Measurement of colour difference in the leather dyeing process with natural dyes

This paper looks into a tanning and dyeing process offering clean technology, which is in the limelight these days as an advanced leather making technology of the future sought by leather industries both at home and abroad. First of all, chrome-tanned leather is treated with two types of tanning agents (Al and Cr) to manufacture wet-blue and wet-white leather. After the tanning process, various colouring matters and the powder-type natural dye were applied to the leather and, on the basis of the Munsell value function, the chromaticity diagram of the colour system and characteristics such as hue, value and chroma were measured. The colour deepened markedly according to the amount of natural dye used, and multiple colours were obtained depending on the mordant in use. The quality of leather was outstanding, test results gave grade 4 or 5 in such categories as colour fastness to rub, wash, heat and light. In addition, the colour was brighter and cleaner on the wet-white non-chrome tanned leather than on the wet-blue.