Pages from inside of document showing the curled corners.

Parchment is dried out, treated animal skin. It is significantly more durable than paper or papyrus. The process of making parchment involves stretching the skin out over a frame before scraping and drying it.[1] 

Usually parchment is made from calf, goat, or sheep hide. When calf skin is used, it is also called vellum. The younger the animal used, the higher quality the finished product will be. After the skin is collected, the hair and remaining tissue is removed before it is stretched. Then it is scraped with a special knife. To ensure proper tension, the skin is wetted, dried, and scraped repeatedly until it has the right thickness while still stretched over the frame. [2]

Sometimes parchment was made from the skin of unborn animals. After it was cleaned, it was soaked in lime and scraped repeatedly to remove any flesh that would otherwise rot and cause the parchment to smell bad later on. It was then rubbed with pumice after being soaked with water and coated with chalk dust to make it whiter. Parchment is dense (denser than paper or papyrus) and it is much more expensive. After a while it can begin to curl at the corners.[3] This curling can be seen on the subject document. The flesh side of parchment has a darker color than the hair side but it could better absorb ink, so it would typically become the writing side. Because of the smoothness of the skin, old ink could be scraped off and new text could be written over the old surface, giving rise to palimpsests.[4]

Parchment is more costly than papyrus or paper, but it also lasts longer than either.[5] Because parchment was available and durable, it was a common writing material of the past. The articles of confederation, constitution, bill of rights, and declaration of independence were all written on parchment.[6] The fact that they have survived today along with the countless other parchment documents is a testament to its durability.

Iron-gall ink was used for writing on parchment. The key ingredient is gallic acid. Gallotannic acid can be made by crushing the galls from oak trees. This acid can then be turned into gallic acid by mixing it with water. The final ink is a mixture of the gallic acid, vitriol, and water. Gum arabic could also be added in as a medium.[7]