Skewed canvas

[Starboard]

Hello, Community,

I am a new framer.

My wife is a painter. She had a commission for a triptych, which she duly produced on three BestofHobbycraft or suchlike brand 2x3 canvases. She then showed some black L frames samples to the client who chose a simple one.

Turns out these canvases are really skewed, in the tune of 12mm over the height - see picture.

Screenshot 2025-10-04 at 10.54.50.jpg

I can't put them in an L tray type moulding without it seriously showing out of kilter. I am not too keen to take the canvases away and put them on new stretcher.

What would you do?

First idea is to find a simple black moulding with a deep rebate so i can position the canvas and hide the skew, but it is hard to compensate for 12 mm

Or would you try to use a L tray moulding "in reverse", that is by putting the tray "over the canvas" rather than under?

Any other solution?

Big thank you.

[JFeig]

The attachment image doesn't tell the reader anything. Only one edge is shown.
Some basics of geometry first.
Do you have a carpenters square or a T-square and did you use it when you assembled the stretcher? the edge of a square table would also work? An alternative method is to measure the 2 diagonals so that they measure the same.
Are you using adjustable stretcher bars or are you using simple mitered timber?
Did you measure the lengths to determine if the apposing rails are the same length?

If the out of square is due to the actual bars not the same length or if they were assembled out-of-square you have to take everything apart and start over remaking the stretcher system.
If you used adjustable stretcher bars you can take off the canvas, square the stretcher and then reattach the canvas using the same stretcher system.

Then there is the question of is the painted subject square? If not, you have to do the best you can to capture as much as you can with a "square" stretcher. If the canvas was cut to size (without margins) and you have a predetermined size to produce, the artist might have to redo the entire painting by first measuring out the dimensions on a larger canvas and then measuring to make sure that the area to be painted is square.

[Fruitini]

Hi. Always annoying when that happens. Cheap canvases are a false economy! Simplest solution is to take the canvas off the stretcher, square up the stretcher and staple the canvas back on as central as possible. It’s likely you’ll get a couple of edges where the unpainted sides of the canvas now show slightly on the front, and conversely on the other edges the painted face of the canvas now shows slightly on the edges. You said your wife is the artist so should be relatively straightforward for her to touch up the unsightly edges! Problem solved!

[JKX]

Prevention is better than cure and a ‘L’ square is a handy thing, but if buying pre-stretched canvas it’s best to take it to the shop with you!

If you’d rather not remove the canvas and square the stretcher up, a flat slip inside the frame would work but you’d have to mount the canvas skew-whiff which could mess up a horizon etc.

[Gillthepainter]

As you are a framer, I would take the canvas off the wonky stretchers. In your image it looks like you have bowing, rather than skewing.

I'd make new stretchers that are true.
You can resize the paintings any size you want after all, which can fit your drop L frames.

So if eg the wonky canvases are 16" x 12", take the pic off and make a stetcher 15.5 x 11.5, to compensate for the distortion = keeping as much of your painting as possible.
If I make a stretcher, I either mitre an existing large one, or cut pine to size, and put a d-trim on the outer edge to raise the canvas proud of the wood.
However, as the paintings are already painting by your OH, you can just cut a flat pine stretcher, as you are not going to get painting tram lines on the front from sharp wooden edge.

All this is fairly easy to do.
Except you have to be careful of a hobbycraft canvas. Stretch it gently with your hands rather than artist pliers, as it may rip easier than you imagine.

[Justintime]

If you don't set some boundaries early on then these issues will continue to arise between you and your wife. As has been said, buying cheap canvases is a false economy but she is also expecting you to perform miracles with sub standard materials. Simply put, work out the additional labour and materials cost of adding a slip to the frame this time and request that she spends that much more on a higher quality canvas in future!
I speak from experience.

[Starboard]

Thanks.

I did not assemble the stretcher and yes, I checked the geometry of the canvases with a T Square but only after they were painted, a bit late into the play.

What you see on the picture is a 10mm gap what placing the canvas on a black background (a glass table which is indeed square) one edge aligned, lowest part of the bottom aligned, to illustrate the deviation.

I appreciate the fact that buying cheap canvases is a false economy. Will tell my wife to steer clear of these in the future. Good pointer. also, going to the shop with your T-square is a great idea.

I could indeed make a new stretcher – never done one before, I am very new to the game – but as Gillthepainter notes, this is also BestOfHobbyCraft material and I have no confidence it is going to survive the restreching well, so i'd rather deal with one issue at the time

So, not ideal, but the slip solution sound the most direct route.

Thank you for your help.

[Gillthepainter]

To be fair to your wife, Hobbycraft aren't that crappy. There are worse shops.
But you do have to inspect the merch. before you buy. It is in cellophane, so takes a bit of effort. And those 3 for 2 deals can be tempting.

You can get skewed canvases at the best places. But now she knows to have a real good look.