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





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