Interactions between inorganic pigments and rabbit skin glue in reference paint reconstructions
The thermal degradation of rabbit skin glue, a collagen-based proteinaceous material used as a paint binder in paintings, was investigated in this paper. Paint reconstructions of the glue on its own or mixed with azurite (Cu3(CO3)2(OH)2), calcium carbonate (CaCO3), hematite (Fe2O3·nH2O) and red lead (Pb3O4) were analysed using a thermoanalytical approach. This method enabled us to investigate the interactions between the glue and pigments before and after artificial indoor light ageing. The study was carried out using differential scanning calorimetry, thermogravimetry and thermogravimetry/FTIR analysis already successfully employed to characterize the paint binders. The results highlighted that all the inorganic pigments interact with rabbit skin glue, thus decreasing the thermal stability of the binder. Light ageing further decreased the thermal stability of pigmented paint replicas, suggesting a moderate increase in the rate of the degradation.
KeywordsRabbit skin glue Azurite Calcium carbonate Hematite and red lead Thermogravimetric analysis Differential scanning calorimetry
This work was supported by PRIN 2008 (Project No. 2008XXAMZT) and PRIN 2010/2011 (Project No. 2010329WPF) funding from the Italian Ministry of University and Research.
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