Extraction and Optimization of Natural Dye from Hambo Hambo (Cassia singueana) Plant Used for Coloration of Tanned Leather Materials

Abstract

This investigation was aimed at introducing natural dye extracted from the bark of Cassia Singueana plant for dyeing chrome tanned sheep skin crust leather. The colorant was extracted by aqueous extraction and its strength evaluated using UV-Visible spectroscopy. The extraction with the highest strength (3.9 at λmax of 400 nm) was obtained at temperature of 95°C, concentration of 60 g/l, and time of 60 minutes. The possibility of using aloe vera juice and mango bark extract as natural mordants for leather coloration was investigated. Dyeing was conducted with and without mordant using different combinations of temperature, time, pH, and concentration of mordants. All three mordanting techniques were evaluated. The color strength (K/S), CIE L∗a∗b∗ values, and fastness properties (light, rubbing, and perspiration) of dyed leather samples were evaluated using appropriate instruments and according to international standards. Majority of samples exhibited that fastness result was in the range of good-excellent. Significantly better color fastness was obtained in case of leather samples premordanted with aloe vera. This study leads to the conclusion that dye extracted from bark of Cassia singueana can be used as colorant for tanned leather with the selected natural mordants.