true
acid properties, and both of these acting together cause the dyes to
be able to form colour lakes with metallic oxides. There is one point
of difference between the two groups of dyes, the phenolic dyes are as
a rule not dyes of themselves, some of them are practically free from
colour, and it is only when brought into combination with the metallic
oxide or mordant that they form a colour and dye a fibre. On the (p. 115)
other hand the azo mordants are in general colouring matters, and can
be used to dye wool without the aid of a mordant, the latter only
serving to make the colour faster to light, acids, milling, etc., and
it often has no material effect on the shade or tone of colour being
dyed. Alizarine Yellow G G, Gambine Yellow, Anthracene Yellow, Chrome
Violet, are examples of such dyes.
There are, however, some dyes (such as the Chromotrops, Azofuchsine,
Anthracene Acid Browns, etc.) on which the mordant has a marked
effect.
The methods adopted in practice for the application of this class of
dyes are many and varied. The mordants used are alum, alumina
sulphate, acetate of chrome, chrome alum, fluoride of chrome, ferrous
sulphate and tin chloride, while, in addition, along with these true
mordanting materials, assistant mordants are used, such as argol,
tartar, tartaric acid, lactic acid, lignorosine, oxalic acid and
sulphuric acid.
The mordanting may be done either b
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