Thanks Marcus and I will indeed check out the threads you have chosen.
Your other suggestions are good as well. It happens that I paint in very thin layers (usually) in the Old Master layering technique beginning with a shady study and other layers follow. I think the two that have dried would be fine with varnish.
I also want to add that I checked out your site and love your work. Great use of the primary colors. Noticed the Red particularialy that you have in nearly all of your figurative works,