Stretching a canvas means pulling a loose piece of fabric over a wooden frame and fixing it there at an even tension, working from the centre of each side outward. VanArtHub does this by hand at 1242 Davie Street in Vancouver, on bars cut to the individual piece. The order the staples go in matters more than the force used, because an uneven pull shows in the finished surface and cannot be corrected once the paint has settled.
What the job actually involves
A stretched canvas is three things: the fabric, the wooden frame underneath it, and the tension holding one against the other. Get the third one wrong and the first two stop working. Too loose and the surface ripples in raking light. Too tight and the corners pull, the weave distorts, and on an older painting the paint layer can crack along the lines of stress.
The frame is called a stretcher when it has keys in the corners and a strainer when it does not. The difference matters: a strainer is fixed at the size it was built, so when the fabric relaxes there is nothing you can do about it. A stretcher can be pushed very slightly wider later. Almost everything we build is a stretcher, because fabric always relaxes eventually.
The order the staples go in
This is the part people get wrong. The fabric is centred over the bars, then the first staple goes into the middle of one long side. The second goes into the middle of the opposite side, pulling against the first. The third and fourth do the same for the two short sides. Only then does anyone work outward, always alternating, always in pairs, moving a few centimetres at a time toward the corners.
Stapling along one whole side first drags the weave crooked. The image ends up very slightly rotated relative to the frame, and the corners will never sit square no matter what is done afterwards. On a painting that has already dried, that distortion is permanent.
Corners
The corner fold is the tell of a careful job. The fabric is folded once, cleanly, so the bulk sits on the side of the bar rather than on the face, and the fold is consistent on all four corners. On a gallery wrap, where the sides stay visible, the corner is folded so the seam faces downward or toward the wall and reads as deliberate rather than as an accident.
How much tension is right
Enough that the surface reads flat and gives very slightly under a fingertip, and no more. A canvas is not a drum. On a new painting the aim is a surface that will still be flat in ten years, which usually means slightly less tension at the start than feels satisfying, because the fabric continues to tighten as it settles.
On an older painting the answer is different again, and it is the reason re-stretching is the more delicate of the two jobs. The paint has already dried in one position. Pulling it noticeably tighter than it was is how you introduce cracking. Anyone re-stretching an old canvas is aiming to restore the tension it had, not to improve on it.
What we need from you
The piece, and enough unpainted margin around the image for the fabric to wrap the bars and take staples. Four to five centimetres on every side is comfortable. Less than about two and a half becomes difficult, and a canvas trimmed right to the edge of the image cannot be stretched conventionally at all. If yours has already been trimmed close, bring it in before doing anything else, because there are ways to handle it and they all start with not cutting anything further.
Related
See stretcher bars explained for what sits underneath, why a canvas goes slack if yours has already softened, and canvas stretching in Vancouver to bring a piece in.
Common questions
Why do staples start in the middle of each side?
Because the fabric has to be pulled evenly against itself. The first staple goes into the centre of one long side, the second into the centre of the opposite side pulling against it, then the two short sides, and only then does anyone work outward in pairs. Stapling along one whole side first drags the weave crooked and rotates the image very slightly relative to the frame.
How tight should a stretched canvas be?
Flat, with a very slight give under a fingertip. A canvas is not a drum. On a new painting it is normal to finish slightly less tight than feels satisfying, because the fabric continues to tighten as it settles over the following months.
What is the difference between a stretcher and a strainer?
A stretcher has keys, the small wedges in the inside corners, so it can be pushed very slightly wider later to take up slack. A strainer is fixed at the size it was built, so when the fabric relaxes there is nothing to be done. Almost everything worth keeping is on a stretcher.
How much unpainted margin does a canvas need to be stretched?
Four to five centimetres on every side is comfortable, because that margin wraps the bars and takes the staples. Under about two and a half becomes difficult. A canvas trimmed right to the edge of the image cannot be stretched conventionally, so bring it in before cutting anything further.
Can an already painted canvas be stretched?
Yes, and most of what we stretch is already painted. The care needed goes up with the age of the paint, because a dried paint layer tolerates less movement than a fresh one. That is why re-stretching an old painting is slower work than stretching a new one.
Why does the corner fold matter?
It is the clearest sign of whether the job was done carefully. The fabric should be folded once, cleanly, with the bulk on the side of the bar rather than the face, and identically on all four corners. On a gallery wrap the fold is turned so the seam faces down or toward the wall.
Is stretching the same for oil and acrylic?
Mechanically yes. What changes is how much the surface tolerates being moved, which depends on how thick the paint is and how long ago it dried rather than on which medium it is. A thickly painted piece of either kind needs more care.
Do you stretch canvases people bring in?
Yes. Rolled canvases, loose canvases, and paintings that need lifting off tired bars and re-mounting. Bring it to the gallery at 1242 Davie Street in Vancouver and we will look at it with you. See canvas stretching in Vancouver.
