–2018-04-06–This post describes the drawbacks of damar varnish and modern alternatives, including specific products based on a synthetic resin called regalrez.
Uneven Results When Varnishing — how to deal with a newly-varnished painting that appears both glossy and dull
Problem: I applied two layers of Gamvar varnish 12 hours apart to my painting yesterday, applying thinly and working the varnish in – in accordance with the Gamvar guidelines. This morning I note that there are some areas of very high gloss and one small area that whilst not ‘matt’ is much less glossy than the overall mean. Is this variation of ‘reflection’ something to live with or should I apply more layers of varnish.
If the dull patches are over parts of the painting that were painted using burnt umber in the mixtures, that’s probably the cause of the problem. Burnt umber is highly absorbent after it’s dry. VE, 2018-03-30
See Removing Varnish
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.