Bio Polishing Enzymes

Cotton and other natural and man-made cellulosic fibres can be improved by an enzymatic treatment called Bio-Polishing. The main advantage of Bio-Polishing is the prevention of pilling. Cellulases hydrolyse the microfibrils (hairs or fuzz) protruding from the surface of yarn because they are most susceptible to enzymatic attack. This weakens the microfibrils, which tend to break off from the main body of the fibre and leave a smoother yarn surface. A ball of fuzz is called a 'pill' in the textile trade. These pills can present a serious quality problem since they result in an unattractive, knotty fabric appearance. After Bio-Polishing, the fabric shows a much lower pilling tendency. Other benefits of removing fuzz are a softer, smoother feel and superior colour brightness. Unlike conventional softeners, which tend to be washed out and often result in a greasy feel, the softness-enhancing effects of Bio-Polishing are washproof and non-greasy. AETL's Sebrite series is much effective to impart pill proof biopolishing on woven and knit cotton fabric and garments. Sebrite also gives high color retention.

For cotton fabrics, the use of Bio-Polishing is optional for upgrading the fabric. However, Bio-Polishing is almost essential for the new polynosic fibre lyocell (the leading make is known by the trade name Tencel®). Lyocell is made from wood pulp and is characterised by a tendency to fibrillate easily when wet. In simple terms, fibrils on the surface of the fibre peel up. If they are not removed, finished garments made with lyocell will end up covered in pills. This is the reason why lyocell fabric is treated with cellulases during finishing. Cellulases also enhance the attractive, silky appearance of lyocell. Lyocell was invented in 1991 by Courtaulds Fibres (now Acordis, part of Akzo Nobel) and at the time was the first new man-made fibre for 30 years. Addcool series is best suitable for biopolishing of lyocell as it works at pH 5.5 - 6.0 and temperature 30 - 45 °C, causing less damage to fabric and high quality finish.

The Bio-Polishing of cotton and other fibres based on cellulose came first, but in 1995 enzymes were also introduced for the Bio-Polishing of wool. Wool is made of protein and so this treatment features a protease that modifies the wool fibres. 'Facing up' is the trade term for the ruffling up of the surface of wool garments by abrasive action during dyeing. Enzymatic treatment reduces facing up, which significantly improves the pilling performance of garments and increases softness. Proteases or Sebrite WDE of AETL are also used to treat silk. Threads of raw silk must be degummed to remove sericin, a proteinaceous substance that covers the silk fibre. Traditionally, degumming is performed in an alkaline solution containing soap. This is a harsh treatment because the fibre itself, the fibrin, is also attacked. However, the use of proteolytic enzymes is a better method because they remove the sericin without attacking the fibrin. Tests with high concentrations of enzymes show that there is no fibre damage and the silk threads are stronger than with traditional treatments.