Reduction of natural coloring matter to produce white fabric and must be accomplished with a minimum damage of cotton being bleached.
Objectives of Bleaching
- To impart a pure permanent and basic white effect to the fabric.
- To increase the absorbency of the fabric.
- To produce white finishes
- To make textile material suitable for the subsequent process
Bleaching agent and their classification :
The material by which bleaching is done is called bleaching agent.
There are two types of bleaching agent.
- Oxidizing bleaching agent
- Reducing Bleaching agent
- Oxidizing Bleaching agent : the bleaching agent which fulfills bleaching process by producing unsaturated oxygen is called oxidizing Bleaching Agent
- Reducing Bleaching agent: The bleaching agent which fulfills bleaching process by producing other unsaturated elements rather than oxygen is called reducing bleaching agent.
Some example of two types of bleaching agent
|Oxidizing Bleaching Agent||Reducing Bleaching Agent|
|Hypochlorite (NaOCl) (CaOCl2)||Zinc Dust|
|Bleaching Powder||Stannous Chloride (SnCl2)|
|Hydrogen Peroxide||Sulfur Di.Oxide (SO2)|
|Potassium Dichromate||Ferrous Sulphate (FeSO4)|
|Sodium Chloride (NaCl)||Sodium Hydrosulphate (NaHSO4)|
|Ozone (O3)||Hydrogen Sulphite H2S|
|Potassium Per Manganet K2MnO4|