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cremo
03-26-2019, 03:39 AM
Just a quick question: I need to rework a painting, but this painting has been varnished previously with a final varnish.

Can I simply paint over it? thank you for the help!!!! :wave:

kentiessen
03-26-2019, 07:46 AM
All varnishes are designed to be removed without the process affecting the dried painting below. With Gamsol, the instruction is to wash with mineral spirits. I would recommend this varnish removal before adding new oil paint.

cremo
03-26-2019, 09:58 AM
thank you very much Ken !!!

koumk
03-26-2019, 10:09 AM
Yes you can

kentiessen
03-26-2019, 10:10 AM
You are welcome Gianluca!

cremo
03-26-2019, 10:26 AM
Yes you can

Do you mean to paint over a vernished coat?

kentiessen
03-26-2019, 11:13 AM
There is the possibility that in the future someone may clean the painting (remove and refresh the varnish). If you paint on top of varnish, it is possible that your added work on top of it would come off too.

Pinguino
03-26-2019, 11:16 AM
Difference between whether you "can" do it, and whether you "should" do it.

Will the re-worked painting be permanent, or is it only an exercise?

contumacious
03-26-2019, 12:16 PM
Already covered in bits and pieces above......I will attempt to bring them all together for you in one list plus maybe a bit more, though I may miss something. If this piece is quite valuable, you may want to seek professional advice.

Whether you can, should or should not just paint over it, depends on the type of varnish on the painting. Go slowly and test in a less conspicuous area if you can. You should not paint over removable varnish unless you don't care that your new upper layers might separate later from the older ones.

Unknown Varnish
Try to remove it first with Gamsol or some other mild OMS. If it comes off without removing more than trace of color, then you are good to go - remove it, then paint away.

If it doesn't come off, then it might be a resin based varnish like Damar Varnish. Try using artist quality turpentine. It is going to go slowly. If the varnish comes off without too much color, then remove it and paint when it is gone. There is a chance that turpentine will dissolve the paint layers as well as the varnish if you used resins in your mediums or if the resin based varnish cross linked with your paint. If too much paint is coming off with the varnish, then you may choose to paint over the varnish. Clean it off first with some OMS before you paint on top. Roughing up the sheen will help adhesion of the new paint.

If nothing comes off, it is probably some kind of permanent varnish. You can rough it up for better adhesion of the new paint with some pumice and OMS or a fine grit (800-1200 grit) sanding sponge. Clean off the sanding residue with a cloth and OMS and start painting.


Known - Removable
Follow the instructions of the varnish maker for removing it.

Known - Permanent
See the instructions of the varnish maker on how to paint over it. If it is shiny, even if the makers instructions don't mention it, you should knock down the shine with some kind of grit as mentioned above to give the new paint something to adhere to.

JCannon
03-26-2019, 03:07 PM
I had to do it all the time when I was an illustrator working in acrylics. Someone always orders last-minute changes.

That work was not meant to last the ages, of course. I can say only that the few works which remained in my possession seemed unchanged after a couple of decades.

If your varnish yellows, you (or your descendants, or whoever buys the picture a century from now) must live with the yellow. Only the uppermost layer of varnish can be removed and replaced.

For present purposes, the most interesting question is: What would happen to paint applied over the newer varnishes like Gamvar, which can be applied to work not fully dry, and which the maker insists stays "water clear"? Gamblin does not recommend painting over this varnish. But if you do it anyways, will the heavens fall?

I suspect that they won't.

WFMartin
03-27-2019, 01:16 PM
I believe that perhaps once, or twice I have painted a very tiny area with oil paint, over my varnished painting, out of desperation--such as when I forgot something rather important. I believe I have done it with a signature, a time or two. But, that's about it.

Of course, I did this fully realizing that if the varnish was to ever be removed,.....then so would my painting that was on top of the varnish be removed with it!!

That's the reason I've only done it out of desperation.:lol: It is NOT a practice that I would recommend to someone whom I consider to be a friend.:)