Removing Varnish — VE, 2018-04-05
Gamvar is very easy to remove if you want to repaint part of the painting. Use cotton wool (cotton) wrapped around a skewer, moistened with odorless mineral spirits, and roll the cotton over the area where the varnish needs to be removed. Replace the cotton frequently, until no more varnish is getting on it. If you do this carefully, you might be able to get by without having to remove the varnish from the whole painting. Once the varnish is off, wait to begin repainting until all the solvent has evaporated, perhaps a day or two.
If you applied the varnish before the paint was well cured, there’s the possibility that some paint will come off with the varnish, in which case you might have some retouching to do. After the retouching, wait six months before re-varnishing, and all should be well.