I have a 4' x 4' piece of plywood artwork (acrylic painting) that has become warped. It used to be mounted to drywall using velcro strips, but now the outward force of the warp is strong enough that "peels" off and cannot stay on the wall.
I've tried undoing the warp by wetting the concave side and flattening with weights, which only seems to work temporarily — the warp returns after a few days.
Is there a way to permanently undo the warp, so that the velcro mounting system is viable? Or is there another way to mount this that would be non-destructive to the art and reasonably portable?
One answer in Is there a way to remove the warp in plywood recommends nailing or screwing the plywood to something, but that sounds destructive and non-portable. (Another suggests leaving the plywood in the sun, but sadly I don't have a place to do that near my apartment.)