Bleach

The bleaching of textiles appears to have been known as early as 300 B.C. when soda ash was prepared from burned seaweed and used to clean cloth. Then the cloth was treated with soured milk to reduce its alkalinity. The bleaching process was completed when the cloth was exposed to the Sun. This type of sun bleaching typically took several weeks.

A Swedish chemist discovered chlorine gas in 1784 and succeeded in demonstrating its use for decolorizing vegetable dyes. Fifteen years later a patent was awarded for a bleaching powder formed by the absorption of chlorine gas into dry hydrate of lime. Following World War I the technology for shipping liquid chlorine was developed. This allowed for on-site production of sodium hypochlorite in textile mills and led to the development of other chlorine-based bleaches. In 1928, the first dry calcium hypochlorite bleach containing 70% available chlorine was produced in the United States. This material largely replaced bleaching powder in commercial bleaching.

Hydrogen peroxide was prepared as early as 1818 but did not find use in the bleaching of textiles until much later. By 1930, the prices of peroxides had dropped sufficiently to allow the use of hydrogen peroxide in the bleaching of cotton, wool, and silk. By 1940, 65% of all cotton bleaching was done with hydrogen peroxide.