I'm a newbie at this. In gluing the puzzle pieces some light plastic (my cheap drop cloth!) got epoxied on to the reverse (the outside hull) side. I want to clean it off without wrecking the panels. The plastic is very thin and I have been able to peel off most of it, but there is still some left and scraping doesn't touch it. Is sanding the best option? Any suggestions from this august group will be appreciated.