Help! Please. Stretcher strips bowing.
 

I just stretched a canvas on 60" x 60" heavy duty strips. I thought I would get away without putting a bracer bar in it. Dumb, me! I applied the acryilic gesso and now the strips are bowing inward. What's the best way to fix this? Should I unstaple two sides and restaple? Seems like it would be too loose. I can't think of any other way. Help, please.

No shortcuts!
 

Kimber, I would steer away from trying shortcuts because chances are they won't work. You need to take the canvas completely off the stretchers, and add extra support bars in the back. I usually add one in the center of the long side, but your sides are equal.

Does anyone have a suggestion for this? Should she use 45 degree angles?

The sooner you remove the canvas the better because once you apply gesso the edges don't ever quite flatten out.

Apparently what happens here is the shrinking effect by the drying canvas. We cannot proceed on by just adding new fixtures to straighten it. Doing that will create more stress on the fabric when paints are being plied onto it, and more shrinking with the paint drying on its surface.

I second Alex's wise advice to remove the canvas completely. In fact, this advice is useful in any situation where you experience bending/warping of stretchers.

Canvas should be streched drum tight only after completely primed and dry.

Recently, Mr. Whitaker emailed me about the subject and gave me the following tips:

• 1. Wrap your linen around your stretcher bars - not too tight - and staple the linen to the bars, about every four inches or so. This is temporary!

• 2. Brush on a coat of acrylic medium - whatever brand you prefer - Winsor&Newton or whatever.

• 3. After that clear coat dries, sand it lightly with fine sandpaper.

• 4. Doesn't hurt to brush on a second coat, and sand again, but not absolutely necessary to apply two coats.

• 5. Brush on two or three coats of acrylic gesso - thinned to the consistency of milk or cream. Sand between coats.

• 6. Notice that traditional canvases primed with flake white are relatively smooth - not too much weave showing. You want to fill your canvas with enough gesso coats to fill a lot of the canvas weave. Do this to personal taste.

• 7. When the canvas is dry, restretch it drum tight. Some folks play a hand-held hair dryer on the back of the canvas while they stretch. A canvas stretched dry will keep from getting slack much better than a canvas full of humidity.

Hope it helps.

Thank you, all, very much. I won't be back to the studio until Monday. I'm hoping my stretchers haven't popped by then! I stretched the canvas only finger-tight. Lately they seem to have been coming out too loose, so, maybe, I over-compensated on this one. Augh!

When I left the studio the fist coat of gesso was almost dry and the stretchers had bowed in about a quarter-inch, at most, at the center of two sides and a little less than that on the other two. On Monday, I'll unstaple it and then re-stretch it, as suggested. I will let you know whether, or not, the operation was successful.

You know when I read, or otherwise learn, about how to do something, somehow the warnings don't really sink in until I encounter the problems myself. And, so, now I know... long stretcher strips really do need bracer bars. I don't know why I'm so hard-headed.

I only stretch pre-primed canvas. I'd be afraid to prime after stretching. And I'm lazy. But it looks to me like Claudemir's post of Mr. Whitaker's method would work just fine.

I get uneasy when I have an unbraced length of more than about 18-20 inches. Crossbars are cheap insurance. Beats restretching.

Best-TE