Gamvar: Use if your oil paints were mixed with up to, but not more than, 25% cold wax medium to oil paints only. If You have used more than 25% cold wax medium to your oil paints, ONLY USE COLD WAX MEDIUM as your final varnish!
When painting is touch dry, not tacky, firm to touch, when your fingernail does not dent it, you can then put a layer of Gamvar on top (after first oiling out). Mary (customer service representative at Gamblin Colors) does not recommend retouch varnish as it has damar resin which is brittle. Rather, she recommends oiling out, THEN gamvar. Wait 48 hours after oiling out before varnishing. Evenly and thinly after oiling out, apply Gamvar. Apply with natural bristle brush – avoid synthetic brushes as they hold too much varnish in their bristles—really want the most MINIMAL amount of Gamvar applied to a painting. You could mop up excess, but just try to apply the most minimal amount of varnish. Never put the 50:50 gamsol:galkyd over the gamvar as it will remove the gamvar.
To view Gamblin Colors Oiling Out Video, click here. The video is at the bottom of the page.