Abstract

Pretreatment with chitosan formate intensified the depth of shade of C.I. Acid Brown 167 and C.I. Acid Yellow 83 on dyed-through leather; optical microscopy demonstrated that intensification of shade was evenly distributed within the leather which suggests that the large molecular size, cationic polymer penetrated, and was also evenly distributed within, the substrate. Treatment of crusted sheep skin and retanned goat skin crust with chitosan using a two instalment, sandwich dyeing method, enhanced the uptake of C.I. Direct Black 155; the extent of this intensification of shade was similar to that obtained using two commercial, cationic agents. Pretreatment with the polyaminosaccharide imparted a smooth and full character to each leather employed.