Abstract

A novel wet-white tanning approach based on combination tanning with tannic acid (TA) and Laponite nanoclay has been proposed. Thermal stability measurements show that the introduction of Laponite nanoclay gives an obvious increase in the shrinkage temperature (Ts) of TA-tanned leather, implying the presence of the synergistic effect between TA and Laponite nanoclay in the combination tanning process. The optimized tanning system, i.e. 20% TA combination tanned with 3% Laponite in onebath for 3 hours at 25°C and final pH~3.5, confers wet-white leathers with Ts above 89°C, and good storage stability. The introduction of Laponite nanoclay facilitates the fixation of TA in the wet-white leather. Scanning electron microscopic (SEM) results show that the combination tanned leathers exhibit fine isolated collagen fibre networks in comparison with that of solo TA and solo Laponitetanned leather. The presence of Laponite nanoclay not only improves the mechanical strength of the resulting leather, but also gives an ultraviolet protection property.