Saturday, March 22, 2014

Prep work

With a big pile of stretcher bars, it was time to get busy stretching. After stretching, each canvas gets two coats of Golden GAC 100, a multi-purpose acrylic polymer. In this case, its purpose is to isolate the canvas from the destructive qualities of the paint, which can really degrade canvas or linen over time. Over two coats of the polymer, I brush on three coats of Golden Gesso. The gesso is also acrylic based, so it bonds well with the the GAC 100, but it is porous as apposed to the shielding quality of the earlier layers, so the paint soaks in and binds to it.  A safe, secure, archival ground to build a painting on.  I can usually juggle 3 or four big canvases at a time, moving them around the studio, propped and drying, waiting for another layer. Each is dated after the last coat, so I know that it's dried sufficiently over a couple weeks to provide a dry and stable surface.


Virginia Wood said...

I read this with interest, as I am also an oil painter. I have always primed my canvases with gesso (Golden or Utrecht) to which I add gloss medium and water in the ratio of 2 parts gesso, one part medium and enough water to thin it into a proper paint. I usually do three applications sanding in between.

I hope to try your method at some question comes to mind. I sometimes remove my completed painting and roll it to the outside for shipping (I have done this a lot for dealers). Do the final layers of gesso (without the added medium) create a danger of cracking? Gesso is brittle, which is why I add the medium, and why I use the high quality gesso. If the ground cracks the painting cannot be repaired easily (if at all), and I had some older paintings I sized with gesso alone crack over time. They were not removed from the stretcher bars. It was the underlying ground that cracked.

Richard C. Harrington said...

HI Virginia,
I apologize for the delay- I missed the comment til now.

I ship larger paintings rolled, and haven't had a problem with cracking, at least not any more than I would expect. I roll them paint side out, over a large tube, in order to make the diameter as large as possible. I ship them in 10 in diameter Sonotubes- a tube made for pouring concrete footers. You can get them at lumber yards and cut them down with a hand saw.

The GAC 100 is, I believe, approx as flexible as gesso. It's function is primarily to isolate the canvas, so paint can't soak through the gesso and into the canvas. Golden makes several other polymers- GAC 200, etc- that add stiffness to the ground, which is not what I'm after.

Hope that helps.


Richard Harrington