To continue the theme of Conservation for this year’s Explore Your Archive week, today’s blog is all about parchment and features some of our parchment documents.Parchment is made from specially prepared, untanned skins of animals which are mostly sheep, calves and goats. Vellum is a higher quality skin made from a young calf. Without scientific analysis, however, it is very difficult to determine what animal the membrane is from and how old it is.
To make parchment, the original animal pelt needs to be dehaired. The pelts are soaked in water for about a day to remove all blood and grime. It is then taken out and put into a dehairing bath to remove the hair. This usually lasts about 8 days but in winter this can last up to 2 weeks. The dehairing liquor was originally made of rotted, or fermented, vegetable matter but by the Middle Ages, this included lime. The pelt would be stirred with a wooden rod in a stone vat about 2 – 3 times a day.
Once it is removed from the dehairing solution, the skin is then soaked in clean water so the skin can be ‘worked’. The skin is then stretched on a frame, which would be as simple as a wooden frame with nails stretching the skin. This would be left open to the air so they could be scraped with a knife to remove the last bits of hair and get the skin to the right thickness. As the animal skin is made from collagen, this would form a natural glue whilst it was drying so the skin would keep its stretched form once removed from its frame.
To make the parchment more aesthetically pleasing or more suitable for the scribes, special treatments were used. One treatment included rubbing pumice powder into the flesh side of parchment while it was still wet on the frame was used to make it smooth and to modify the surface to enable inks to penetrate more deeply. Powders and pasted of calcium compounds were also used to help remove grease so the ink would not run. To make the parchment smooth and white, this pastes (starch grain) of lime, flour, egg whites and milk were rubbed into the skins. This is why parchment will have a rough and a smooth side.Unsurprisingly, the oldest document we hold in our archives is recorded on parchment. This is [DV 14d Outsize] 435324 – Agreement between Simon, Bishop of Worcester, and Waleran [de Beaumont], Earl of Worcester, settling various differences which had arisen between them. We believe the document dates from between 1139 and 1143, based on the names that appear in it, despite the date 1160 being recorded on the actual document!