Flow Chart of Cotton Whitening Process

The fabric is loaded in a machine & fills with required water.
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Now auxiliary chemicals & acid are added.
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Check the pH (3.4-4.8) of liquor.
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The enzyme is added & run for 30 minutes.
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Check the fabric if enzyme action is proper.
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If not then increase the time.
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Otherwise aquachron for 10 minutes & drain the bath liquor.
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Fill the bath with water.
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Add auxiliary chemicals & raise the temperature of the dye bath.
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Then add caustic soda at 70oC.
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At more temperature add OBA in the bath.
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Raise the temperature to 110oC.& run for 40 minutes.
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Then lower the temperature to 80oC. & check the shade.
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By aquathlon lower the temperature to 60oC..
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Add acid to neutralize & run for 10 minutes.
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At last aquachron& drain the bath liquor

All-natural fibres including cotton have some natural colouring matter. Which confers a yellowish-brown colour to the fibre. The purpose of bleaching is to remove this colouring material and to confer a white appearance to the fibre.

Moreover, to an increase in whiteness, bleaching results in an increase in absorbency, levelness of pre-treatment, and complete removal of seed husks and trash. In the case of the production of full white finished materials, the degree of whiteness is the main requirement of bleaching. The amount of residual soil is also taken into consideration. Because of the possibility of later yellowing of the material. In the case of pretreatment for dyeing, the degree of whiteness is not as important as. For example, the cleanliness of the material, especially metal content.