I have a plaster mold that I brushed polyurethane wood varnish onto in order to reinforce/seal it. I'm not sure if it worked, but I went ahead and poured some polyester resin inside anyway (Castin' Craft). Now that the resin is almost done curing, I'm wondering how I can get it out of the mold. I was thinking that I could thicken the resin a little more and then try to pry or break the plaster mold to retrieve the resin. Any thoughts?