Abstract

Alkali and neutral salt treatment, especially in liming is a key procedure in order to achieve a good quality of leather. However, liming creates sludge and wastewater which are difficult to process. To find a clean replacement for lime we need to know the properties of skin after alkali and neutral salt treatment. Collagen fibre and cattle hide are treated in alkali-neutral salt solutions. Collagen fibre will be swelled in alkali solutions in its axial direction. Sodium sulphate in high concentration depresses collagen fibre’s swelling rate in alkali solutions, but sodium chloride does not have this effect. Hydrolyzates in alkali and neutral salt solutions are composed mostly of degraded collagen, having lost its characteristic collagen triple-helical conformation. Neutral salt may inhibit the cleavage of the salt bridges of collagen fibre in alkali solutions which will enhance its physical properties such as tensile strength.