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Calico Printing (This art consists in dyeing)

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 dyestuff. 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.

Dye-stuffs.

Almost the only dye-stuffs employed by calicoprinters 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 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 60° 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 trans. ferred 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