for my two cents, I used craft foamies (2 mm I believe, the thin stuff) to create my Batman Begins style gauntlets a few years ago, I used plastidip, but I brushed it on the foam straight away without sealing the foam, then painted it and had zero trouble with it ruining the foam. The only real issue is that plastidip is runny or has the tendency to create runs as most of us that have used it before can attest. In no way was the craft foam distorted.