Sanding and re-gessoing a large canvas: advice, tips and tricks?
March 7, 2010 9:35 AM   Subscribe

Sanding and re-gessoing a large canvas: advice, tips and tricks?

A couple of days ago, I came across a 5' x 4' stretched and framed canvas in a dumpster. Jackpot! The problem is all the thick impasto acrylic I'll need to get off before it's usable again. Does anyone have any tips or tricks on the best way to get this canvas in shape for re-gessoing? I'm assuming sanding is my best option, but I've never done anything on this scale that's marred by this much crud and was wondering if anyone has any recommended materials or advice. Thanks!
posted by aquafortis to Media & Arts (9 answers total) 1 user marked this as a favorite
If you're going to go through all the effort to sand and re-gesso, you should really consider just removing the existing canvas and stapling on new stuff. It's not too hard, especially if you have a canvas pliers. The time you save over sanding and re-gessoing is probably worth it, and artist's canvas, at least where I am, is around $5/yard.
posted by fake at 9:46 AM on March 7, 2010

I wouldn't bother with sanding and re priming it. My experience of sanding something, especially when it's this size is that you'll distort the weave on the canvas. This can be a real pain as you may well end up with lumps in the painting. The amount of effort that it will take to sand it down is comparable to the amount of effort it will take to rip the canvas off and re-stretch it. Also the material cost of the canvas is probably swallowed by the extra gesso and sandpaper you'll get through. Plus you'll be sure of a more consistent finish.

The other thing to bear in mind is you can rarely be entirely sure what the medium was that was used on the original piece. If it is entirely acrylic then it should be fine. But if there's any oil paint, turps or alkyd you can get real problems with the prime not taking, or cracking prematurely in certain areas or the old stuff bleeding through.

So I'd definitely re-stretch, you'll need some linen or cotton canvas. A staple gun and about an hour's work. I don't find that stretching pliers are necessary as long as you take care and make sure to put your first staples in at opposite points and take up the tension on the surface gradually. The smartest way to fold the corners with an origami fold to leave the seam parallel to the stretcher corner. There's a photo guide here (at the bottom of the first page and then onto page two).

Much of this advice is from bitter art school experience trying to skimp to get things done more quickly or cheaply, and in the long run it was neither quicker nor cheaper. Finally if you're going to invest time and love into a painting the worst thing is that it disintegrates because you didn't take some simple steps.
posted by multivalent at 9:54 AM on March 7, 2010

The above info is great. Also it might be fun to paint over the texture.
posted by snowjoe at 9:59 AM on March 7, 2010

Just for fun you could consider painting right over what is there. I have done that with success--the bad painting serves as an interesting ground. it's great practice and you might be surprised at the outcome. I have painted oil over the acrylic and it works out well. You could not do it the other way around (acrylic over oil)--but give it a shot before you dismantle it. I have a few step by steps on my blog of going over an old painting. I'll message you.
posted by naplesyellow at 9:59 AM on March 7, 2010

If you insist on having a perfectly flat surface, Fake has the best answer. The time invested in sanding-away the acrylic impasto would be best served just stretching a new canvas.

On the other hand, gessoing over the existing impasto and painting over it will, in my opinion, impart an interesting level of texture and presence to your work, as the impasto will almost certainly not follow your new paint. I've done this on my own canvases, and have really liked the results. It's sort of like having an untold story lying just beneath the new story you're telling. You could also let some of the old painting peek through.
posted by Thorzdad at 10:06 AM on March 7, 2010

This is a pretty reasonable video of someone stretching canvas. As others said, you don't need pliers; just pull it tight and a coat of gesso will make it seem even tighter when it's dry.
posted by bonobothegreat at 10:15 AM on March 7, 2010

I should also add that, if going the sanding route, you would almost certainly need to use a power sander to remove heavy acrylic impasto from the old canvas. That stuff is tough as nails. You stand a very real probability of tearing the canvas. You might want to try cutting the larger areas away, using a razor or box knife.
posted by Thorzdad at 10:17 AM on March 7, 2010

I've never removed the existing materials when I've reused a canvas. But, here's what I would do if I was in your shoes. I would go to the hardware store and get the least aggressive paint remover they have and a cheap, throw-away plastic putting knife. I would follow directions in the most gentle manner and see what happens. You should be able to remove almost all of the existing material without harming the canvas. At worst, you have a nice stretcher for new canvas. At best, you appy a new coat of gesso and voila!
posted by Old Geezer at 12:19 PM on March 7, 2010

A lot of paints are not so great to be grinding into powder that might find its way into your lungs.

Canvas is cheap. Cancer is not.
posted by Sys Rq at 1:48 PM on March 7, 2010 [1 favorite]

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