Q:
I am applying GRP over a Polyurethane Foam, but it is very difficult. Bubbles keep forming and my brush and roller keep lifting the fibreglass off the foam - can you tell me why this is?

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A:
This has happened here because the foam should have been primed with resin first. By applying the laminate straight onto dry foam, the foam is very absorbant and has drawn resin out of the underside of the fibreglass and left a bubble.
Always prime foam with resin and allow to cure (it should seal the surface), this will prevent bubbles forming.
Our Tricast 2 foam is a little soft for flooring - Nidaplast would have made a more suitable core, but if there is sufficient fibre on top it should be ok.
Nidaplast Core - CFS