1. BIOLOGICAL FINISHES

VARIOUS SPECIAL FINISHES APPLIED TO THE GARMENTS:

1. BIOLOGICAL FINISHES: -

1.1 Bio-polishing: -

To produce this effect cellulose enzymes were introduced. The regular acid acting celluloses produced following effects:

• More cutting
• Color loss
• Prone to contour patches
• Bluish heavy effect
• High back staining
• Economical

However, the desire was for enzyme, which was economical as acid cellulose and properties like the neutral acting celluloses. To achieve this, Genetically Modified enzymes were produced, called GMO's (Genetically Modified Organisms). It is known that enzymes have various activities (Endoglucanase I, II; etc.) Exoglucanase, cello-biohydrolase (CBH II) etc. With the advent of genetic engineering it is now possible to increase or suppress one or more of these activities to achieve tailor made results. The effectiveness of the catalytic core (to hydrolyse glycosidic linkages) depends greatly on the absorption by the CBD tail. When tightly bound to the substrate, certain endoglucanases disturb the crystalline structure and induces the various properties like fading, defibrillation, etc. as a result of the mechano-chemical effect. The G-zyme HCL and G-zyme FF series are products designed for good defibrillation but cuts less colour. The less colour loss is due to the fact that the dye is mostly reacted or embedded in the amorphous regions and the G-zyme HCL acts mostly in the crystalline regions.

Enzymes are naturally occurring proteins that are capable of catalyzing specific chemical reactions. Because they only catalyze the reactions and are not consumed, only a small quantity is needed. Cellulase enzymes are proteins that are capable of hydrolyzing (degrading) cellulose. Two kinds of cellulase are currently available: "acid cellulases" which exhibit the most activity in acid pH range of 4.5 to 5.5 and "neutral cellulases" that are active in the 5.5 to 8.0 pH range. Both enzymes are active within an optimal temperature range of about 45°C to 60°C. After the hydrolysis of cellulosic fibers to the desired extent, changing the temperature or pH level can deactivate the enzyme. Because the enzymes are natural proteins, readily biodegradable, they are a favorable alternative to many finishing chemicals and resins that are currently used.

The bio-polishing process targets the removal of the small fiber ends protruding from the yarn surface and thereby reduces the hairiness or fuzz of the fabrics. The hydrolysis action of the enzyme weakens the protruding fibers to the extent that a small physical abrasion force is sufficient to break and remove them. Bio polishing can be accomplished at any time during wet processing but is most convenient performed after bleaching.

It can be done in both continuous or batch processes. However, continuous processes require some incubation time for enzymatic degradation to take place. Removing the fuzz makes the color brighter, the fabric texture more obvious, and reduces pilling. Unfortunately, the treatment also reduces the fabric strength. Smoother yarns also increase the fabric softness, appearance and feel. Since it is an additional process, the bio-polished garments may cost slightly more. Next time you buy apparel, look for the label "Bio-Polished."

1.2 Denim Bleaching: -

Laccases enzymes are used to get outstanding contrast look on denim fabrics. They also eliminate all the negative effects of the indigo dye redeposition at the same time reducing the time of the process necessary to achieve a highly abraded look. Various effects are obtained on denim fabrics using Laccases.