03-01-2012, 07:24 AM
Greg, the backdrop is foamcore or foam board. The type with something like cardstock bonded to each side of a foam core. When I worked at the museum, we used this stuff by the case for mounting photos, text boards, etc. Its very light and easy to work with. But, like a lot of wood and wood fiber products, its prone to warping when you get it wet or damp, like painting, especially if you get it damp on one side. The solution is to dampen the opposite side and weight it down flat, which was what I did last night. This morning all the panels were again nice and flat, so they're going back up on the layout.