OK, is it just me, or do the pre-made medium stretcher bars always seem to warp? I have had bad luck in the last couple of years with fairly large canvases that I stretch and prime looking really wonky when they go up on the wall. We’re talking about maybe 1/2 inch or so out of square- but I can see it. Then sometimes the dang thing is even bowed in or out on one edge. This never used to happen to me- and I suspect the wood is inferior, unseasoned, whatever.
Now, only the heavier ones will do, I suppose, or I will try painting on wood panels instead. I used to love working on masonite and wood.