Canvas priming and oil absorption

**Scale** · February 14th, 2013, 11:20 AM

So far I've been using a very basic way of priming stuff for oil painting depending on the support I use:

Canvas: I buy a premade canvas with minimal acrylic priming. I add 2-3 layers of acrylic gesso priming on top of it, sometimes mixed with an acrylic color to get a ground tone. Then I paint with oils directly over this priming.

Paper: I put the same priming as above on thick paper (like watercolor paper), but since I usually have a detailed drawing to work with I use the technique described by Gurney here:
http://gurneyjourney.blogspot.it/200...and-bolts.html
So basically I put a layer of acrylic matte medium on top of the gesso priming, and then paint with oils on top of the matte medium.

I don't mix any thinner with the paint, just a bit of walnut oil to get a gloss finish. This works well so far but I'm very confused on the topic of priming and oil absorption and I'd like to understand it better before trying more complex stuff:

- Some painters say that acrylic gesso is perfectly fine for priming, while others insist that any canvas should be primed with a layer of oil paint because the gesso is too much absorbing and painting directly over it makes the paintings prone to cracking and other flaws.
I assume this means the canvas should be treated first with a basic priming like gesso (or rabbit glue or similar stuff) and then with a first layer of thinned oil paint on top of gesso, letting it dry, then starting the actual painting on top of it.
I don't get how this is supposed to fix the issue of absorption though. Wouldn't gesso absorb oil from this first layer? Wouldn't oil from the top layers trickle all the way down to the gesso layer anyway? Or maybe this first "lean" layer forms a barrier and prevents oil from the topmost layers from reaching down to the gesso?

- Some painters also told me that oil paint can be used directly for priming raw linen, but this sounds very suspicious. I thought that oil soaking the raw tissue is right what priming is supposed to prevent, right?

- I know premade canvases are considered bad, but why exactly? Is it just because they come with a poor quality priming? Can they be improved by adding a proper priming on top of it?

Thank you for any answers!

**Stoat** · February 14th, 2013, 12:02 PM

The traditional support is rabbitskin glue against the canvas (to protect it from the corrosive effects of linseed oil), THEN a couple of layers of oil paint.

The objection to acrylic gesso is that it defies the fat-over-lean rule -- that is, you never put something less flexible on top of something more flexible, because when the bottom thing flexes, the top thing cracks. Acrylic being more flexible than oil, supposedly.

I used to care about painting for permanence quite a lot, but that was back before digital. Now I figure once it's digitized, it's immortal.

**QueenGwenevere** · February 14th, 2013, 12:22 PM

For what it's worth, I've got plenty of oil-over-acrylic paintings that have been around for decades and none of them have had any problems whatsoever... Will there be issues in a few hundred years? I don't know, and I honestly don't much care, any painting that sticks around for that long is going to need some kind of cleaning and restoration regardless and I'll be dead anyway.

I don't know why people would object to pre-stretched canvases. I suppose it might be because some are kind of cheap in quality. But these days you can get a whole huge range of quality, and the better varieties should be perfectly fine. Just avoid the cheapest student grades. And if the priming is inadequate, just slap on another coat or two, no big deal. (Also if you have a shop near you that does custom stretching, you can even get "artisanal" hand-stretched canvases, or custom-stretched canvases, which is no different than doing it yourself except you don't have to do it yourself.)

**Craig D** · February 14th, 2013, 03:41 PM

If you really want to use rabbit skin glue remember that it can only be used with a rigid support. On just canvas it will crack, it needs to be mounted on a rigid surface.

Linseed oil is corrosive to organic fabrics (canvas, linen, paper etc.) and must be protected by an isolating layer, called a size. So sizing canvas is putting down an isolating layer between the paint and your support. Traditionally that was rabbit skin glue but you can get more modern alternatives such as acrylic media.

Primers (Grounds) such as oil primer, traditional gesso or acrylic gesso are there to provide a first coat for the paint to adhere to and to regulate absorbancy and texture. Oil primers will let your paint bond both chemically and physically while acrylic gessos probably only provide a physical bond. Seems to be more than strong enough to last for at least a few hundred years though.