Textiles and leather

Tata Chemicals is a major supplier of soda ash and sodium bicarbonate to the textile and leather industries.

Soda ash
TCL's light soda ash is used in dyeing cotton and other cellulose fibres such as linen, rayon, tencel or hemp, to increase the pH (alkalinity) of the reaction. The ideal pH depends on the fibre and the individual dye colour. Soda ash changes the pH of the fibre-reactive dye and cellulose fibre so that the dye reacts with the fibre, making a permanent attachment that holds the dye to the fibre.

Sodium bicarbonate
Sodium bicarbonate (technical and refined grades) is used in curing wool and silk fibre. It also aids in the dyeing and printing of wool and silk fabrics. Textile professionals regard the quality of sodium bicarbonate manufactured by TCL to be ideal for their dyeing and printing needs.

Sodium bicarbonate is also used for tanning in the leather industry. Tanning helps preserve animal hides or skins, makes them immune to bacterial attack, raises the shrinkage temperature and prevents the collagen fibres from sticking together on drying. When treated with sodium bicarbonate, leather remains porous, soft and flexible.

Sodium bicarbonate is also commonly used as a pH controller in basic leather tanning. The active constituent in tanning chemicals is tannic acid. Tanning is a time-consuming and exacting process, requiring careful control of factors such as pH, temperature, humidity and concentration.

TCL's sodium bicarbonate increases the alkalinity of chromium sulphate solutions to assist the cross-linking of chrome complexes with the animal-hide collagen of leather. The reaction stabilises the animal-hide collagen fibres so that they are no longer biodegradable.