Cutting corners -stretching canvas.

[Justintime]

Someone asked a while ago about trimming corners of a stretched canvas. Here's why not. The artist bought a cheap mass produced artist's canvas. When I went to tighten it, a stretcher bar broke so I'm restretching it onto nice new bars. But there's nothing left to wrap around the corners. As a result, a tray frame is not an option.

[JFeig]

The photo of your project is a new one for me.
I would gather that the notch in the canvas was made via a 100% automated machine assembly machine that does not allow for any post assembly modifications to achieve the lowest possible price. That includes using the keys of the bars for tensioning.
The client of yours when they purchased that stretched canvas got what they paid for, a modern disposable piece of crap, product.

Over the years I have trimmed excess canvas from corners to reduce bulk; but, never beyond the point if not having the ability to cover the height of the corner of the stretcher bars. The trimming was always done after the edges of the canvas was attached to the wood stretchers/strainers.

[Justintime]

Yes Jerome, you're right on almost all counts. It was the artist who bought the piece of crap and sadly I'm the client who bought the painting on it at an online charity auction, so at least it was a good price and I love the painting, but as the re-framer it stings a bit. As bad, is that the canvas is of such poor quality that it is barely holding up to stapling and it definitely won't withstand any tensioning... Any future work will no doubt require lining onto a canvas backing.