Burial-Induced Deterioration in Leather – A FTIR-ATR, DSC, TG/DTG, MHT and SEM study

Abstract

In this study we used an analytical approach based on complementary techniques that targets all structural levels of collagen to investigate the effects of burrial tests on vegetable-tanned lather. For the first time, a group of deterioration markers specific to molecular, fibrillar and and fibrous structure of collagen in leather was associated with the anaerobic condition of burried leather. Gelatin was identified both through the FTIR-ATR spectral markers (molecular alteration of collageneous triple helix structure) and SEM imaging (alteration of fibrils and fibres morphology). Loosening of collagen-tannin interaction and de-tanning were detected by the application of second derivative spectral analysis. Collagen denaturing profile was evidenced by DSC analysis and documented by SEM observations at high magnification, while TG/DTG analysis gave information on the leather thermo-oxidative deterioration. Our results confirmed that the shrinkage temperature measured by MHT method could be misleading. However, this method proved its usefulness in assessing the structural inhomogeneity of collagen in buried leather and identifying gelatin. The complementary FTIR-ATR, DSC, TG/DTG, MHT and SEM analytical protocol proved its high effectiveness and could thus be extended to the challenging study of archaeological leather.