Dyeing in catalase-treated bleaching baths

The conventional rinsing after bleaching to remove the residual hydrogen peroxide, harmful to the dyes either in solution or on the fabric, was replaced by enzymatic cleaning using catalases. The catalasetreated bleaching liquor was reused for dyeing. Though no hydrogen peroxide was detected after the enzymatic process, the bleaching bath composition caused unacceptable colour changes on dyed fabrics. By varying the parameters of the dyeing process – dye, salt, alkali and enzyme concentrations – the colour difference could be reduced significantly and a good dyeing result could be achieved.