Though other primary and secondary colours sometimes result from the application of a single dye, the many thousand different tints can only be produced by the blending of two or more. Moreover, the qualities of the same dye vary greatly, as they depend on the soil where the plant grew, the time of year when it was removed, and the weather and other conditions prevailing during the dyeing.
In nature green is one of the most pleasing colours, but in carpets it is most unsatisfactory, as it has generally a faded appearance, due probably to the fact that one of the dyes of which it is formed by blending is less permanent than the other. The Chinese greens obtained from the buckthorns are generally the best.
Greys and browns are sometimes derived from gall nuts, and reddish brown from henna. For very dark browns and black, iron pyrites has been largely used in both old and modern rugs; but unfortunately the dye has a corrosive effect on the wool, so that the black knots of old rugs are often worn to the warp.
In parts of India flowers of the bastard teak (Butea frondosa) make a favourite dye, from which are produced, by blending with other dyes, a large number of shades ranging from deep yellow to brownish copper tones. Another well known dye is Butti lac, obtained from an insect, Coccus lacca, that lives on the twigs of trees. It is a substitute for cochineal and produces different shades of red, crimson, terra cotta, and purple, according to the other dyes and the mordants with which it is blended.
Besides these few dyes are innumerable others that are used either singly or in combination. Furthermore, different colour effects are produced by the application of different mordants, which it is necessary to use for the reason that without them many fibrous materials are unable to absorb a large number of the dyes. The most valuable of all mordants is alum; and the sulphate of iron and tin are largely employed in the case of red colours. Of the vegetable mordants, pomegranate rind, which contains some yellow colouring matter, is the best known. Valonia also is sometimes used, as well as limes, lemons, the fruit of the tamarind, and the mango.
In the monograph of Mr. Harris on the “Carpet Weaving Industry of Southern India” are a number of directions from an old manuscript owned by a dyer who stated that he was the descendant of twenty generations of dyers who originally came from Tabriz, and that he had made his copy from a Persian book of dyes which had belonged to his grandfather. A few of these are given below, because they show not only the dyes and mordants, but also the methods employed.
“Birbuls Blue. Take cinnabar, indigo, and alum, grind and sift lighter than the light dust of the high hills; soak for ten hours; keep stirring it; put in the wool and soak for many hours. Boil for three hours; wash in kurd water, water in which kurds and whey have been well beaten up; leave for three hours, and then wash and beat again in water.
“A Fine Indigo Blue. Take indigo, soak it in water for twelve hours, grind it to a fine paste in a mortar, add some Terminalia citrina, pomegranate peel, and alum; and mix thoroughly. Boil; put the water into the hot bath and keep stirring till cold. Now mix in some iron-filings water, and boil steadily for another two and a half to three hours; wash with a beating and dry.
“Ruddy Brown Grey. Take sulphate of iron, Terminalia citrina, oak galls, and alum; mix well; dry; then steep for twenty-four hours. Put in the wool; soak it for twenty-four hours, then boil for two or three hours. Dip in a soda-bath, wash, and dry.
“Cinnamon. Take oak galls, acacia bark, cinnabar, and alum, and steep for a night. Put in the wool, and soak for twenty or thirty hours; boil the water for two or three hours and give a soda-bath wash; dip in acidulated water; and wash again with beating.