Hello,
thanks a lot for all your comments and suggestions.
I know that it is not recommended to varnish or coat an egg tempera painting. In my case I use ET for the underpainting because it allows me a very precise drawing and it dries really fast. The problems come when I add oil. The base is so terribly absorbent that I can’t manipulate the first oil layer. Soon after I start with oil paint doesn’t flow normally, which doesn’t allow me to keep going.
I have done many tests and when I isolate ET with Paraloid B72 or an oil medium (1 part stand oil + 2 parts turpentine, for example) the brushability improves considerably. The base is still absorbent, but it allows me to work on it.
Is there a better alternative to an isolating varnish? I am concerned about the preservation of my paintings, but this issue just doesn’t let me keep painting.It may be a silly question, but… would it be more reasonable to apply an isolating coat with an emulsion medium? I mean, mixing an oil medium with an ET medium. For example, the medium I am using to grind my ET colours with 1 part stand oil + 1 or 2 parts turpentine. Any other suggestion maybe?
Thanks again.
Max
Varnish on an egg tempera painting is an aesthetic decision. In truth, more proto- and Renaissance ET paintings were originally varnished. That is up to you.
I worry more about the solubility of interlayered varnishes. I actually think that if you keep your intermediate layer very minimal and cover the entire surface with later layers of oil paint, there is nothing technically wrong with a very thin application of a thinned oil or even a diluted alkyd medium. Please read over our comments about “retouch varnish” and “oiling out” as those cover similar issues. You also want to make sure that the intermediate layer is only fat enough to only reduce absorbency to the extent necessary and not create a slick film which may cause interlayer cleavage. I see no advantage of using the fatty emulsion over the very thinned stand oil (other than perhaps drying time) and I have seen unpigmented egg-oil emulsions separate into their constituent parts unlike pigmented egg-oil emulsion paints.
