Wednesday, 6 February 2013

Some Notes about Bleaching

Effect of Metals on Hypochlorite Bleaching

Copper and Iron catalyze the oxidaton of cellulose by Sodium hypochlorite degrading the fiber. Fabric must be free from rust spots and traces of metals otherwise bleaching will damage the fabric. 

Stainless stell equipments should be used and care must be taken that the water supply is free from metal and rust from pipes. Prescouring from chelating agents become an important step when bleaching with sodium hypochlorite. 

Weight Loss of Fabric in Bleaching

After bleaching operation the weight loss in the material takes place and it depends on different types of bleaching agents that are used. Due to the removal of coloring matters and fiber damage in the bleaching, textile material may lose considerable weight. In a study it was found that in plain weave fabrics, the weight loss was upto 11% for Sodium hypochlorite bleach and upto 8% in Hydrogen Peroxide bleach.





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