How to fix a canvas with a warped corner
Reader Question: I have a 48" x 60" gallery wrapped canvas that has one corner that is warped. It will not hang flat against the wall when I am done with the intended artwork (a head, shoulder & chest of Champion Boxer Joe Louis -- with gloves up!). I will be using Acrylic paint. I keep reading that I should spray the back of the canvas with water or use "Tighten-Up" if water doesn't do the trick. I know nothing about trying to take the canvas staples lose and re-stapling. I looked for videos to show me the spraying technique, but found none. My question: Is water spraying a true solution and how long is drying time? Thank you in advance.
Based on your description of the canvas not hanging flat against the wall, I wonder whether the problem is with the canvas itself or instead, with the stretcher bars. In my experience, if a painting doesn't hang flat against the wall, it usually means the stretcher bars are somehow out of alignment. If that is the case, try to identify which corner isn't hanging flat against the wall and check if the stretcher bars are warped or bent. You may be able to use a hammer and bang it back into place, so that it lines up evenly with the stretcher bars that are straight.
Now, if the canvas itself is warped (that is, dented or wobbly-looking), then you can use water or Tight'N'Up (this links to Blick Art Materials, and if you make a purchase I get a small commission that helps support this site). I have used the water-spraying trick on several occasions to successfully even out any dents or wobbles in the canvas. The water doesn't take too long to dry - depending on how much water you spray, perhaps 30 minutes or less? If the water doesn't work, then a product like Tight'N'Up may do a better job (but as I said, water has always done the trick for me).
I hope that helps!