Changes in some properties of aged and historical parchment

The starting point for the research reported here is the poor state of parchment documents at many sites in Egypt: museums, stores, libraries and excavation areas. Modern parchment samples were submitted to accelerated ageing at different temperatures (70°, 100°, 134 °C). Several properties (shrinkage temperature, mechanical strength, humidity sorption, colour change) were measured and compared with the same properties of historical parchment samples from the 5th, the 18/19th and the 20th centuries. The applied methods seem to be apt to determine the state of deterioration, which is considered the first step of conservation. The shrinkage temperature was measured using the micro-hot table technique, which is considered to be a non-destructive method because only very small samples are needed for the measurements.