Dyes and dyeing

by Charles Ernest Pellew

DYEING DIRECTIONS

Dye-bath.—The color must first be dissolved in water, care being taken not to leave any undissolved lumps or specks of color floating around in, or settled at the bottom of, the dye-bath. For this reason it is generally best, in all dyeing operations, first of all to make a decidedly strong solution of the color, by dissolving a considerable quantity of it (depending of course on the amount of goods to be dyed) in hot water, in a pitcher or saucepan. In the dyehouse this would be called a “stock solution,” and would always be made of a definite strength,—say five parts of color to one hundred of water—and kept well covered up. Sometimes in hot weather it would be treated with a little preservative like benzoate of soda, so that it could be used at any time it was needed. When this color solution is added to the dye-bath, it should always be carefully strained through a piece of cheesecloth or any other fine medium that will catch the specks and undissolved lumps. Otherwise spots are liable to appear, on the finished goods, which it is almost impossible to eradicate without stripping off every trace of color from the dyed material.

Water.—The dye-bath is prepared with plain water. The amount necessary for each lot of goods can only be told by experience. For some classes of dyes, like the Acid colors and the Basic colors, to be described later, the quantity of water makes but little difference. But for dark shades with these Salt colors it is best not to have more than enough water to thoroughly soak, and comfortably cover, the wetted goods, with enough room to stir and turn them easily. The dye-bath is now set on the stove to warm up and, when dyeing light or medium shades, some soap is usually dissolved in it. This is not absolutely necessary but helps to make the color go on more evenly, and penetrate the fibres better.

Soap.—For dyeing purposes in general, any pure, carefully made soap acts satisfactorily. For silk dyeing, and especially for silk finishing, it is said that greater lustre can be gained with olive oil (Castile) soap. But when this cannot be obtained, Ivory soap or Pears’ soap or, in fact, any good brand of bath or toilet soap will do almost as well. For the washing and finishing of wool and silk the use of strong laundry soaps should be avoided if possible, because they usually contain alkali, in the form of borax or of carbonate of soda, which is liable to “tender the goods.” For cotton and linen dyeing and finishing, this does not make any difference. The easiest way to add the soap to the dye-bath is to use it in one of the wire soap-shakers, which has a convenient handle, and holds half a cake or even a whole cake of soap at one time.

Even Dyeing.—The goods should be well washed, rinsed, and wrung out, so as to be sure that they are free from dirt and grease, and have been thoroughly and evenly wet. They are then placed in the dye-bath, completely under the liquid, and stirred round and round and turned over and over with the dye-sticks. The chief objects in stirring are, first, to prevent part of the goods from resting on the bottom and then getting more heat than the rest of the material, in which case, naturally, it will become darker when finished; and second, to prevent the outside portion of the goods from getting more color than the inner portions. Accordingly the goods, when placed in the dye-bath, must be well opened up and, excepting when deliberately making patterns by the method described later under the name of “Tied and Dyed Work,” they should not be tied or entangled in knots or bunches. Every part must be equally exposed, by the turning and lifting and stirring, to the action of the color solution.

If only light shades are desired, the goods are heated and turned until the proper shade has been reached—remembering always that, unless the color has been boiled on, it is likely to be only a stain which will wash off easily.

Salt.—For full and indeed for medium shades, it is customary to add to the dye-bath some agent—usually table salt or, when the shade is not very dark, phosphate of soda—which will make the color less soluble in the dye-liquor and will tend to throw it on the fibre. For, after all, there is comparatively little affinity between the cotton fibre and the dyestuff (far less than between silk or wool and the Acid or Basic colors), and when a skein is warmed or even boiled in the dye-bath a large proportion of the color remains in the liquid. The bath is not “exhausted” as the dyers say. Hence, if we try to dye full shades with these colors dissolved in water only, or in soap and water, it can only be done by using large quantities of the dyestuff, most of which will be wasted in the spent dye-liquor.

For dark shades, then, where there is little danger of uneven dyeing, the goods are usually dyed for a short time with the color dissolved in hot water. And then, to deepen the shade, the goods are lifted, and common salt added in considerable quantities, three or four tablespoonfuls to the gallon, and stirred round till it is dissolved. Then the goods are put back and well boiled for half an hour or so, before the dyeing is considered complete. The presence of salt, by increasing the temperature of the boiling bath, also helps to make the dyed goods fast to washing.

Soap cannot be used in the presence of so much salt for fear of its depositing on the fibre in spots and so causing trouble. For medium shades, however, where it is well to use soap in the dye-bath so as to have the color go on the fibre evenly, a little phosphate of soda is often employed instead of salt, one or two tablespoonfuls to the gallon, to diminish the waste of color, without making the soap insoluble.

For the darker shades it is particularly important to thoroughly boil the goods for half an hour or more, before taking them out of the dye-bath. Otherwise the dyestuff will not penetrate the fibre, but will simply stain the surface, and will not only be easily washed off, with very mild soaping, but, when dry, will be apt to crack and rub.

Finishing.—After the materials have been dyed as just described, they should be taken out of the dye-bath, rinsed with water to wash off the excess of dye-liquor, and then shaken out and dried.

When used in this way the best dyes of this class, such as those listed a little further on, will give, on cotton and linen, shades that are very fast to light, and fairly fast to washing. On wool and silk the shades are fast to both light and washing. For purposes of comparison it may be stated here what is generally meant by these terms.

Fastness to Light.—The test for light-fastness is usually made by partially covering a dyed skein with a piece of wood, or heavy piece of blotting paper, and exposing it to direct sunlight, back of a window with southern exposure. At intervals the skein is taken out and the color studied, and it is then easy to see whether any change has taken place in the portion of the goods exposed to the light. If the goods have faded appreciably in the space of one week, the dyestuff is considerednot fast.

If the color changes after two weeks’ exposure, but not after one week, it is to be consideredfairly fast.

If it stands for two weeks but fades in four weeks it is to be calledfast.

And if it resists, without appreciable change, the action of the summer sunlight for full four weeks, it is calledvery fast.

It should be remembered, in this connection, that the comparative fastness to light depends largely (a) upon the materials to be dyed, and (b) upon the depth and shade of color used in the test. For instance, if a skein of heavy cotton yarn, and one of very fine, brilliant, artificial silk are dyed the same color, and exposed to light under the same conditions, the cotton skein will hold its color longer than the silk. The latter, being semi-transparent, allows the sunlight to pierce it through and through, while the more opaque cotton gives some distinct protection to the color that has penetrated beneath the surface. So, too, a dark shade of any given color will stand the light much better than a very light or delicate shade, for the same general reason. The color beneath the surface is protected from the direct action of the sun’s rays by the surface color.

Fastness to Washing.—The test for washing-fastness is made somewhat differently. A skein dyed a full shade with the color is twisted up with two white skeins, one of wool and the other of cotton, and the three are thoroughly scoured for ten minutes in a strong bath of good quality laundry soap, heated to 140°F. This temperature is uncomfortably hot for the hands and yet is well below the boiling point. A fast color is one where, with this treatment, neither the soap liquor nor either one of the skeins becomes colored.

If the soap liquor is colored but neither one of the skeins, the dye is calledfairly fast.

If the soap bath is tinged, and one or the other of the skeins becomes colored at the same time, the dye is considerednot fast.

It must, however, be borne in mind that before making this washing-test, all excess of dye-liquor must first be removed by thorough rinsing. And it should be remembered that even the fastest of the Salt colors, as well as of the Acid and Basic colors described later, when applied directly to the fibre, without mordanting or after-treating, are never as fast to washing as those where the dyestuff is fixed or developed in an insoluble form in the fibre, by the action of the air, as are the Sulphur and Vat colors—or by the action of mordants, as with the Alizarine colors—or by after-treatment with certain special chemicals, as with the Salt colors in the process described below. All dyes can, sooner or later, be dissociated from the fibres to which they are attached. But if they are in an insoluble condition they drop off in the form of a powder, and are washed clean off, and leave sharp, clear outlines on the dyed goods. If, however, they have gone on in solution they will go off in solution, and are liable tobleed, and stain light-colored fibres near them.

The earlier dyestuffs of this class were deservedly criticised as being, even when carefully applied, much given to bleeding, and also distinctly fugitive to the action of sunlight.

Of late years the quality of these dyestuffs has greatly improved, and the best of them, like those mentioned below, when carefully dyed on cotton, are fast, if not very fast to light, although for washing the very best can hardly be classed even as fairly fast, without after-treatment.

List of Selected Dyestuffs.—

Badische—	Oxamine Fast Red, F
	Cotton, Yellow, G I
	Stilbene Yellow, G K
	Oxamine Blue, B
	Cotton Black, E, extra
Cassella—	Diamine Fast Red, F
	Diamine Fast Yellow, G G
	Diamine Fast Blue, F F G
	Diamine Fast Black, F
Elberfeld—	Benzo Fast Red, 8 B L
	Benzo Fast Yellow, 4 B
	Brilliant Fast Black, 4 B
	Pluto Black, F, extra
Kalle—	Naphthamine Fast Red, H
	Naphthamine Fast Yellow, 2 G L
	Naphthamine Fast Blue, 4 B L
	Naphthamine Fast Violet, R L
	Naphthamine Direct Black
Metz—	Dianil Fast Scarlet, 4 B S
	Dianil Orange, G
	Dianil Yellow, O O
	Dianil Fast Blue, 3 B
	Dianil Fast Black, conc.

As above mentioned, even the very best dyes belonging to this class of Salt colors, give on cotton and linen results only “fairly fast” to washing. As the modern laundress is not averse to using stronger agents than good laundry soap in her washtub, and not infrequently indulges in considerable amounts of washing soda (sodium carbonate) and even of bleaching powder, to clean quickly a dirty piece of goods, dyes that are “fairly fast” according to the regular standard, will, in practice, need some care spent on them if they are to hold their color for long periods. Against light the best ones are almost as fast as any dyes known, but none of them are a match for the Sulphur colors, or especially the Vat colors, when exposed to severe washing.

After-treatment.—The professional dyer, who is occasionally called upon to produce fast colors with these dyes, and even with the inferior members of this class, has found various methods of after-treatment, by which the colors are rendered more permanent.

A favorite process, where the dyer is enough of a chemist to carry it out, consists of making an entirely new dyestuff in the fibre, generally of an entirely different shade, and with much greater power of resistance to washing and to light, by treating the dyed goods first with a mixture of sodium nitrite and of sulphuric acid, and, after this, passing them through a solution of some organic chemical such as carbolic acid, alpha- or beta-naphthol, or others known as developers.

This process, known as “diazotizing and developing,” is considerably used in the trade, especially for various shades of black, but is too complicated and delicate for craftsmen in general.

A simpler process is to warm the dyed goods for five or ten minutes in a weak solution of the orange-colored salt, bichromate of potash, acidified with a little acetic acid—or of the not uncommon chemical, sulphate of copper, long known to chemists as blue vitriol.

When the best dyes are used, like those in the preceding list, it is not often necessary to use either of these reagents. But when, as sometimes happens, one is obliged to use dyes of this general class, bought at the country store without a chance of knowing how fast they are, it is well to know about it. For a piece of goods the size of an ordinary linen skirt, the after-treating bath would be made as follows: In two and a half gallons of hot water, dissolve two tablespoonfuls of sulphate of copper, one tablespoonful of bichromate of potash, and two teaspoonfuls of ordinary acetic acid (equivalent, say, to three or four teaspoonfuls of strong vinegar). The goods, after dyeing and rinsing, but before drying, should be soaked in this bath and heated for ten minutes until not far from the boiling point. They should then be taken out, rinsed carefully, and dried. This after-treatment does not benefit every single color of this class, but it helps greatly the fastness to light and to washing of almost all of them. The chief objection to it, besides the time and expense, is that the shade of the finished goods is often considerably changed by the process.

Properties and Uses of the Salt Colors.—Generally speaking, the shades produced by the individual members of this group cover all the colors of the rainbow and include several good greys. It is hard, however, to get a full deep black on cotton or linen with these dyes, without using the “diazotizing and developing” process of after-treatment. The dyes go on the fibre in a soluble form, and unless a developing process like this is used they combine directly with the fibre, and do not form a coating or layer upon it, as do some of the “developed” dyestuffs. Accordingly, no matter how fully or how deeply we dye a piece of yarn or cloth with a black dye of this class, the finished goods will showgrey, a very dark grey, to be sure, but still grey, and not a flat, heavy, true black. The color of most of the salt blacks is greatly improved, however—as well as their fastness to light and washing—by soaking the dyed goods, after rinsing, in a solution containing four or five spoonfuls of formaldehyde to the gallon.

This same property, however, of combining directly with the fibre, makes the colors brighter and more brilliant than many of the other classes, especially in the lighter shades. Accordingly for bright, pretty shades of pinks, blues, yellows, and of mixed shades, fast to light, but not very fast to washing, very easily and simply applied, these colors are extremely valuable. For instance, in dyeing large quantities of bright colors on calico or cheesecloth, for some special occasion, as a pageant or spectacle, these are the colors to use.

Another great advantage they possess is that they dye true; that is, they do not alter their color when exposed to the air, and the color of the finished goods can be fairly estimated from the color of the dye-bath.

Accordingly, the student is strongly urged to practise the art of dyeing with these colors. They are cheap and can be readily obtained, although not always of the very best quality, under the name of Diamond Dyes for cotton, ezy dyes, etc., from druggists and grocerymen all over the country.

They can be easily applied to cheesecloth, muslin, and other inexpensive materials, and if care is taken to soak and boil the goods thoroughly, to linens and heavy cottons. In case of necessity they can be used on wool and silk, but, as a rule, their use is limited to vegetable fibres. They are particularly valuable to amateur dyers and to beginners in the art, because they have great “levelling” power; that is, it is easy to dye evenly with them.

On the other hand, it is a nuisance, oftentimes, to have to boil the goods, and even then the colors are not really fast to washing. At any rate, before proceeding to the study of the more permanent but more complicated Sulphur and Vat colors, the art of dyeing even and rainbow shades and at least the beginnings of the art of combining and matching shades should be carefully and conscientiously worked out with these often despised, but really very useful and valuable, Salt colors.

Chapter IV
THEORY AND PRACTICE OF COLOR DYEING

Directly the student has mastered the instruction contained in the three previous chapters, and can use the dyeing apparatus and the unmixed dyestuffs so as to get reasonably fast colors on cotton and linen goods, it is time to attack the more difficult subject of dyeing to shade. This art is not an easy one, by any means, and only a few fundamental principles can be learned from a book. To make any real progress in it, constant and continuous practice is necessary; even then, unless the student is naturally gifted with an eye capable of readily detecting any changes of color, and has trained it to distinguish and identify the causes of such changes, little success in the matching of colors can be hoped for.

This does not mean, however, that unless a dyer can match shades perfectly, he cannot turn out very interesting and, indeed, beautiful results. But it does mean that he will find it difficult, if not impossible, to reproduce such results, and will be frequently handicapped in trying to utilize his dyeing skill and knowledge commercially.

The beginner thinks—not unnaturally perhaps—that in order to get any considerable variety of shades it is necessary to have on hand a large and varied assortment of dyestuffs; and it is consequently a surprise to find that skilled workers keep in stock chiefly a good supply of blue, yellow, and red only. Black is convenient and useful, but not essential, excepting for special purposes. By mixing these three “primary” colors it is possible to get every conceivable shade needed. And another point, which will be emphasized below and which is also likely to be a surprise, is that practically every pretty and agreeable shade, no matter how delicate, is composed of all three of these primary colors. Blue and yellow produce green, blue and red produce violet, and yellow and red produce orange, while the addition of the third or “complementary” color to any of these combinations of two makesgrey, when all three colors are perfectly balanced, and when one color or another predominates, it is greyed and softened by the presence of small quantities of the other two.

Experiments with Single Colors

The way to study color dyeing is, first of all, to get a clear idea of the effect of different strengths of each of these three primary colors in producing both light and dark shades of a single color. This can be easily accomplished with the red, blue, and yellow of the Salt dyes described in the last chapter. Dissolve each color separately and keep them in separate dye-pots so that you can readily dye pieces of cheesecloth or other cheap, easy-dyeing materials any light, medium, or dark shade, to serve as a basis for future comparisons.

DIAGRAM OF PRIMARY COLORS

Two color shades—	Red + Blue =		Violet
	Red + Yellow =		Orange
	Yellow + Blue =		Green
Complementary colors—	Red + Blue + Yellow =		Grey
	Red + Green =	}
	Blue + Orange =	}	Grey
	Yellow + Violet =	}

Even Dyeing.—First wet the cloth or yarn thoroughly by soaking in hot water, then rinse well and wring it dry—if necessary, using a wringer. The dyestuff should already be carefully dissolved in a little boiling water. Pour some of this solution (not too much, for the shades should all be pretty light) into the dye-pot half full of lukewarm water. Then quickly and wholly immerse the wet material, stirring and working about with the dye-sticks, and let the whole heat steadily until it boils. After a few minutes’ boiling take out the material and rinse in cold water until it stops bleeding. When this is carefully done, good, even, and smooth shades will result.

Shaded Effects.—Of more real interest, although an abomination to most professional dyers, are the shaded effects. Instead of trying to get even, smooth colors, the cloth is intentionally dyed unevenly to get effects of light and shade in the color, otherwise impossible. This does not mean that a skein or piece of cloth badly dyed or discolored by some accident or carelessness should be proudly exhibited as a piece of really artistic dyeing, as is done occasionally, by some workers, with painful results. It is only when the work is done carefully and thoughtfully that shaded or so-called “rainbow” effects may be obtained upon skeins, basket materials, and cloth, which are distinctly interesting and beautiful, though very different from the regular work of the professional dyers.

Many methods of obtaining unique results in this work will occur to the student, after some practical experience. Perhaps the best way to begin is to take a piece of cheesecloth, cut in the form of a scarf—say two yards or so in length—and hemmed on both ends, if it is to be kept for exhibition or future use. Before it is wet, tie it in a rather tight knot in the middle, or, if the scarf is long enough, two knots about six or eight inches from each end. For this first piece tie a very simple knot by merely folding the scarf over on itself and pulling the goods tight. Then wet the cloth thoroughly and dye quickly in the boiling dye-liquor; rinse off, and untie the knots. The open part of the cloth will be found dyed the full strength, and where there were knots there will be shaded places varying from the full color down to white.

Another method is to take the wetted scarf in the middle and gradually lower the ends into the hot dye-liquor, stopping just before the middle reaches the dye. If carefully done this will give regularly shaded effects running from white or very light at the centre, to heavy, full shades at the ends. Of course, if preferred, the ends can be kept out of the dye-liquor and the middle portions immersed. This will give a scarf that is dark in the centre and light at each end—which is not so good a color arrangement, ordinarily, as the light centre and dark ends.

The same can be done with a square piece of cloth, well wetted: this will shade in an interesting manner, if held in the middle and dipped slowly and gradually. Further developments of this work, known as “Tied and Dyed Work,” are described in a following chapter.

Experiments with the Secondary Colors

After the above methods have been fairly mastered, the student should make some experiments in which two of the primary colors are mixed together, or better, superimposed one on the other to show the “secondary” shades produced by these combinations. This can be done by mixing the colors two by two, until three baths of green, violet, and orange respectively are formed as before. Then try dyeing first for even colors and later for the shaded effects.

The most interesting experiments in this line are made by the so-called “double shading” method. Here the same baths of straight primary colors—red and blue and yellow—should be used as in the earlier experiments; but the goods are first dyed in one bath, and then after-dyed or “topped” in a second color.

A scarf of cheesecloth is good for a first attempt. This, well wet, is held at one end and very slowly lowered into the hot bath, until all but about six inches of the entire length is immersed in the dye. This much is left free from color. Try a blue dye color for this series of shades, fading evenly and smoothly from the deepest full blue at one end to a pure white at the other.

After rinsing with water till the bleeding is over, reverse the scarf, holding it by the opposite end, and lower it slowly and gradually into a bath of, let us say, yellow, keeping about six inches out of the dye as before. This will produce a scarf shaded from clear blue at one end to clear yellow at the other end and showing the whole range of green shades produced by mixing these two colors, along its length.

Similar tests made with red and blue, and then with red and yellow, will emphasize to the student’s mind the fact that green is formed from blue and yellow; violet from red and blue; and orange from red and yellow; and that each combination gives an infinite variety of intermediate shades, according to the comparative strength of the individual dyes.

Matching Colors

The next step is to dye some pieces evenly with green, violet, and orange, made by two of the primary colors, and then to try matching these with fresh, newly-mixed baths of the same dyes. It will be found here that success depends upon going slowly; and upon beginning with light shades and building the color up to the desired strength carefully, by means of successive dippings. Note that the color of cloth when wet is much darker than when dry. Some dyers hold the wet cloth to the bright sky and look through it, to get an idea of what the finished color will be like; but positively certain and satisfactory results are arrived at only by wetting the sample to be matched or drying the piece that is being dyed, so that both sample and piece are equally wet or dry, while their color is being compared.

The real difficulty of color dyeing is not met with until the student tries to obtain shades embodying all three of the primary colors. A very few experiments will quickly show that with most modern dyestuffs it is hard to get soft, pleasant tones with the use of only two colors. Natural colors, as we find them in the sky, water, meadow, and woodlands, are never pure; they are invariably mixed. And our eyes are so accustomed to them that shades dyed with simple or pure colors look hard, cold, and inharmonious. Mixtures of two colors are better and softer than single colors, but still rather hard. But when the secondary shade resulting from the combination of two primary colors is mixed with even a small quantity of the third primary color, the result is invariably a soft and pleasing tone.

The above statements presuppose that it is possible, in practice, to obtain good dyestuffs in each class, which are absolutely pure, clean shades of blue, yellow, and red without any admixture whatever. As a matter of fact, while the artificial dyestuffs are much more pure, and hence much more hard and brilliant than the best natural colors, they still in many, if not indeed, in most cases, when carefully studied, show shades that are mixed and not pure. It is very rare to find a blue that does not incline a little to the yellow (a Blue G as it would probably be labelled) or else contain a trace of violet or red (Blue R, or RR). The reds are almost invariably either scarlets, containing a trace of yellow, or crimsons containing blue. And the yellows, also, are very apt to tend towards orange or occasionally show a trace of green.

This, of course, complicates the problem for the practical dyer greatly, and means that instead of being able to cover the whole range of shades with a red, blue, and yellow, it is frequently, if not always, necessary to have some mixed colors, giving sharp, clear shades of violet, green, and orange respectively, to obtain certain effects.

The following diagram will perhaps make this more clear. In this the three primary colors have been divided, each into two shades as indicated by the shade letters, R meaning red, B blue, and G yellow (Germangelb) shades of the colors. By combining these colors as shown in the table, clean, clear shades will be given, whereas other combinations would be likely to spoil the shades.

DIAGRAM OF MIXED COLORS

Red B + Blue R = Violet Blue R + Red B = Violet Yellow R + Red G = Orange

Red B + Orange = Red G Blue R + Green = Blue G Yellow R + Green = Yellow G

Red G + Yellow R = Orange Blue G + Violet = Blue R Yellow B + Orange = Yellow R

Red G + Violet = Red B Blue G + Yellow B = Green Yellow B + Blue G = Green

Take, for example, a special case, namely to turn a piece of crimson calico into a full rich scarlet. The crimson color contains a great deal of red, mixed with a little blue. If the piece were after-dyed, or “topped,” with yellow, even in small quantities, the result would probably be “muddy,” the yellow and blue together being in such strength as to seriously diminish the strength of the red, and make it more or less brown in shade.

If, however, a reddish shade of orange were used for shading, instead of yellow, the red of the mixture would be constantly increased, while the yellow was “killing” the blue, i.e., turning it, with a little red, into grey; and before long the crimson, or bluish shade of red, would turn first into a true but softened red, with neither blue nor yellow predominating, and finally into a scarlet, with distinct traces of yellow.

In making these Three-color Shades, therefore, the component parts of each dyestuff used must be studied; and in every case care must be taken to have the third color, whatever it is, added in such minute quantities as only tosoften and not to spoil the first shade. A teaspoonful, sometimes even a few drops of a solution of one strong color, will generally be enough to soften, and take the edge off, some gallons of dye-liquor containing a hard, clear mixture of the other two. A cupful, on the other hand, or even two or three tablespoonfuls might utterly spoil the bath and turn it into “mud,” as a dyer would say.

It is worth mentioning here that, as a general thing, it is distinctly more interesting to build up shades by dipping first in one bath, and then topping with the second and the third color than it is to mix the different colors to the desired shade first and then dye the material in the single bath. On a small scale there is the same difference, although not so marked and less easily noticed, as that between even dyeing and rainbow dyeing. There is often a loss in regularity and evenness, but the gain in life and light when one color shines through another which covers it more than compensates. This overlaying is not so perceptible in the even dyeing of fine, thin materials, whether yarn or cloth; but with coarse, heavy yarns and thick textiles, effects can be obtained by after-dyeing which cannot be approached when the goods are dyed in one bath.

Matching Shades.—Some people, I believe, go so far as to say that, in order to be really expert at true shade matching when using the three colors in dyeing, a dyer must have begun to learn the art in the person of his grandfather, ninety or a hundred years ago, and kept in practise ever since.

It certainly is true that heredity and early training both have a great deal to do with skill in this art, and a good color dyer will show an almost uncanny instinct, as he instantly picks out differences in shade which an untrained eye would never notice, and without any hesitation prescribes the exact remedy for the defect. Still there are plenty of good, even first-class dyers, nowadays, who have learned their art quite late in life, with the aid of a good eye and intelligent perseverance.

The chief rule to remember is this: Red, blue, and yellow, when mixed in equal strength, make a neutral grey or black. Accordingly any one color will form grey or, as we may say, willneutralize, or becomplementary to a mixture of the other two. Thus red will form grey with green; blue with orange, and yellow with violet. Accordingly if there is too much red in the dye-bath, it can be killed by the addition of a little green; and vice versa. The same is true with the other complementary colors. If this simple rule be kept clearly in mind, most of the problems of matching colors and of getting pleasant and harmonious shades can be worked out easily. It is chiefly a matter of practice, and perseverance.

The student is strongly advised to attack this study in three ways:

First, mix the three primary colors together in one bath, to form definite shades—grey, brown, olive green, steel blue, etc.; then dye the cloth in the bath to see how the colors look when on the materials and dried.

Second, to dye a piece of cloth one mixed shade and by topping with other colors, to alter that shade to match some shade previously selected. For instance, dye a piece a good shade of reddish or copper brown, and then try to “kill” the red in it without materially deepening the shade, i.e., change it from a copper brown to a greyish or dirt brown of about the same depth of color.

Very pretty and instructive experiments can be made along this line of building up soft grey shades, by dyeing the cloth successively in weak baths of the three primary colors. As fast as one color predominates, it can be killed by dipping into successive baths of the other two.

Attractive scarfs and table covers can be made with a little care, by knotting the material and dyeing light rainbow shades of the three colors, one after the other, changing the knots or tied portions after each bath. Properly done, this will produce remarkably interesting, opalescent effects, each color being toned and softened by the other two, although predominating in different parts of the material.

When, in the operation of rainbow dyeing, strongly contrasting colors have been used with unhappy results (such as the red, yellow, and blue tri-color effects that some students will produce) try the effects of toning, or “covering,” as it is often called, with some soft, neutral color which combines in itself all the contrasting tones, or else with a color that is complementary to the most obnoxious one, softening that one and strengthening the weaker shades. Grey, of course, can be used for this; but in general, a soft shade of brown will be found very valuable for taking the edge off of too violent contrasts. The permanganate brown (Manganese bronze), described in the first chapter, can be used with advantage for this purpose.

It is not difficult for a skilful dyer to match any desired shade by using three complementary colors, red, blue, and yellow, provided, of course, that these are pure and unmixed. It often happens, however, that after matching carefully a soft mixed shade by daylight, the colors appear entirely different when viewed by artificial light, and especially by ordinary gaslight. Daylight, as we are accustomed to it, is comparatively evenly balanced in color, is in fact a white light. But artificial light as a rule is distinctly colored, and it is difficult, though now not impossible, to find a light that so closely resembles daylight that colors can be matched at night.

If the light, for instance, has a bluish tinge, like some kinds of electric light, it will kill the corresponding orange in a shade, while yellow light, such as commonly results from the use of oil, candles, or gas (less marked when incandescent mantles are used), dulls and even blackens lavender, violet, and purple shades, while having little or no effect upon yellow, orange, and green.

It is therefore advisable when matching shades that are to be used at night not to use three-color shades wherever that is possible, but to get the desired soft effects by covering directly with grey (i.e., light shades of black) on top of a single or two-color shade.

Chapter V
THE SULPHUR COLORS

Nearly thirty years ago one of the French color houses put on the market a new dyestuff which it named “Cachou de Laval”; Cachou being the same as catechu or “cutch,” the natural brown dyestuff long known and used in the East, and Laval being the name of the town in France where one of its discoverers was born.

This dyestuff was made by heating sawdust, bran, turf, leaves, or other vegetable substances with the strongly reducing alkaline salt,sodium sulphide, in the absence of air. The product, dissolved in water, makes a dark green solution which, after standing in the air a short time, turns brown and deposits a fine brownish powder. Cotton or linen, heated in a fresh solution of this dyestuff, is colored green, but, when wrung out and exposed to air, the green color, which easily washes out, changes into a very permanent, though dull and uninteresting, shade of greyish brown.

This Cachou de Laval was not a success, commercially, because of its poor color. It existed, however, as a chemical curiosity for some twelve or fourteen years; then suddenly, within a few months or even weeks of one another, all the great color houses put out a whole series of colors—chiefly browns, blues, yellows, and blacks—all formed, like this old “Cachou de Laval,” by the action of sodium sulphide or, which amounts to the same thing, of sulphur and caustic alkali, upon organic material, and all capable of dyeing cotton and linen, in one bath, colors extremely fast to washing and generally quite fast to light, after they have been “set” by exposure to the air.

While in general these are known and identified as the Sulphur colors, the different manufacturers have given special class names to their own series thus:

Immedial (Cassella), Katigene (Elberfeld), Kyrogene (Badische), Pyrogene (Klipstein), Thiogene (Metz), Thion (Kalle).

These colors are used almost exclusively for dyeing cotton and linen, when shades fast to washing are required, without first putting them through a mordanting process. The dyeing is done in one bath, with little more difficulty than in the case of the Salt colors described in the last chapter; and, while not faster to light than the best of that class, they are not nearly so liable to bleed.

On wool they are rarely, if ever, used. Wool is almost always dyed with the acid colors in an acid bath; and nowadays the range of these colors is so great and the best of them are so very satisfactory, that there is hardly ever a necessity for using colors of another class.

Neither are these Sulphur colors often used on silk, although methods have been devised for employing them in special cases. All the animal fibres, however, and silk especially, are very easily “tendered,” and indeed destroyed, by heating in an alkaline solution. And so it is very easy to spoil a skein or piece of silk by dyeing it, in the usual manner, with these dyes, dissolved as they must be in the strongly alkaline sodium sulphide.

The presence in the bath of glucose (corn syrup, molasses, etc.), or of glue or gelatine, helps greatly to protect these fibres from the action of the chemicals. But even when dyed with great care, using glucose, and dyeing the goods for but a short time in a bath strong in color but weak in alkali, the results are not very satisfactory, so far as shade and lustre are concerned. They have the advantage, however, of being extremely fast to washing, more so, even, than the Salt colors. In general, however, silk should be dyed with the Acid colors for ordinary work, and with the Salt colors when fastness to washing is required. The Sulphur colors should be reserved for cotton and linen.

On mercerized cotton and artificial silk these dyestuffs take easily and well, when dyed in cold or lukewarm baths. The lustre, however, of the finished goods is apt to be less than when Salt colors or Basic colors are used.