Sheepskin parchment ‘used to detect early document fraud’

Sheepskin may have been the preferred parchment for use in legal documents in Britain between the 16th and 20th centuries because it made it easier to detect fraud.

That’s the conclusion of research published in the open-access journal Heritage Science, which says that most legal documents from this period were handwritten on sheepskin because of its high fat content, which served as a security feature.

“Removing fat during the parchment making process can cause the layers within sheepskins to separate more easily than those of other animals,” according to Sean Doherty of at the University of Exeter, who is the corresponding author for the study.

“To make fraudulent changes to documents after signing, the original text would have to be scraped off,” he said. “This could cause the layers within sheepskin parchment to separate and leave a visible mark on the document, resulting in the fraud being easily detectable.”

The team of researchers from the Universities of Exeter, York and Cambridge looked at 645 samples taken from 477 British property deeds dating from 1499 to 1969, and performed mass spectrometry on proteins extracted from the samples to identify the animal used to make the parchment.

Depth Perception: An Important Authentication Tool for Security Features

All 645 samples contained proteins characteristic of animals from the Bovidae family, which includes sheep, goats and cattle. 622 of the samples contained proteins characteristic of sheep, indicating that they were made from sheepskins. The remaining 23 were made from either sheep or goatskins but the individual species could not be identified due to a lack of characteristic proteins.

“We were surprised to discover that the deeds were made almost exclusively from sheepskin, as previous research has indicated that other non-legal documents were written on skins from a range of species,” continued Doherty.

The authors caution that the presence of goatskin parchment in the documents studied cannot be ruled out as proteins characteristic of goats in the samples may have been degraded during storage, potentially affecting their analysis.

Sean Doherty said: “Historic legal deeds are one of the most abundant resources in British archives but are often considered to be of limited historic value. Our research demonstrates that, as physical objects, historic legal deeds can be used to explore centuries of craft, trade and livestock economies.”