The Creation of Illuminated Manuscripts .
In addition to preserving treasured texts and images, medieval illuminated manuscripts bear witness to the collaborative efforts of an array of highly skilled craftspeople. The first in this line of artisans was the parchmenter, who prepared sheep, goat, or calfskin for use as a writing surface. The skin was first steeped in lime, and the hair and flesh carefully scraped from the surface before it was stretched tight over a frame, covered with chalk to remove excess fats, and allowed to dry. After further scraping with a moon-shaped blade, the skin was removed from the frame and cut to size. With parchments made of either sheepskin and calfskin, the hair side tends to be more cream-colored than the whiter flesh side, and the remnants of the hair follicles can sometimes be seen as small dots. Although in general terminology all writing skins are referred to as parchments, true parchment is made from sheepskin; the term "vellum- refers to parchment made of calfskin. Parchmenters the world over have most often made writing surfaces from the skins of sheep, cattle, or goats, but writing has also been found on the skins of gazelle, antelope, stags, and even ostriches.
The scribe's work began when the sheets of parchment or vellum were delivered either directly from the parchmenter or from the stationer who had ordered the book. First, the scribe checked the skin for holes and stains, scraping it with a knife or rubbing it with pumice stone to raise a slight nap on the surface. This gave a pleasing appearance to the skin, and also helped retain the ink and prevent it from spreading as it might on a smoother surface.
The next stage was to rule the sheets. Taking a few at a time, with the cream-colored hair side and the whiter flesh side alternately upward, the sheets were folded and pricked through with an awl or a knife point; the resulting "prick marks- indicated the margin and showed where the lines were to be ruled.