Q. What are the advantages and disadvantages of using a product like Shiva Casein Varnish? Are there any other casein varnishes that are good?
Rolling Meadows, IL
A. First, I assume youre using the varnish only with casein paints, since thats what the product is made for; it shouldnt be used with any other kinds of paints such as watercolors, acrylics or oils. Although its fashionable to mix media, youll risk making a physically vulnerable and unstable painting. If you do mix your media, use one dominant paint material, with perhaps one or two secondary materials scattered throughout the picture. Of course, this is a “rule” that begs loudly to be broken, and its so often ignored that painting conservators are assured of lifetime employment.
Second, if youre using this product to varnish a finished casein painting, that would be an acceptable use, but its unnecessary. Casein paintings are meant to have a matte, not a glossy, surface, and can be protected by framing behind glass.
If youre using the casein varnish like a medium, mixing it into the paints as you apply them, then remember that if a product label describes the materials use, its not meant to be used in any other way. So, if the product label says “varnish” then the product is meant to be used as a final coating, not as a medium. However, you could use the product as part of a medium, as long as the use isnt excessive (I wouldnt add more than 10 percent of the varnish, by volume, to a mixture of color). Even though casein is relatively insoluble once its dry, you can run the risk of producing more fragile paint layers if you use too much of the varnish. If youre trying to increase the gloss of the paints, again remember that casein paints arent glossy paints.
Finally, as to your second question, I know of no casein products on the market other than Shivas.
Mark Gottsegen is an associate professor of art at the University of North Carolina at Greensboro.