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

Gambir (Uncaria gambir) is a traditional plant from West Sumatera, Indonesia. Containing condensed tannin, gambir could be used as vegetable tanning agent in the leather making process. Sheepskin is usually used as materials for garment leather. Some industries in Indonesia use pickled sheepskin 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 repickle 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.