The influence of the soil aging exerting on the stability of proteinaceous binders in Chinese polychromy artworks

Abstract

Soil aging was the major aging form that affected great numbers of unearthed Chinese ancient artworks and would fundamentally influence the deterioration processes of the proteinaceous binders applied in polychromy artworks. The three main categories of the proteinaceous binders, pig glue, egg and milk, would present various stabilities towards soil aging due to their different characteristics, the study of which was of high importance for exploring the degradation mechanisms of polychromy artworks. In this paper, GC-MS and FTIR were applied to study the changes of the primary structure (amino acids) and secondary structure of pure pig glue, egg, milk and binder with ultramarine in a simulated anoxic, dark, microthermal, compacted stable burial environment for one year. Results illustrated that all binders experienced deterioration due to the changes in individual, different groups of amino acids and the broadening of Amide A. Comparatively, pig glue owned better aging resistance because of the less changes in hydrophobic amino acids, FTIR spectrum and minimum secondary structure variations. Moreover, ultramarine accelerated the soil aging process but did not bring extra influences on the primary structure.