Dyeing. The art of coloring fabrics by immersion in a properly prepared bath. The matters used for dyeing are obtained from vegetables, animals and minerals, and the subjects to which they are applied are porous materials in general, but especially wool, cotton, silk, linen, fur and feathers. The great diversity of colors obtained in dyeing is the result of the combination of two or more simple coloring substances with one another, or with certain chemical re-agents. To render the colors permanent, the subsequent application of a mordant, or the precipitation of the coloring matter by the direct use of a mordant, is usually required; but when aniline and some other artificial dyes are used no mordant is necessary. The superficial application of pigments to fabrics, as in painting or as in cheap processes of calico printing, does not constitute dyeing, because the dyes so applied do not penetrate the fiber, and are not intimately incorporated with it. The most important dyestuffs are cochineal, madder, indigo, logwood, fustic, and the various preparations from aniline.

That dyeing was practiced in the most ancient times is abundantly proven by the frequent mention of dyed colors in the oldest extant writings; that it was not a common art seems apparent from the uses to which colored garments were devoted, and the high distinction which they conferred upon the wearers. The bright colors, "blue, purple and scarlet," mentioned in the book of Exodus, as well as the "Tyrian purple" so often referred to by Roman writers, were so costly as not to be available for general and common use. From the perishable nature of textile fabrics and their comparatively small intrinsic value, very few ancient examples of the dyer's art have been preserved. There is, however, one account of cloth containing dyed yarn which may have been in the dyer's hands in Egypt 1,000 years before the Christian era; and there is still in good preservation ecclesiastical garments containing dyed silks which are certainly 600 to 700 years old. Some of the mummy cloths taken from the Pyramids have a border of blue and fawn color made by colored threads introduced in the loom. At the Centennial Exposition in 1876 there was in the Peruvian Department a piece of woven cloth taken from the tomb of the Incas at least 2,000 years old, and in an excellent state of preservation, with the colors scarcely dimmed through a cycle of many centuries. Stuffs dyed with purple were one of the most considerable branches of the commerce of the ancients. The purple disputed value with gold itself in those remote times, and was the distinguishing mark of the greatest dignities of the universe. This sort of dyeing now constitutes one of the lost arts. The earliest account of the processes and materials used by dyers is found in a French collection of manuscripts written in 1410, and the earliest printed account of dyeing processes occurs in an Italian work published in 1510. In this work mention is made of woad and methods of making indigo from it; of indigo imported from India, called bagadel; of sumac, gall nuts, and the berries of buckthorn, to be used for yellow; and of sandal wood and madder for red. It is very clear from these works, and from numerous existing samples of colored fabrics, that dyeing was well understood in Europe in the fifteenth century, and that the materials at the command of the dyer were sufficiently numerous and varied to enable him to produce all desired shades of color. The discovery of America was soon followed by the introduction of cochineal. Logwood or campeachy was also an introduction from the New World, and greatly enlarged the power of the dyer, though from the looseness of the colors it yielded it brought his art into some disrepute, but eventually settled down as the principal ingredient in the common black dye. In 1810 quercitron bark was discovered in America and introduced for dyeing yellows, which has from its superior richness, and less cost, displaced all other materials used for that purpose. Of the natural dyes introduced in the present century probably the most important is catechu. The discovery of the use of bichromate of potash as a mordant for woolen goods belongs to the latter half of this century, and has been of the highest benefit to the dyer.

In the year 1858 commenced the discovery and application of a series of artificial coloring matters, which have created a distinct era in the history of dyeing. Up to that date the coloring matters used in dyeing were either the spontaneous productions of nature or simple preparations of the same. In this year was produced a dyeing material from aniline. Other discoveries rapidly followed, and in the course of a few years it may be said that a hundred patents were taken out for methods of making artificial coloring matters from aniline and its preparations; these alkaloid bases, under the transforming hands of chemists, supplied the dyer with every shade and hue which could be desired. Imitating more or less closely the colors obtained from natural coloring matters, they have no similarity of chemical composition, but are in every respect fundamentally different from them. In 1870 a German chemist by means of chemical investigation succeeded in transforming an extract of aniline into alizarin, the latter being identical in chemical composition as well as tinctorial properties with the coloring matter of madder, one of the most anciently known and most valuable of all natural dye-stuffs. This was the first instance in which chemistry had produced one of the old and well-known colors of the dyer; in a short time after its discovery it was made practically available for the trade, and has at this date (1892) almost entirely driven from the market the native product - accomplishing a revolution which has no parallel in the history of coloring matters. [See Aniline, Alizarin, Woad, Mauve, Madder, Logwood, Pigments, Indigo, Mordant, Purple, Turkey Red, Cochineal, Colors, Calico Printing].