The New Student's Reference Work/Bleaching

Bleaching (from the Anglo-Saxon blaec, pale), the process of whitening textile fabrics (cotton, linen and silk, also wool) by removing coloring matters and substances naturally present, or adhering to them in the course of their manufacture. In early days it used to be the custom to send Scotch linens to be bleached in Holland, and the latter name is still used for a kind of unbleached linen. The term lawn, which continues in use, received its name from being spread on lawns or cultivated grass fields for bleaching purposes. Besides linen and cotton, wool, silk, jute, paper and now even wood are submitted to the bleaching process. The term bleaching is moreover applied to the decolorizing of castor-oil, bees-wax and other fatty materials by exposure to sunlight. Scouring and bleaching are now largely effected by the use of chemicals and volatile liquids, soda ash, resin soaps and more or less caustic alkalis being utilized in place of baths of lime, lye and sulphuric acid. For the bleaching of silk, after scouring, sulphur dioxide is used, or, better still, hydrogen peroxide. As a bleaching agent, chloride of lime or bleaching powder is resorted to for the removal of metallic and other colors in calico-printing.