Steve, There might be some solvent reaction between the petrobond ( alchol) and the enamel on your patterns which cause the sticking. I, also, use petrobond, and all of my patterns are coated with clear shelac then rubbed with 000 steel wool, then re-coated with krylon red primer. The patterns are re-rubbed with 000 steel wool again then used for casting. The "NEW" Krylon paint in the cans with a tapered cap are enamel. The "OLD' paint with the straight caps were laquer which worked very well, but not now. ART