May 7, 2010
I thought I would do a post on the preparation of the binder, or medium, that I am currently using for my paintings on vellum: glair. I am also thinking of it because today I had a magical visit to the rare books library at Dartmouth College, where I pored over some medieval manuscripts, which I'll share soon. According to Daniel V. Thompson, in his book The Materials and Techniques of Medieval Painting, glair was one of the main binders used to make paint––when added to pigment––for manuscripts. Another important binder was gum arabic, used mainly after the 14th century; it is now used to make watercolor paints.
The first step in making glair is to separate the yolk and the white, since you use just the white. Put the egg white in a non-reactive bowl and beat it until it has stiff peaks. I use a hand held electric mixer, which makes the job a lot easier.
Then we wait.
After 3 or 4 hours, tilt the bowl and a clear yellowish liquid will creep out from under the white froth; this is the glair. Every hour or two tilt the bowl again to draw off the liquid; this process can go on for the entire day. Finally, there is no liquid left and the froth that remains is dry and stiff. I get about a tablespoon of glair from a large fresh egg; it doesn't sound like a lot, but because I'm doing such small paintings, it is enough for 2 or 3. It keeps quite well for several days in the refrigerator, a week or more. I like this medium for a couple of reasons: primarily because it yields very rich color, but also because I'm using a local ingredient: eggs from 'Alex's Birdberries', close by in New Hampshire.