The Birds painting is the first casein/oil painting that I finished. I was researching how to get oil paint to dry quicker as well as under painting techniques and started to look at alternative mediums. I tried egg tempera, gouache, acrylic, and various mixtures of oil. Egg tempera was initially the winner.I really liked the matte finish and how it contrasted with the glossy oil on sparingly added on top. Turns out that egg tempera is hard to come by without making yourself. The tubes I bought were from Italy and cost 2-3 times the equivalent in oil. So I dug in deeper and found casein.It had much the same qualities as egg tempera, was produced here in Wisconsin (Shiva),reasonably priced and turned out to mix better as well. Event better, Shiva also produced oil paints with the same pigments used in the casein (or at least extremely similar), so the top oil layer is less of a crap shoot. It is working well. It does make me appreciate oil more to work with casein. It dries very quickly and close to a whole value darker than it is when it is wet, but the final surface is great...like cement. It's dry and full of little brush textures which plays off of oil well.
