History of Technology in India, Vol. I: From Antiquity to c. 1200 A.D. v1.c20.7

v1.c20.7

Dyes which are prepared in the form of powder, paste or solution are utilized generally in colouring cotton, wool, silk, cloth of natural fibres, in cosmetics, in the manufacture of ink etc. Many soluble dyes are converted into pigments by forming insoluble salts (by replacing sodium in a dye salt with calcium) for use in lacquers, paints, etc (McGraw-Hill). Dyestuffs are used for artificial colouring of food articles and soft drinks. They are also used for colouring hair, fur, metals, etc.