Application of Lac Dye in Shoe Upper Leather Dyeing

Shoe upper leather samples were dyed with the natural lac dyes (byproduct of shellac and shellac products industry) extracted from washings of the stick lac by conventional methods. The aim of this research is to utilize this dye water and reveal the novel natural recipe for eco-friendly dyeing operation of shoe upper leather processing. The extraction of lac dye was carried out by using water at different temperatures. The lac dye was applied on the leather samples with and without using mordants; and three different mordants (CuSO4, FeSO4, [KAl(SO4)2]) were used following metamordanting method of dyeing. Absorbance and λmax of all dye liquors at different time intervals were determined by UV-visible spectrophotometer. The dyestuffs exhaustion and uptake were investigated and results showed that mordanted dyeing increased the dye uptake on leather than unmordanted dyeing. The FTIR analyses samples were carried out and it was found that lac dye could be mainly composed of -OH, -NH, >C=CC=O, -COOH functional groups. The fastness properties such as fastness to washing, rubbing (dry and wet) and light of prepared leather samples were assessed. The results of color fastness of the mordanted and unmordanted leather samples showed excellent (5) and best (4-5) gray scale rating respectively.