In our experience, in-mould polyester gelcoats have yielded better results than epoxy gelcoats for exterior finish applications. But which type of gelcoat is best for each application?
We have had good results with various in-mould polyester gelcoats. Because of their superior resistance to ultraviolet degradation, polyester gelcoats are preferred over epoxy gelcoats for exterior finish applications. Check with your polyester gelcoat supplier for recommendations and test to determine product suitability and application technique.
Some fabricators have reported good success using a 2-part linear polyurethane paint sprayed directly onto the mould surface. This coating is allowed to cure and the epoxy laminate is applied directly to the paint. An epoxy gelcoat is sometimes preferred for plugs and moulds.