Comment by Daub

True… what I said only applies to canvas paintings. I should have made that clear.

The longevity of murals is easy to account for: the paint is applied to wet plaster, in that way becoming part of the wall. That is why the murals of Pompeii survived.

> Canvas is almost always coated with gesso which at the time would use rabbitskin glue as binder, no flax there.

You are right about the rabbit skin glue, but wrong about the gesso. As I recal, traditional Gesso is a mix of glue plus titanium white powder and is very brittle, generally unsuited to a flexible support such as canvas. A canvas painter would more likely use something flexible like a mix of pigment and rabbit skin glue, or pigment and egg protein or pigment and oil.

I thank god for modern primers. Using modern primers, I can prime a canvas in two days. An oil based oil primer could take months to dry.