How do I mount and frame vellum paper?
Q. Dear Donia,
A. Dear Matt,
Vellum and parchment are their own beasts and do not necessarily conform to the same standards as for paper.
First, there are special techniques for mounting and framing parchment (of which vellum is a subset) that need to be followed as the skin reacts more actively to changes in RH than paper does. Thus, framing would need to be done by a conservator with special experience in this sort of work if you do not want your vellum piece to be damaged in the frame. Many parchment pieces were framed directly sandwiched between backing board and the glass to provide restraint but over time, this damages the item as it wrinkles and has its edges damaged by the frame. What I see more often than I like is the vellum actually gelatinizing (becoming glue) and adhering itself to the glass due to high RH and light. A problem often found in conjunction with this is mold growth.
All this is to say that there is no easy answer as to how to mount and frame parchment on your own because of the large range of variables and training needed. The best thing to do is have it framed by a professional and then display it away from direct sunlight and in an area with stable RH.
Sorry I couldn't be more explicit but so much depends on the type of skin, its thickness, what is on the surface of the skin (printing inks, paints), and how it actually reacts to changes in RH. Each skin is unique and needs to be treated as such.
I hope this helps.