Do any of you use casein paint, and if so, what do you think of it, and how do you work it into your oils? I was just reading a short biography on John Berkey, and it listed casein paint as one of his mediums of choice along with oil paints, and now I am just a bit curious about it.
Anyways, just thought I'd ask in case someone was feeling teacher-ly
-I often post from my phone; so please excuse the typos
I've been making my own casein paint and medium for many years. It works very well with oil paint and mediums, and acrylics too, for that matter, or by itself.
One application of casein is it can be used to create a gesso surface, like rabbit skin glue and gypsum, upon which to paint. This surface is quite absorbent, so I'd recommend applying a coat of shellac before painting on that with oils. You can use the paint in thin washes for your undertones, as you might with turpentine and oils or acrylic, and then overpaint this with oils. The benefit of using casein in this way is that it has a stronger binder in this paint layer than thinned oils would have. It accepts oil paint better in this manner than acrylics would, in my experience.
Casein is also compatible with oils when mixed together, meaning you can actually combine the two mediums, since it's a water and oil emulsifier. The advantage here is you can get the benefits of either medium: casein paint that has more body, is easier to blend, and dries more slowly due to the oil content, or oil paint that can be thinned with water, dries quicker, and looks more matte due to the casein.