Cleaner sheep leather tanning process using uncaria gambir: the influence of rebating on leather properties

Black-cube-gambir (pale catechin) is a processed gambir (Uncaria gambier) extract. Containing condensed tannin, black-cube-gambir could be used as a vegetable tanning agent in the leather making process. Some industries in Indonesia use pickled hide/skin as raw material for the next process that the previous bating process is uncontrolled. Therefore, this study aims to determine the effect of rebating in the re-pickle stage on the leather tanned with Uncaria gambir. For alum-gambir tanned leather, rebating increased its softness, tear strength, and hydrothermal stability, while for glutaraldehyde-gambir tanned leather, rebating increased its tensile strength, degree of tannage, and tannin bound. The broad DSC peak revealed that the distribution of collagen molecules of all samples was unequal. Rebating could increase and decrease the quality of leather.