Enzyme Washing

In enzyme washing, cellulase enzymes are used. Hydrolysis of the cellulose, which is catalysed by cellulase, causes the surface fibres to become weakened and later they get removed when there is either fabric-to-fabric abrasion or fabric-to-stone abrasion during washing. The temperature and the pH used are specific to the type of cellulase employed. Usually neutral cellulases are applied at pH 6–7, while acid cellulases are applied at pH 4.5–5.5. However, the latter result in a greater extent of back staining, being more penetrative. An enzyme dose of 2–4 g/L is normally enough, provided that the enzyme activity is not impaired. In general, the colour of the enzyme washed goods is more uniform, particularly when stone is not added. Because cellulases are reactive only on cellulose, any size materials or other impurities must be removed before the cellulase treatment.