**Authentically Human! Not Written by AI**
Okay, let's assume you've varnished your painting. (And if it's good enough to frame, why wouldn't you varnish it? Here's a post on that.) But after having had the painting lying about in your studio for awhile, you suddenly realize that the painting needs another lick or two with the brush in order to reach perfection.
You wonder: Should you just go ahead and get out the paint, or should you remove the varnish first?
The problem with painting on top of varnish is that varnish, unlike oil paint, is not meant to be permanent. Somewhere, years down the road, a conservator or restorer may find the need to remove the varnish in order to clean or touch-up the painting. If you've painted on top of the varnish, that extra paint will be removed along with the varnish. I know sometimes we forget to sign our paintings, but it's best if you don't sign them after varnishing!
You must remove the varnish first. And you must remove it from everywhere on the painting—not just where you want to place your signature or repaint an area. To not remove all the varnish will result in an unpleasant patchiness. I tried that once, and I ended up having to go back a step and remove all the varnish properly, re-sign the painting, and then re-varnish it.
To remove varnish, you need to know what type of varnish it is so you can determine what solvent to use. Is it an acrylic resin varnish or a natural resin varnish? Damar resin, which you find in a natural resin varnish, will not dissolve in mineral spirits; for this, you need turpentine or a citrus solvent. An acrylic varnish, on the other hand, can be removed with either mineral spirits or turpentine or a citrus solvent.
I varnish my oil painting with Gamblin's Gamvar, and if I need to remove the varnish, I use Gamsol with a soft, lint-free cloth. I dampen the cloth repeatedly with Gamsol (wearing nitrile gloves, of course, and with good ventilation) and, using a gentle, circular motion, go over the whole canvas. I can tell the varnish is gone because I typically use a gloss varnish, and when the Gamsol dries, the surface of the painting has a dull, matte look. Once it dries, I can repaint (or sign) as needed.
By the way, it's not too late to get into my one-day, studio-only workshop at Art Fest in Mesa, Arizona. The workshop is THIS THURSDAY, October 26th! in it, we'll take plein air references and learn how to create finished studio paintings from them. You can get $20 off if you use the coupon code SAVEONMF. You can learn more and sign up here.
