The goal of this research is to knowing the most optimal in calcification process (liming/scaling) also minimalize the damage been caused by use excessively Na2S. The main material that use is 12 sheet of water snake/buhu snake leather (Hemalopsis Buccata) and 12 sheet of Python leather (Python Reticulatus). Use Na2S with concentration 0,5 oBe ; 0,75 oBe ; 1,0 oBe ; 1,25 oBe for scale removal process. At the end of crust leather tannery process is tested tensile strength and elongation the result compared with SNI number 06-4586-1998 about requirement of quality finished leather from fresh water snake chrom tannin. The concentration treatment Na2S 0,5 oBe optimal influence to the tensile strength and elongation on crust leathers. The lowest tensile strength on buhu snake (Hemalopsis Buccata) is AK1=1551,05 N/cm2 nor lowest crust python leather (Python Reticulatus) is PK3 = 2248,90 N/cm2 the result above minimum 1000 N/cm2 suit with the requirements. The lowest elonagtion buhu snake leather crust (Hemalopsis Buccata) is AK2 = 33,67 % nor lowets python leather crust (Python Reticulatus) is PK2 = 57,09 % the result above maximum 30%. Although incompatibility happened with SNI Number 06-4586-1998 leather processed
(crust, leather glazing and platting) according to tanned standart BASF 2004 is still can be used as leather product because the leather character on a range of requirement.
Keywords: Concentration, tensile strength, elongation, snake leather