Someone returned a canvas this week... it was a bit loose and floppy once it was unwrapped. We of course took it back and gave her a new one. This can happen to a canvas for any number of reasons and it is a common problem. I would like to share a tip. I took that canvas down into my workroom and I evenly sprayed the back with some water. Then I carried it back upstairs. By the time I got there it was already tight as a drum and as good as new!
That is usually an easy fix. There is a bigger problem that is not an easy fix. Whenever you buy a canvas you should check to make sure it is square.
Measure from the top left to the bottom right and then the top right and to the bottom left and the distance should be the same. If not, it is out of square and when you go to put it into a frame there will be trouble!! If you take the time to check this before you create a masterpiece it will save you a lot of headaches!