5: Leather and Parchment

Leather, parchment or rawhide are largely represented in museums, libraries and archive collections as objects for everyday use, and artistic or spiritual expression. Although both made from animal skin, the manufacturing process of leather and parchment differs, thus leading to two different materials from their appearance, properties, use and reactivity towards the environment. The chapter details the different steps of the manufacturing process that is dependent on the desired properties of the finished product, but also on the tradition and materials available in the geographical area. The description of the structural organization of the skin, its main constituent collagen, as well as the tannin for leathers, helps appreciate the complexity of the material with its unique mechanical properties. The different factors of degradation of leather and parchment and their effects on the collagen molecule are also discussed. The chapter introduces the main analytical approaches currently employed to characterize the skin animal species, the tanning process and the collagen degradation state. Finally, a case study on the Chartres fire-damaged medieval manuscripts is given to illustrate the different scientific approaches developed to investigate the parchment conservation state and recover illegible writings.