How much tension should be placed on the canvas when stretched over wood bars and is it necessary to secure the stretcher bars together prior to stretching the canvas?
My reason for asking is prompted by my method of stretching the canvas. I use a Fredrix style 22 cotton canvas that is unprimed at 7 oz. and primed at 11.5 oz. , plus an additional four coats of quality Gesso is applied to the stretched canvas.
Tightness of the canvas allows for a “hollow” sound when thumbing the face side and there is some slight tension pull shown at most staples.
Will the canvas tension impact the oils after several years?
Is it advisable to secure the corners of the stretching bars or let the canvas maintain a good corner square? I have personally seen both methods used and am concerned if there is an advantage over one method.
Patrick McGuire
Cotton canvas tends to “relax” to a point of maximum sustainable tension, so pulling beyond the capacity of the fabric doesn’t yield a sustained, drum-tight surface. Sizing and primer have an important role in stiffening the fabric, to maintain a flat plane after initial tightness has reduced. 7oz. cotton is really light fabric for stretched canvas, in my opinion- I always get better results with heavier fabric.
As you point out, inserting staples across the stretcher joints can help hold the chassis in square. Personally, I do this sometimes, but only on the back of the canvas- never under the fabric- and I always take them out after stretching is complete. Not only does it look un-craftsmanly to leave them in, the staples could mar a painted wall and interfere with keting out the painting, should it become loose.
Where technique is concerned, I’ve long been a proponent of stretching “on the bias”, diagonallly against the weave instead of pulling directly against warp and weft. I find that I can achieve a very tight stretch this way with minimal use of tacks, and since tension is spread over the entire weave network, bias-stretched canvases have less puckering and weave distortion.
Thanks Matthew, we were traveling all day today and it is great to have you fielding questions. Personally, when painting on cotton duck, I always preferred #10 or at least #12 weight for many reasons including planarity and longevity but also resistance to being puckered by the slightest pressure.
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