You would need to key the PU for the EF80 to get a mechanical grip.  The bond between the two materials will not be very strong so it is possible the EF80 may peel eventually off the surface.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

I have a skin on frame kayak currently with polyurethane coating sealing a nylon skin.
I need to apply an additional coat to fill the weave but have no more polyurethane.
Will EF80 adhere to the polyurethane?