C 6.11. Curling

This is a wave-shaped deformation of the parchment.

There is often a slight curling of the parchment surface in high-quality and well-preserved parchments. In most cases, such slightly wavy surfaces are easy to flatten under slight pressure. The fibrous structure of parchment, consisting mainly of protein collagen (≥95%) and elastin molecules (≤5%), is based on a strong structural network. Within specific molecular degrees of freedom, the extraordinarily long (approx. 300 nm) collagen microfibers (fibrils) have the ability to balance the internal stresses in the parchment as the environmental conditions (temperature and humidity) change. As a result, the surface of the parchment becomes slightly wavy, thereby retaining its flexibility.