Photopolymer plates warping
I've been doing some experiments with Toyobo KF95 photopolymer plates and seem to be getting new challenges. I made small 3" intaglio plates few weeks ago and now those are warped to U shape, which is almost impossible to use again for printmaking. I exposed and developed the plates according to the manufacturer specs. I used Charbonnel Aqua Wash inks and cleaned the plates with plain water. Plates have been stored loosely in dark place in normal room conditions.
Is it necessary to mount those plastic plates to some sort of rigid plate to prevent warping? If yes, what would be best adhesive for that?
Is there any other way to prevent the plates from warping?
The metal-backed KM-plates might be solution to this problem, but I'm bit afraid that I would destroy my guillotine paper cutter when cutting those.