Abstract

When parchment and leather are subjected to humidity changes there are corresponding changes in temperature due to the gain and loss of water. This paper examines, refines and applies to parchment a thermal technique previously used for the analysis of the condition of historical leather. The magnitude, duration and decay of the thermal response of modern and historical parchments have been determined. The thermal response for historical parchments is different to those which are modern. Generally, relaxation times are slower for rehydration when compared to dehydration. Historical parchments are gradually changing from a collagen like structure to a more gelatin-like structure. No significant changes in thermal response was observed within an artificially aged set of modern parchments using this technique. This suggests that artificial ageing does not reproduce all of the changes found in historical parchments. The thermal response and thermal decay half-life of leather is much smaller than that of parchment on a mass per unit area basis.When parchment and leather are subjected to humidity changes there are corresponding changes in temperature due to the gain and loss of water. This paper examines, refines and applies to parchment a thermal technique previously used for the analysis of the condition of historical leather. The magnitude, duration and decay of the thermal response of modern and historical parchments have been determined. The thermal response for historical parchments is different to those which are modern. Generally, relaxation times are slower for rehydration when compared to dehydration. Historical parchments are gradually changing from a collagen like structure to a more gelatin-like structure.

No significant changes in thermal response was observed within an artificially aged set of modern parchments using this technique. This suggests that artificial ageing does not reproduce all of the changes found in historical parchments. The thermal response and thermal decay half-life of leather is much smaller than that of parchment on a mass per unit area basis.