Effect of Acid Swelling and Its Impact on the Properties of Cow Industrial Glove Leathers

The development of commercially successful salt-free chrome tanning technology is the need of global leather sector to reduce the total dissolved solids in wastewater. Though some attempts have been made to develop salt-free chrome tanning technology, drawbacks such as slow diffusion of chromium, unevenness in softness and other organoleptic properties are the major concern. The generation of localized acid swelling might be a reason for the above drawbacks and no scientific literature available for the same. Hence, it is important to analyze the effect of acid swelling and its impact on the diffusion of chromium, ageing characteristics of wet-blue leather and physical properties of crust leather. The results show that the acid swelling delays the diffusion of chromium in tanning process and also enhances the growth marks on wet-blue leather. The ageing study reveals that the wet-blue obtained from acid swollen system dehydrates faster than the conventional salt based chromium tanning system. In addition, the wet-blue leather from acid swollen system is prone to fungal attack. The industrial glove leather obtained from acid swollen system has reduced strength characteristics viz., 15% reduction in tensile strength, 17% reduction in tear strength and 20% reduction in grain crack/bursting strength. Further, the degree of heterogeneity in softness is high for crust leather obtained from acid swollen system and also more looseness with internal emptiness. Color value measurements reveal that the crust leather obtained from the conventional tanning system is lighter in shade than the acid-swollen system. The results will be useful to design commercially viable salt-free or low-salt tanning systems as well as to tackle the inadvertent industrial scenario where the tanners are looking for solutions for accidental acid swelling and subsequent salvage of the leathers for possible recovery and applications.