SO i've attached a few posters to the foam core arts n crafts style board to keep them from stretching out, and it worked for the first two i made. Then a year later i did two more, but the are starting to get ripples in them, where the poster seems to be "expanding" and pulling away from the board. The only thing i can think of is that the spray adhesive i used the second time wasn't as good as the first, even tho i used 3M, so i should have been fine. Anyone know of a way to remove the poster, like with a hair dryer or something so i can re glue it with better stuff? These are like 3foot by 4 foot posters btw.