Sand it with about 150 grit paper, to eliminate the impasto surface, wipe it off with a rag dampened with Odorless mineral spirits, and apply a couple of coats of White Lead Oil Paint over it, thinned with Linseed Oil and OMS.

For faster drying, substitute Turpentine for OMS.

That becomes your new, fresh surface, upon which to draw and paint.

Why White Lead Oil Paint? Why not Zinc White or Titanium White, or perhaps traditional gesso? Not challenging your suggestion; just curious.
Thanks!
troutbum

Acrylic “Gesso” (really “primer”) should not be applied on top of oil paint. Very likely to crack and/or delaminate. That concept is rather a “given”, I thought.

Zinc cracks.

Titanium is OK, but the ultimate in optimum surfaces upon which to apply “image paint” is Lead White. It dries fast, it is sound, in terms of archival integrity, and the surface it creates is quite wonderful for applying further paint. That’s one reason you hear so much about “Lead White Oil Primer”.

But, those are only my suggestions to the original poster. You may recommend anything you wish.:D

However, with the ridiculous prices being asked for Lead Carbonate White lately, I’ve actually been going with Titanium White. I refuse to use Zinc White, and acrylic primer applied over oil paint is out of the question.

Again I am not saying that there is anything wrong with your suggestions. I am just trying to learn by understanding the reasoning behind your suggestion. When I referred to traditional gesso, I was not referring to the acrylic gesso that must people use today; I understand why that would not work. I was however referring to “true gesso” which is not an acrylic based product.
troutbum

Why White Lead Oil Paint? Why not Zinc White or Titanium White, or perhaps traditional gesso? Not challenging your suggestion; just curious.
Thanks!
troutbum

Personally, I use Titanium White. The reason, is that it has covering power 10 times better than modern, weak Lead White, and 20 times better than gesso. Therefore, you can use a very thin, even molecular layer of paint to prepare white colored surface. Thin layer has an advantage, it do not affect painting, it do not shrink and do not increase total thickness of all paint layers.
Do you know, how much time needs to dry Lead White gesso properly? One year or more! Check any old manuscripts and you can read there that main trouble of Lead White oil gesso is cracking. Non-dried Lead primer cracks significantly. Therefore, ultra thin titanium white barier layer is better. It do not makes internal stresses.

Old painting has good enough layer of gesso, also well-dried oil paint on top of it. Sand it with sand paper and polish with pumice. Rub a couch of your regular medium to the surface. Wipe residue oil with paper towel, rub there a couch of most opaque Titanium White you have and let it dry two weeks. I use this method many times without any visible troubles. But this method works only for reused paintings and to re-paint a part of old painting. To prepare fresh canvas, use “traditional” acrylic or oil primers and standard recommendations.

I frequently reuse old canvases. I give them bit of a sand and a clean?wipe down then prime with Oil Prime. I think its Winsor and Newton, lovely to paint on. I also prime most my new canvases with the oil prime too.