Parchment is animal skin that has been prepared for writing or printing without being tanned into leather. Though both materials start as raw animal hide, the key difference is chemical: leather is treated with tannins that permanently alter the skin’s protein structure, while parchment is soaked in lime, stretched on a frame, and scraped thin, leaving the collagen rearranged but not chemically changed. This distinction gives parchment a completely different set of properties, from its smooth writing surface to its sensitivity to moisture.
How Parchment Differs From Leather
The confusion between parchment and leather makes sense. Both come from animal hides, and both are durable enough to last centuries. But the production methods diverge at a critical step. Leather goes through tanning, a process where tannins (naturally acidic compounds from bark, plants, or synthetic sources) bond with the collagen fibers in the skin. This makes leather flexible, water-resistant, and chemically stable, but also permanently acidic.
Parchment skips tanning entirely. Instead, the raw skin is soaked in a lime solution to loosen the hair, then stretched tightly on a wooden frame and scraped repeatedly with a curved knife. The parchminer alternates between wetting, scraping, and drying the skin to achieve the right thickness and tautness. Because no tanning agents are introduced, the collagen fibers reorganize under tension but remain chemically intact. The result is a stiff, opaque sheet with a smooth surface that holds ink beautifully.
A final finishing step sometimes involves rubbing the surface with pumice as an abrasive, followed by chalk, to create an even better surface for writing or printing.
What Animals Are Used
Parchment is typically made from the skins of three animals: goats, sheep, and calves. Each produces a slightly different material. Goatskin tends to be thicker and more textured. Sheepskin is common but can be greasier and less uniform. Calfskin produces the finest, smoothest result.
The term “vellum” refers specifically to parchment made from calfskin (the word comes from the French “veau,” meaning calf). Medieval vellum was also sometimes made from the skins of very young animals, like lambs or kids, which produced an even finer, thinner sheet. Vellum is generally considered higher quality than standard parchment, though the two terms are often used loosely and interchangeably today.
What Happens to the Collagen
The reason parchment behaves so differently from leather comes down to what happens at the fiber level. When skin dries under tension on a stretching frame, the collagen fibrils gradually align in the direction of the strain. Research using X-ray imaging has shown that at low strain levels, the fibers simply reorient, becoming more parallel and organized. As the tension increases, the forces start transferring directly to individual fibrils, locking the structure into a rigid, sheet-like form.
In tanned leather, those same collagen fibers are chemically crosslinked by tannins, which keeps them flexible even when wet. Parchment’s fibers aren’t crosslinked. They’re held in place purely by the physical reorganization that happened during drying. This is why parchment is stiff and flat when dry but extremely reactive to moisture: add water, and those fibers start moving again.
Why Parchment Is Sensitive to Humidity
Parchment’s biggest vulnerability is moisture. Because the collagen was never chemically stabilized through tanning, it absorbs and releases water readily. In humid environments, parchment can cockle, wrinkle, curl, and distort as the fibers swell unevenly. Some degree of cockling and gentle undulation is normal in old parchment and doesn’t necessarily mean the material is deteriorating. But repeated swings in humidity cause the skin to expand and contract, which can crack and flake any ink or pigment sitting on the surface.
For preservation, the ideal conditions are temperatures below 65°F (18°C) with relative humidity between 45% and 60%. Stability matters more than hitting a perfect number. Fluctuations are what cause the most damage over time, as the parchment constantly adjusts to its environment.
Parchment Paper Is Something Else Entirely
If you’ve encountered “parchment paper” in a kitchen or craft store, that’s a completely different product. Modern parchment paper is made from cellulose fibers derived from trees or plants like cotton and flax. It has no animal skin in it. The name stuck because the paper mimics some visual qualities of real parchment, but the two share nothing in terms of material, production, or properties.
Historical Use for Manuscripts
Parchment was the dominant writing surface throughout the medieval period, used for everything from religious texts and legal documents to personal correspondence. Its smooth surface accepted ink cleanly, it could be folded into book pages (codices), and it lasted far longer than papyrus in European climates. Many surviving medieval manuscripts, some over a thousand years old, are written on parchment or vellum.
Today, real parchment is still produced in small quantities. Some government documents, diplomas, and religious texts are printed on it. Artists and calligraphers use it for specialty work. But its primary significance is in preservation and conservation, where understanding the material helps archivists protect the manuscripts that have survived from centuries past.