Parchment:

Parchment, the eventual successor to wax, wood, and metal, is a material made from animal skins which have been cleaned, dehaired, stretched, then ultimately cut and dried. The early stages of the cleaning and dehairing process generally took place over the course of several days, during which the parchment maker would soak the skin for several days "in a bath of lime solution to loosen the hair," making it easier to eventually remove the hair.  Hair removal and cleaning was generally done by placing the skin "over a beam of wood," working the skin with "a gently curved, two-handled blade" in a process called scudding.  All of this led to what Graham and Clemens argue in their Introduction to Manuscript Studies was the most critical stage in the process: "drying the skin under tension" and stretching it out on a frame (10).  The skin was attached and stretched on a medieval herse; while none of these machines have survived, evidence suggests "that the herse was sometimes square, sometimes round," and that the animal skin was attached by cords to the wooden frame of the herse (Graham and Clemens 11). 

Though the hair is entirely removed from the animal skin before the transcription process, it is possible to determine which side of the parchment once had hair -- the "hair side" -- and which side of the skin faced inward -- the "flesh side."  The hair side of parchment is identifiable by the presence of hair follicles, which appear in the form of tiny dots, almost like minute pinpricks, across the surface of the skin. These follicles can be spread across the entire skin or clustered in smaller, darker patches, generally denoting the line of the animal's backbone (Graham and Clemens 11). In the example to the left, the follicles are clustered in the bottom left corner; in the example to the right, the follicles are smaller and are spread across the entire page.