A little experiment I done a few weeks ago on a piece of polystyrene that had been painted with masonry paint to protect it from the polyester resin. Partly coated with a couple layers of CSM & polyester resin.

The first thing I noticed was how poor the bond was of the glass to the foam, which really shouldn't have been a surprise since it was only a layer of paint sealing the polystyrene.

Anyway I will let the video show the results..