I used vac-u-mount adhesive to mount a 24x36" poster to foam core. I gave the back of the poster a toothy surface by sanding horizontally and vertically as well as the foam core and it has some bubbles in it! I left it in the press for 5 minutes. I gave the poster 2 coats of spray in both directions. The back of the can says suitable for plastic. The customer has not yet come to pick it up. Is YES paste my only salvation at this point?