I now know that it’s not advisable to dilute oil paints with odorless mineral spirits or other solvents for a washy underpainting, as there may be problems with binding (among other issues). Some folks advocate just painting from the tube without solvents, and scrubbing the paints around, but I enjoy the fluidity of a more liquid underpainting.
I’ve become interested in casein as an underpainting, and recently purchased and watched James Gurney’s “Casein Painting in the Wild” video available from his wonderful blog, http://gurneyjourney.blogspot.com. I noticed that with his casein plein air paintings, he starts out with a very watered down wash of casein mixed with water and then builds up with more opaque layers of casein. I’m wondering whether this very watery casein underpainting in itself (without the layers of opaque casein), painted on an panel primed with acrylic “gesso” would have sufficient binding power (both to the acrylic gesso and to subsequent layers of oil paint).
Thanks so much. Follow up question: I read a comment from casein painter D. B. Clemons: “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.” I’ve also read of artists combining oleogel (which is basically linseed oil) into casein tube paint (Richeson brand).
So my questions are: (1) If I mix oil paint into a mixture of casein emulsion and water (I’m thinking Richeson’s Shiva Casein Emulsion), is this good practice/archival? (This seems to be a good way to get a more liquidy underpainting as opposed to using odorless mineral spirits mixed with oil paint if the bonding of everything will be good). (2) If I mix a watered-down casein paint into oleogel (or linseed oil), same question. (3) I know that casein paint by itself cannot go on oil ground. However, can I use an oil-based ground under such mixtures of casein (or casein emulsion) with linseed oil/oleogel (or oil paint)?
Here’s the site where D. B. Clemons makes his comment quoted above:
http://www.conceptart.org/forums/showthread.php/250197-How-do-you-use-casein-in-relation-to-oils See also http://linesandcolors.com/2016/12/01/painting-with-casein-paint/
Thanks again!
Thank you so much for that super helpful response. I’ve played around a bit, and now find that using the Richeson Shiva Casein Emulsion (ratio 1:5 medium to water as recommended) instead of just water to control the casein paint is working quite well, as it both thins the paint for the effects I want and slows the drying time just enough to not be blotchy in a wash. I’m pretty satisfied that this will be the way to go, whether I’m doing just a casein painting or using it as an underpainting. Thanks again!
Sorry for the late response. Richeson recommends casein as an underpainting for oils, and instructs that it can be used over acrylic dispersion painting ground (gesso). They caution against applying casein over any ground containing oil, so that would also include alkyd and traditional “oil gesso” formulas. I think the proposed thin underpainting would be a sound approach, avoiding impasto and broad, thick applications. Ampersand recommends a rigid (panel) support for casein, so I would follow that advice and avoid using stretched canvas, even with thin applications.
http://www.richesonart.com/products/paints/richesoncasein/richcaseinfaq.html
https://ampersandart.com/casein.php
I am afraid that rather than having the benefits of both mediums, mixtures like this generally end up having the deficits of both and lack the virtues of either. Certainly very small amount of oil can be, and are, added to casein emulsions. A representative from Richeson mentioned that they add small amounts of oil to their Shiva Casein paints during our materials session at CAA this February. This is probably only added as a plasticizer and for tube stability. Casein is a very brittle binder and a tiny amount would probably lessen this to a small extent. I would still not recommend painting casein paints on canvas.
There are technical reasons not to add oil in substantial amounts to casein. Casein containing large amounts of oil are known to yellow strongly. Mayer strongly cautions against this. It is certainly true that mixing oil paint with casein paint is not really creating an emulsion unless the two were vigorously mixed and mulled and even then a proper emulsion is probably not created. You would likely create a paint that had swirls of very brittle casein between or surrounding bands of very flexible (at least initially) oil paint. That is a perfect recipe for cracking and paint delamination. Additionally, it is really not technically possible to create a paint that really straddles the emulsion inversion point and allows for alternating between water and organic solvents. These mixtures are physically far more complicated than this. This subject was brought up many times by scientists at the recent tempera conference hosted by the Dorner Institute in Munich.
Coincidentally, the mixtures that you mention actually remind me of the “mixed technique” popularized by Max Doerner where egg tempera/oil/resin emulsions were painted into oil glazes. These were very successful at creating effects that were hard to accomplish by other means but unfortunately resulted in paintings that were prone to cracking and delamination, excessive yellowing, and solvent solubility.