Your solvent is fine and any solvent that actually melts the plastic is ok.
Your warping is due to you only having two laminations. Ideally you should have a third internal or rear lamination which acts as a balancer and prevents the warp occurring.
Your warping is due to you only having two laminations. Ideally you should have a third internal or rear lamination which acts as a balancer and prevents the warp occurring.

