Definition of Bleaching
Bleaching of cotton
- Boiling with alkali.
- Bleaching the organic matters by some bleaching agents.
- Souring treatment with dilute H2SO4 or HCl.
- Steeping in warm solution of soda for some hours.
- Bleaching powder treatment or sodium hypochlorite.
- Souring with dilute acids.
- Washing free of acids.
- Boiling in alkaline lye. This is carried out in kier-boil (6 to 8 hours) in alkaline lye (3% soda ash or 2% caustic soda on weight of cotton).
- Bleaching powder solution 2% Tw treatment contained in stone cistern which is provided with a false bottom.
- Souring with dilute acids HCl about 2% Tw.
- Washing to remove traces of acids.
- Optical bluing.