During the Middle Ages scribes tended to be monks working to make copies of religious books. Some scribes were hired artists that had wealthy patrons who wanted their own personalized copies of the great works. Illumination was mostly used for decorating the pages of books and often described the text in stylized pictures. One of the most commonly illuminated books was the Book of Hours, which was a collection of the text for each liturgical hour of the day and often included calendars, prayers, psalms and masses. There are many great extant examples of these for modern scribes to study.
What do HFS scribes do? HFS scribes study period manuscripts and produce documents, which accompany awards that are presented in court.
There are many different styles of calligraphy and illumination. These scribal forms of the art have evolved over the centuries and were adapted and altered to suit the needs of each culture it moved through. Islamic illumination excelled at intricate vine-like designs, and in many Christian texts, saints were represented in a very stylized manner to better show their holy presence.
Scribal Calligraphy - putting words on paper (or vellum, parchment, papyrus, etc...). This is usually done with calligraphy nibs and ink and sometimes with brushes depending the style.
Illumination - decorating the page. This is commonly done with gouache (opaque watercolor). Some period pigments however can be toxic and those must be used with caution. Acrylics and oils are not used due to their modern materials. Gold leaf is used with medieval adhesion recipes (gesso, fish glue, Armenian bole, etc).
Wordsmiths - coming up with flowery wording for scrolls. This is where someone with a poetic bent can get involved.
Note: We call them "scrolls," but they're really documents, as the term documents often refers to the more legal and official paperwork that we're sometimes forced to endure. Actual scrolls are wound on sticks.