PIGMENT PRINTING AND DYEING OF COTTON

Both organic and inorganic pigments come into consideration for the dyeing of cotton. Organic pigments are of great importance in textile printing. An estimated 45% of all textile prints are produced in this manner, because it is the simplest and cheapest method available. They are printed together with a suitable binder and fixed by exposure to hot air at temperatures above 120 degree C with the resultant prints meeting current market requirements. Cotton and its blends with synthetic-polymer fibers such as polyester are most suitable for printing. The use of inorganic pigments, or mineral pigments as they are more commonly known, is confined to dyeing cotton in woven fabrics. The process differs fundamentally from the application of organic pigments since for example, the mineral pigments iron or chromium hydroxides or mixtures thereof are produced on and within the fiber. The fabric is padded with caustic soda and washed-off followed by a final dryng. Very cheap dyeings, mainly khaki and olive green, of very good fastness to light and weathering are obtained.