I'm currently trying to figure out how to resolve some of the drastically different shiny/dull patches on a couple of finished canvases before varnishing them. Gamsol's website recommends a 50/50 blend of mineral spirits and alkyd, but I'm looking for any insight from other painters who use similar methods to the one's proffered by Mark. So here are my questions:
1) When you oil out your paintings, what medium do you use for the oiling out?
2) Is there any other methodology you use for fixing paint that has dried with uneven patches of matte and shiny finish?