C 6.14. Contraction, shrinkage

Shrinkage is a reduction in the volume and dimensions of the parchment.

The localised shrinkage of the parchment is almost always due to the degradation of the parchment, which is the decomposition caused by the oxidation and hydrolysis of the long (ca 300 nm) collagen molecules, which is neatly twisted into a left-handed α-helix by hydrogen bonds, into shorter molecules. The changed chemical properties are accompanied by a change in the density of the parchment and flexibility is lost.