A dent in a stretched canvas is something that happens to most painters at one time or another; a finished painting or an unpainted canvas can be dented in storage or shipping. These dents look alarming but can be easily removed and the canvas will be completely back to normal.
Wet the back of the dent
Removing a canvas dent is a quick and simple process of wetting the back of the canvas just where the dent is. If the canvas is dented from the front to the back or the back to the front, the process is the same, you wet the canvas on the back. It works for unprimed, primed and painted canvas.
You can use tap water in a spray bottle or hot water from the tap. I have heard of people using steam from an iron or a kettle. They all work instantly to reshape the spot. My usual method is hot water from the tap, dribbled on the spot. I have never had a negative side effect from water, room temperature or hot. (See below for cautions if you have sized your canvas yourself with rabbit skin glue.)
The water will probably bead up a bit so you will need to give it a quick rub with your fingers to encourage it to soak into the weave. The dent should pop back right away. If you get too much water on the back it can run into the stretcher bars and wet stretcher bars can warp as they dry, so have a towel on hand to mop up any excess. You just need the water right on the back of the dent, not all over the canvas.
Beware of using water on rabbit skin glue sized canvas dents
If you have sized your canvas with rabbit skin glue then water on the back might soften the glue, as it will absorb the water. So don’t use hot water and use as little water as you can, being quite careful. But acrylic sized or primed canvases should all be fine and bounce back nicely.
A dent is not the same as a sagging corner
The dents I am referring to are pushed up dimples in the flat surface of a well-stretched canvas, not a loose area of the canvas. In addition to dents in canvas, many artists also use hot water to tighten up a sagging primed or painted canvas. But I have not found this to work as well. It appears to work for a few minutes and then the sag reappears by the next day. Sometimes it has shrunk a small amount, though usually not enough. If a canvas has not been stretched evenly or tightly enough, or has become loose over time, the best solution is to insert the wedges into the stretcher bars and push the bars apart slightly. If that isn’t enough, you will need to restretch your canvas. Do not judge if an unprimed canvas is too loose until after it has been primed as a primer can shrink the canvas by up to 10cm, and so any looseness may be solved. But if the canvas doesn’t have even tension, then it can tighten up everywhere but one or two corners and it may be that you will need to restretch it, maybe just removing staples from one corner and pulling it tighter there, but sometimes the whole canvas will need to be restretched.
Other articles about stretched canvas
- How to Stretch Canvas: a Visual Guide
- Choosing the Right Canvas for Your Painting
- Everything You Need to Know About Stretcher Bars
Stretched Canvas at Jackson’s
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