Bleaching Machinery for Optical Whiteness
topic
Bleaching machines treat scoured fabric with hydrogen peroxide at 0.5 to 3 grams per litre stabilised by sodium silicate or organic stabilisers at pH 10 to 11 in J-boxes or steamers at 90 to 100 degrees Celsius for 30 to 60 minutes, destroying the natural colouring matter of cotton to achieve whiteness index above 75 ISO, followed by peroxide-killing enzymatic or reducing agent treatment and thorough washing before optical brightening agent addition.
Role
Achieves the optical whiteness required for white goods and the colour depth potential for pale and pastel shades in dyed fabrics by destroying the natural pigments in cotton and regenerated cellulosic fibres that would otherwise produce a cream background detectable in pale dyeings, with bleaching quality being critical for achieving the bright, true colours in pastel and white product ranges that premium customers demand.