Might be a dumb question, but can you dissolve the foam with some solvent? I would try putting a little acetone on a small test area to see how it does. Make sure to have good ventilation and no open flames/sparks nearby if you decide to try this approach.
I spent most of my money on booze, broads and boats. The rest I wasted. - Elmore Leonard
I had always thought that there was nothing quite so sad as an abandoned boat.-Terry Hayes