Even after carefully storing your photpolymer plates, you still get a few that stiffen up and curl on you. The solution to this is to dampen a paper towel and place it in a zip lock bag with the photopolymer plate that needs to be flatened. Leave the plate and the paper towel in the sealed zip lock for approx 20-30 mins. If you leave it in too long, it will start to curl the other way. If that happens, simply take the photopolymer out of the plastic bag and let sit out for a bit.