This art consists in dyeing cloth with certain colors and figures upon a ground of a different hue, the colors, when they will not take hold of cloth readily, being fixed to them by means of mordants, as a preparation of alum, made by dissolving 3 lbs. of alum and 1 lb. of acetate of lead in 8 lbs. of warm water. There are added at the same time 2 oz. of potash, and 2 oz. of chalk.
Acetate of iron, also, is a mordant in frequent use in the printing of calicoes, but the simple mixture of alum and acetate of lead is found to answer best as a mordant.
_To Apply the Mordants._
The mordants are applied to the cloth, either with a pencil or by means of blocks, or rollers, on which the pattern, according to which the cotton is to be printed, is cut. As they are applied only to particular parts of the cloth, care must be taken that none of them spread to the part of the cloth which is to be left white, and that they do not interfere with each other when several are applied; it is necessary, therefore, that the mordants should be of such a degree of consistence, that they will not spread beyond those parts of the cloth on which they are applied. This is done by thickening them with flour or starch, when they are to be applied by the block, and with gum arabic when they are to be put on with the pencil. The thickening should never be greater than is sufficient to prevent the spreading of the mordants; when carried too far, the cotton is apt not to be sufficiently saturated with the mordants, and of course the dye takes but imperfectly.
In order that the parts of the cloth impregnated with mordants may be distinguished by their color, it is usual to tinge the mordants with some coloring matter. The printers commonly use the decoction of Brazil-wood for this purpose.
Sometimes, the two mordants are mixed together in different proportions, and sometimes one or both is mixed with an infusion of sumach, or of nut-galls. By these contrivances a great variety of colors are produced by the same dye-stuff.
_Process of Dyeing, etc._
After the mordants have been applied, the cloth must be completely dried. It is proper for this purpose to employ heat, which will contribute towards the separation of the acetic acid from its base, and towards its evaporation; by which means the mordant will combine in a greater proportion and more intimately with the cloth.
When the cloth is sufficiently dried, it is to be washed with warm water and cow-dung, till the flour or gum employed to thicken the mordants, and all those parts of the mordants which are uncombined with the cloth, are removed. After this the cloth is to be thoroughly rinsed in clean water.
Almost the only dye-stuffs employed by calico printers are indigo, madder, quercitron bark, or weld, and coal-tar colors; but weld is little used, except for delicate greenish yellows. The quercitron bark gives colors equally good; and is much cheaper and more convenient, not requiring so great a heat to fix it. Indigo, not requiring any mordant, is commonly applied at once, either by a block or by a pencil. It is prepared by boiling together indigo and potash, made caustic by quicklime and orpiment; the solution is afterwards thickened with gum. It must be carefully excluded from the air, otherwise the indigo would soon be regenerated, which would render the solution useless. dr. Bancroft has proposed to substitute coarse brown sugar for orpiment; it is equally efficacious in decomposing the indigo, and rendering it soluble, while it likewise serves all the purposes of gum. Some calicoes are only printed of one color, others have two, and others three or more, even to the number of 8, 10, or 12. The smaller the number of colors, the fewer in general are the processes.
_New Process to Separate the Red Coloring Principle of Madder._
For this purpose 3 tubs are necessary, say, A, B. C. The first, or A, sufficient for 55 lbs. of madder, is to be 2 feet 8 inches deep, and 2 feet 6 in diameter. The second, or B. is 5 1/2 feet high and 3 feet in diameter. This tub is to be furnished with 3 cocks, the first placed at 2, the second at 3, and the third at 4 feet above its bottom. A serves as a fermenting tub; B, a washing vessel; and C as a deposit. These tubs are placed near to each other, in the summer, in the open air, under a shed; in the winter, in a cellar kept at from 66 to 70. To commence the process, put from 50 to 55 lbs. of ground madder into A, and add water stirring the mixture continually, until the madder, when at rest, is covered with an inch and a half of water. In 36 or 48 hours (being at rest) fermentation takes place and raises a crust of madder to the surface. The mass is now to be transferred to the second tub or B. which is then to be filled with water, where it is to repose for 2 hours. The uppermost cock is then opened, next the under one, and lastly the third. The liquor collected from the second and third cocks is carried to the tub C, where the precipitation of the madder that escaped from B. is completed. You may make repeated washings of the madder in B. until the water ceases to be colored. Care should be taken in summer to prevent the madder from fermenting a second time. The madder in C being washed and precipitated, is equally good with the other.
_To Print Yellow._
For yellow, the block is besmeared with acetate of alumina. The cloth, after receiving this mordant, is dyed with quercitron bark, and is then bleached.
One of the most common colors on cotton prints is a kind of Nankeen yellow, of various shades down to a yellowish brown or drab. It is usually in stripes or spots. To produce it, the printers besmear the block, cut out into the figure of the print, with acetate of iron, thickened with gum or flour; and apply it to the cotton, which, after being dried and cleansed in the usual manner, is plunged into a potash lye. The quantity of acetate of iron is always proportioned to the depth of the shade.
Red is communicated by the same process, only madder is substituted for the bark.
The fine light blues which appear so frequently on printed cottons, are produced by applying to the cloth a block besmeared with a composition consisting partly of wax, which covers all those parts of the cloth which remain white. The cloth is then dyed in a cold indigo vat, and after it is dry, the wax composition is removed by hot water.
_Lilac and Brown._
Lilac, flea brown, and blackish brown, are given by means of acetate of iron, the quantity of which is always proportioned to the depth of the shade. For very deep colors a little sumach is added. The cotton is afterwards dyed in the usual manner with madder and then bleached
To 12 qts. of muriatic acid, add by degrees 1 qt. of nitric acid, saturate the whole with grain tin and boil it in a proper vessel till two-thirds are evaporated.
To prepare the indigo for mixing with the solution, take 9 lbs. of indigo, 1/2 pound of orange orpiment, and grind it in about 4 qts. of water; mix it well with the indigo, and grind it all in the usual way.
_To Mix the Solution of Tin with Prepared Indigo._
Take 2 galls. of the indigo prepared as above; then stir into it, by degrees, 1 gall. of the solution of tin, neutralized by as much caustic alkali as can be added without precipitating the tin from the acids. For a lighter shade of green, less indigo will be necessary. The goods are to be dipped in the way of dipping China blues; they must not however, be allowed to drain, but moved from one vat to another as quickly as possible. They are to be cleansed in the usual way, in a sour vat of about 150 galls. of water to 1 gall. of sulphuric acid, they are then to be well washed in decoctions of weld, and other yellow color drugs, and are to be branned or bleached till they become white in those parts which are required colorless.
_To Print Dove color and Drab._
Dove-color and drab are given by acetate of iron and quercitron bark; the cloth is afterwards prepared in the usual manner.
_To Print different Colors._
When different colors are to appear in the same print, a greater number of operations is necessary. Two or more blocks or rollers are employed; upon each of which, that part of the print only is cut which is to be of some particular color. These are besmeared with different mordants and applied to the cloth, which is afterwards dyed as usual. Let us suppose, for instance, that these blocks are applied to cotton, one with acetate of alumina, another with acetate of iron, a third with a mixture of those two mordants, and that the cotton is then dyed with quercitron bark and bleached. The parts impregnated with the mordants would have the following colors:
Acetate of alumina, yellow; acetate of iron, olive, drab, dove. The mixture, olive green, olive.
If the part of the yellow is covered over with the indigo liquor applied with a pencil it will be converted into green. By the same liquid, blue may be given to such parts of the print as require it.
If the cotton is dyed with madder, instead of quercitron bark, the print will exhibit the following colors:
Acetate of alumina, red: acetate of iron, brown, black. The mixture, purple.
When a greater number of colors is to appear--for instance, when those communicated by bark, and those by madder are wanted at the same time - mordants for parts of the pattern are to be applied. The cotton then is to be dyed in the madder bath and bleached; then the rest of the mordants to fill up the pattern, are added, and the cloth is again dyed with quercitron-bark, and bleached. The second dyeing does not much affect the madder colors, because the mordants, which render them permanent, are already satu rated. The yellow tinge is easily removed by the subsequent bleaching. Sometimes a new mordant is also applied to some of the madder colors; in consequence of which, they receive a new permanent color from the bark. After the last bleaching, new colors may be added by means of the indigo liquor. The following table will give an idea of the colors which may be given to cotton by these processes.
I. Madder dye.--Acetate of alumina, red; acetate of iron, brown, black; acetate diluted, lilac. Both mixed, purple.
II. Black dye.--Acetate of alumina, yellow; acetate of iron, dove, drab; lilac and acetate of alumina, olive; red and acetate of alumina, orange.
III. Indigo dye.--Indigo blue; indigo and yellow, green.
_To Print in Coal-tar Colors._
The colors are mixed with albumen printed on the fibre; the albumen is then coagulated, and the color thus fixed. Another method consists in printing with tannin on the fabric, previously impregnated with stannate of soda, and then dyeing with a hot, dilute, acid bath. The color on the unmordanted parts, is easily discharged. This preparation is not necessary for silk and wool.
_To Print Green with Aniline._
Print the design with a thickened solution of chlorate of potassa; pass through a solution of an aniline salt, in 2 or 3 days the green color will be developed. It may be changed to dark blue by the use of soap or an alkaline liquid. Another method is to use alternately aniline blue and picric acid.
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