Abstract

The main aim of this work was to assess the homogeneity of S.L.T.C. Standard Hide Powder and to show the extent of batch differences. Four batches were examined and compared with laboratory prepared hide powder and with limed pelt delimed to the same extent as hide powder. The assessment methods used were chemical, physical, and histological, and included shrinkage temperature determination and differential thermal analysis. The hide powders were sieved into five fractions. Shrinkage temperature differences were found between the Standard and laboratory samples for the finest fractions, with those of the Standard Hide Powder being lower. The coarsest fraction of Standard Hide Powders contains two types of fragments, fibrous and horny, the latter appearing to have suffered heat damage. Histochemical examination and differential thermal analysis confirmed the presence of some damaged collagen in Standard Hide Powder, presumably caused by grinding.

Standard Hide Powder is produced for tannin analysis. The different fractions of hide powder gave surprisingly consistent results in the analysis of a tanning extract, except for the coarsest fraction, which led to a tannin content about 3% lower. The availability of Standard Hide Powder makes it a convenient substrate for experimental work. In dyeing studies, it gave results less consistent than those obtained with laboratory prepared samples. The presence of the grain layer could be the reason for the inconsistencies, but this does not seem to be the case, since laboratory prepared grain hide powder gave dyeing results very similar to those from hide powder almost free from grain. When using Standard Hide Powder for purposes other than tannin analysis, it is advisable to reconsider its suitability for each specific case.