problem with loose large canvas

production · Post by **production** » Mon 10 Mar, 2008 8:47 pm

we have a large (80X62) painting on canvas. we stretched it and it began sagging. we sprayed the back of it, it tightened for a while, but then became loose again. is there any other trick that anyone knows of that will tighten a large oil painting on canvas?
thanks so much!

osgood · Post by **osgood** » Mon 10 Mar, 2008 9:04 pm

Are there cross braces in the stretcher?

Some 'canvas' will stretch and you might have to re-stretch it. If it happens again after the second stretching, it might be poor quality canvas!

production · Post by **production** » Mon 10 Mar, 2008 10:06 pm

we have braces in the four corners but not cross braces.

osgood · Post by **osgood** » Mon 10 Mar, 2008 10:22 pm

I'm assuming the size you stated is inches!
For that size, I would have cross braces in the centre, in both directions so that the bars don't bend inwards with the tension of the canvas!

CanvasChris · Post by **CanvasChris** » Tue 11 Mar, 2008 12:07 am

What size is the profile of the stretcher bars?

If your measurements are in inches, it's a big one!! then it does sound like bracing is the missing link. At that size it should be braced both ways and probably twice for the longer side.

However if your measurements are in cms then it shouldn't need bracing unless your profiles are the thinner ones.

More info please....

fionnuala · Post by **fionnuala** » Tue 11 Mar, 2008 1:17 pm

what are these cross braces ye are talking about?

are they wooden supports that u make yourself and attach to the middle of the stretcher bars to support them?

or are they something that you buy?

CanvasChris · Post by **CanvasChris** » Tue 11 Mar, 2008 1:21 pm

Cross braces are pieces of wood that support the bars and stop them bending under pressure of the stretch.

The bars should have cut out notches to accommodate them.

Have you a Lion Catalogue.... if so look on page 80 for a picture showing the braces on a frame.

Are your measurements in inches??

JFeig · Post by **JFeig** » Tue 11 Mar, 2008 1:39 pm

production wrote:we have braces in the four corners but not cross braces.

This sounds like you stretched this large canvas on strainer bars and not "stretcher bars". Stretcher bars allow to tension adjustment, strainer bars di not. I also agree that internal cross bracing is another problem.

fionnuala · Post by **fionnuala** » Tue 11 Mar, 2008 1:41 pm

yup. get it now. thanks. lion seems to have everything!!!

CanvasChris · Post by **CanvasChris** » Tue 11 Mar, 2008 1:42 pm

They do!!!!

Nice bars too... if a tad expensive. Although not as expensive as the ones I use...ouch!!!!

JFeig · Post by **JFeig** » Tue 11 Mar, 2008 1:46 pm

I have one more thought, Mobile, Al is right on the Gulf of Mexico .... a very humid area. When Summer comes, it will loosen up even more.

BTY, my largest stretching job was 20 ft long and 10 ft high.

JFeig · Post by **JFeig** » Tue 11 Mar, 2008 1:52 pm

For those on the east side of the pond, this is a source I have used. http://www.ucsart.com/

Do to you chaps have a similar source.

CanvasChris · Post by **CanvasChris** » Tue 11 Mar, 2008 2:01 pm

Nice looking bars....

It's a shame once a canvas is wrapped, stretched, and taped and hung that the frame is not seen.

The customer doesn't perceive that fact that being made from a very high quality timber and won't warp costs!!

Some online retailers sell canvas prints for less than I make them for!!

Framer Dave · Post by **Framer Dave** » Sun 16 Mar, 2008 2:31 am

production wrote:we have a large (80X62) painting on canvas. we stretched it and it began sagging. we sprayed the back of it, it tightened for a while, but then became loose again. is there any other trick that anyone knows of that will tighten a large oil painting on canvas?
thanks so much!

Oh my, I just noticed you're in Mobile. Being in Houston, I feel your pain.

First, make sure your stretcher bars are sturdy enough for the size of the canvas, and make sure they're cross-braced as everyone has suggested.

Second, what was the weather like when you first stretched it? If it was one of those rare dry periods when you did so, the canvas was probably fairly dry and thus naturally taut. So you didn't have to put a lot of tension on it. Then when the weather turned humid again the canvas relaxed and started to sag.

The opposite can happen if you stretch a canvas in very humid weather. You'll have to put a large amount of tension on it to get it in plane. When the weather dries and the humidity drops, the canvas will contract, putting too much tension on the canvas, possibly causing it to tear along the tacking edge or in an extreme case, cause paint to crack and flake.

When you stretch it again try to do it in the middle of a humidity cycle.

Post by **prospero** » Sun 16 Mar, 2008 3:46 am

I just had a weird one.

I went over to take some paintings to a gallery I deal with and on the wall was an oil I framed last year. (36x24). It was perfectly fine when I framed it and it was with me for about a month. But while it was on the gallery wall it had gone all bumpy and generally flappy. The stretchers had no wedges, so I thought OK, it needs tightening a tad, so I bought it back with me and tapped a few wedges in. This got rid of the flap, but it was still badly puckered along the top edge. I took it off the stretchers and tried remounting it in the time-honoured way, but no way would it lay flat. Even a bit of strategic damping didn't work. Never seen the like.

I originally thought it was a good quality fine linen canvas, but when I unmounted it I could see an umprimed piece on the edge that revealed it was very thin cotton. The back of the canvas had gone brown, which what made me think in was linen. Normally, canvases are flexible and supple. Not this one. It feels like a dried up leaf.
I advised the gallery owner to have it relined on a stronger canvas. I don't really want to frig around with it too much as I don't think it would take much to tear it.
Pity really. It's a beautiful painting. Just wish some artists wouldn't try to economise with their materials.

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