Yes, and I have not even got to try all the various mixtures yet. The casein does make the oil paint dry really fast. As to how long the mixture with oil paint will last, it should last at least as long as the Casein. The chemical compatibility between them is good too, they actually will crosslink according to a few resources I had read. That said, there is very little scientific study done on Casein with other mediums compared to Acrylic, Oils, or watercolor even. There are a few blogs and articles about Casein as well that held quite a bit of historical information. It seems like Casein is one of the oldest mediums in the world, having been used since prehistoric times.

You are right–it sure is darn hard to find any research or historical info on casein. Have you used casein + oil paints regularly? Or have you noticed how they last? I am real tempted to play with this combo more. Do you think I could still call it “oil paints”? Or would it have to be “mixed media”?

Cannot say I have used it regularly, the samples I made on paper some years ago are currently in storage. When I get back to get that box from their storage location I will see about how they have done. Last check before storing, the layer looked as good as when I painted the sample (a mixture of ultramarine blue and transparent oxide yellow oil paint). The resulting gray paint was in excellent shape and still flexed fine with the paper, though I did not try folding it through the sample (not trying to break my sample yet). The sample was thinly applied, not a heavy impasto at all, which is recommended to avoid for Casein or oil on a flexible surface such as paper.

I would still call it oil paint, as oil painters add all sorts of mediums to their artwork very frequently. Sometimes they add alkyd, wax, resins, varnish, spirits of various types, chalk, egg, or any number of other additives. So long as it looks like oil when finished, it largely doesn’t make too much of a difference. The matte quality of Casein does have a very different look than most oil though. The major thing to remember is that Casein is more brittle and less flexible than oil, so if mixing it in with your oil, do it in the earlier layers and be sure to add less in later layers. Flexible > inflexible.

Nadia_gnar, you are welcome for the link, big thanks go out to Ms McKee for sharing her findings in a nice condensed form for us.

Trond, that was my finding as well. It was when I noticed the oil in the Shiva line of paint that I started researching the compatibility of the mediums.

DB Clemons has a ton of information on Casein making and usage for a number of purposes. He has a website and a blog both having lots of information or examples, he even “recently” proposed the idea of making and selling tubes of Casein paint, which I would be interested in buying at least some.

There are more various sites on the web with some information on making Casein blue for use as a binder for a number of things, and a very informative brochure on usage and methods of making and using it from the mid 1900s that I read through, though I have been having problems finding the link again more recently.