UV Activated Resin. Work in the Shade or indoors, place in direct sun for fast almost instant setting.
You must determine which type of resin to use.
Most regular surfboards use Poly Urethane (PU) Foams, laminated with Polyester Resins.
Modern Expanded Poly Styrene (EPS) foams are laminated with Epoxy resins.
It's important to get it right because Polyester Resins will dissolve EPS foams.
These Resins contains Fibreglass fibers for strength when patching minor dings.