Most medieval manuscripts were written not on paper but on parchment, which typically was produced from the skins of calves, sheep, or goats. Parchment is sometimes referred to as vellum, although that term also may refer more specifically to finely finished calfskin parchment.
Parchment production is a complex process entailing many steps, which varied significantly according to region and period. In general, the process began with cleaning the selected animal skin, soaking it in a lime solution to loosen the hair, and then washing it in clean water. The skin was then scraped with a knife to remove as much hair as possible, after which it once again was washed in water. Next it was moved to a rack (or herse), where it was stretched, then left to dry for a prolonged period. While on the herse, the parchment maker scraped the skin once more, this time with a curved blade called a lunellum, which removed any remaining hairs or blemishes. Once they were taken down from the racks, some skins received final finishing with a pumice stone or treatment with a preparation of lime or chalk before they were cut to size for use by scribes. If everything had gone well, the end product might resemble the fine white parchment of Takamiya MS 76 (to the right), which is very thin and so white that you can just make out the skin’s vein structure.
A calfskin subjected to this labor-intensive process might produce as few as three and a half medium-sized writing sheets, and thus parchment was an expensive commodity. Often, imperfect parchment was used in the production of books, as exemplified by Takamiya MS 92, in which the rounded edge of the animal’s shape is still visible at the bottom of the folio. Sometimes holes are also visible in the parchment membrane. They could be original flaws or produced by stresses during the stretching or finishing processes. It is not uncommon to find that such holes were sutured to prevent further damage to the page, which also can be seen in this Bible leaf.