When coming back to work on an oil painting which has already dried, you may occasionally have this problem. You begin to paint or glaze and you notice the new paint layer seems to be separating.
Your newly applied oil paint beads up on the surface. The new paint isn't adhering.
I've used a lighter paint color in the image below so you can see what this looks like. The paint is crawling or drawing up into drops as a result of high surface tension.
This seems to happen when the dried paint layers below contain a lot of oil. This may also be referred to as a closed surface.
This adhesion loss or surface tension usually happens in the upper or final layers of the painting.
If you're following the lean to fat rule, the top layers likely contain the most oil or painting medium. The oil or painting medium dries to a glossy surface.
The new layer of oil paint or glaze can't stick to this glossy surface. The new paint crawls, beads up and won't properly adhere.
Use a clean dry brush. Double check to be sure your painting is fully dry to avoid lifting or smearing previous paint layers.
Cover the surface with a very thin coat of turpentine.
You can choose to coat only the section you're working or the entire painting. Once the turpentine evaporates or dries, you can resume painting. The turpentine or solvent relieves the survace tension, opening up the painting surface.
The adhesion problem should be solved.
Author: Sonia Reeder-Jones