Usually, egg tempera is painted onto gesso on a rigid substrate (usually, wood). I'm planning something different, and wanted first to find out whether egg tempera could be painted directly onto vellum. Two animal proteins in contact -- you'd think they would bind well. So far, so good. I'm working with lazurite powder from Cornelissen's, very brilliant in hue, if a little gritty; titanium white watercolour, for body and opacity, and milkiness; and two tubes of iron oxide -- rust from a horse-trough in the case of the redder colour -- sent by a good art friend. Eggs come from the local supermarket. Egg tempera is very enjoyable to work with, so far. It dries fast, but on vellum not as fast as it would on gesso. It can be washed to some extent, pooled, and pushed around a little for interesting effects. Degrees of impasto appear possible. It layers beautifully. Washing white over the top of translucent colours transforms them into a new palette. And unlike those meticulous painters who work on gesso, if I don't like something I've done I can simply scrape my dry paint back down to the vellum, and start again. Whether the egg will stay on the vellum is another matter. In my bones I feel it ought to remain flexible enough to rest there indefinitely. But in a few hundred years my bones will be in bad shape and so may the egg. A trip to the British Library is planned to help answer this question. Meanwhile, there is a society of egg tempera painters to refer to -- their forums are especially useful -- and the inimitable John at Nuncketest.