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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 deg. 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 deg. 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 deg. to 160 deg. 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 deg. 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 deg. 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 deg. 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 deg. C., and then for twenty minutes in clear water
at 60 deg. 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 deg. 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
haematoxylin 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 fuer
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 deg. 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, h





Next: Red Shades On Wool

Previous: Dyeing Machines



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