PENGARUH PENGGUNAAN TAWAS DALAM PEWARNAAN ALAMI EKSTRAK KULIT BUAH NAGA (Hylocereus polyrhizus) PADA KULIT SAPI SAMAK NABATI TERHADAP KETAHANAN BENGKUK DAN KETAHANAN GOSOK KERING

The intention of this research was to determine the effect of concentration of alum in natural color of dragon fruit peel extract on swelling resistance and dry rubbing resistance of vegetable tanned cow skin and to find out the best alum concentration in natural coloring of dragon fruit skin to increase swelling resistance and dry rubresistance on vegetable tanned cow skn. The material are used in this research is a vegetable tanned leather pick up at tanned leather craftmen in Yogyakarta. The research uses an experiement method. The experiment used was as a Completely Randomized Design (CRD). The experiment give in this research were as follows.: P0 = Wtihout not give alum P1 = Giving alum 20 grams, P2 = Give alum 30 grams, P3 = Give alum 40 grams, P4 = Giving alum, every treatments are repeated at three times. There also parameters measured including swelling resistance and dry resistance. The result of this research indicate that the concentration of alum use as a dye binder in the natural coloring of dragon fruit skin extract on vegetable tanned cow skin had a real influence (P < 0.05)on swelling resistance and dry rub resistance. The deduction use of the alum as a fixator in the natural coloring of dragon fruit peel extract on vegetable tanned cow leather can fix the resistance of swelling and dry rubbing resistance and concentration of the best alum as a fixator of natural dyes as much as 50 grams/liter and provide a 5 (not cracked)and dry rub resistance with a value of 5 (does not obscure)