[Todd Shaffer]

Try using Liquin by Winsor Newton. It is an alkyd, will dry quick, and will not be removed by mediums or paint. I don't do much glazing, but I do use Liquin to rewet a dry paint area so that I can regain the wet-into-wet look. I also use it to eliminate the blonding effect of dry paint. I think I can safely assume Rockwell would have been thrilled to have Liquin. Windsor & Newton does not recommend Liquin being used as a final varnish, but I know a few painters who use it for that.