The enduring legacy of vellum: why some laws are still written on skin
While most of our history is recorded on paper, certain vital documents—from British Acts of Parliament to the Torah—rely on the incredible durability of vellum. This isn't just a tradition; it is a triumph of ancient chemistry and animal skin preparation that can last over a millennium.
Vellum is a highly refined writing material prepared from animal skin, traditionally calfskin, though the terms 'vellum' and 'parchment' have historically been used interchangeably. The etymology of vellum traces back to the Old French 'vélin' and the Latin 'vitulinum,' meaning 'made from calf.' While some modern practitioners reserve the term specifically for calfskin, others use it to denote a higher quality of skin regardless of the animal, which could include sheep, goat, or even deer.
The manufacturing process is a meticulous cycle of tension and texture. It begins by soaking the skin in water and lime (calcium hydroxide) to remove hair and soften the membrane. The skin is then stretched on a wooden frame called a 'herse' and scraped with a crescent-shaped knife known as a 'lunellum.' To achieve the necessary tension, makers alternate between scraping, wetting, and drying the skin. The final surface is smoothed with pumice and treated with chalk or lime to create a writing-ready finish.
This labor-intensive method produces a material far more durable than paper. For instance, the 12th-century Winchester Bible required approximately 250 calfskins, and the 1455 Gutenberg Bible included a vellum edition for high-end collectors. Because vellum can last over 1,000 years in stable conditions, it remains the choice for prestigious diplomas and religious texts. However, it is notoriously temperamental; it requires a precise environment of roughly 20 °C and 30% relative humidity to prevent it from becoming brittle or prone to mold.
Source: Vellum
