How to Stretch a Sagging Canvas Painting

When canvas was introduced as a medium for painting on, the ability to paint differently and especially the ability to transport and paint very large paintings all the sudden became possible.  In modern days, besides wonderful effects possible only on textured canvas, the ability to not have to pick out or purchase a frame is also a plus.

If you plan to hang a painting without a frame, here are some things to keep in mind.

Make sure edges of painting are staple-free.  Look for the term gallery-wrapped, which means the staples are on the back of the canvas.  Or, in some instances, the staples are hidden on the back for an even cleaner look.

Make sure the artist uses a high quality canvas and stretcher bars.  There are many cheap studio-quality materials available that are meant for students and are not archival.  The canvas is usually thinly woven with minimal primer and the frames are cheap, knotty wood that may warp or bend over time.  I only use the highest quality canvas, linen, and stretcher bars.  They cost me a ton of money.  But I feel confident these materials will provide the best experience, painting, and longevity.

Be aware of thickness.  If item you are looking at says gallery or museum-wrap, the stretcher bars are probably 1.5 to 2 inches deep.  I usually use a 3/4 to 7/8 inch thick stretcher bar.  The reason is that this thickness correlates well to the small and medium-size paintings I usually sell.  Also, it is still easy to find a frame with a 3/4 to 7/8-inch thick rabbet (another story for another post – stay tuned…) in case you decide to frame upon purchase or at a later date.

Now, if you have a problem with a sagging canvas, all is not lost.  Reasons a canvas may sag is that it was not probably stretched, or most likely, because canvas is cotton or linen and an organic matter like clothing, can get stretched out  due to not taking care in storage (like setting things on top of while its lying flat) and also changing temperatures and humidity/dryness levels.

One of the first things to look for are these little wedges that fit into the back corners of your painting.

wedges fit into corners of painting

wedges fit into corners of painting

If your painting did not come with these little wedges, you can purchase them at art supply.  Just tap them lightly with a small hammer going around to each corner, doing opposites first, like when changing a tire.
If you have a very small painting, like this one:

back of small canvas painting

back of small canvas painting

First of all, you shouldn’t have much problem with small paintings. It’s mainly medium to very large paintings with stretcher problems. But if the problem persists on a small painting with no spacer wedges for stretching, there is a product one can apply to the back of the canvas called Tight’N'Up. It shrinks the canvas a bit making the canvas fit tighter on its stretcher bar frame.

If these options are not enough, the last thing one can do is have their canvas restretched. I recommend having it done professionally. Ask your local frame shop for advice. Or if you purchased it from me, I’d be happy to restretch your painting. If you are handy, you could do it yourself with some tools like pliers and a staple gun. You may want to look on Youtube for a video on how to do this before attempting yourself.

With proper care, your painting should last a lifetime and hopefully many lifetimes.