The Manufacture of Goldbeater’s Skin, Transparent Parchment, and Split Parchment ¹

Palaeoproteomics and microanalysis reveal techniques of production of animal-based metal threads in medieval textiles

“…Although of later periods (between the sixteenth and eighteenth century), the Italian production of violin’s “cat-strings” made from the muscularis externa layer of the small intestines of sheep was known to be of the highest quality 64 ; the function and properties required for the strings are quite similar to those of membrane threads, such as strength and flexibility. Perhaps the closest equivalent to membrane threads is goldbeater’s skin, a gut membrane prepared from the outer or peritoneal coat of cow’s caecum 65 . It holds its name from the production of gold leaves, in which the membranes were placed between sheets of gold to keep them separated during the goldbeating process 63 , 66 , 67 .…”

“…However, in membrane threads, gilt-silver leaves must adhere to the substrate, either through its natural adhesive properties 3 , or through the use of a binder, which might be collagenous in nature (as can be suggested by proteomics), or non-proteinaceous. To make goldbeater’s skin, two sheets of gut “skin” were coupled by binding their muscle fascia layers together 65 , a morphology that seems to match only with sample 81.01.01bis. However, similar membrane layers and preparation techniques might have been used, and membrane threads could have been prepared in goldbeating workshops.…”