gelcoat
Gelcoat is a specialized exterior surface layer used on fiber-reinforced polymer parts, most commonly in marine and automotive composites. It provides a smooth, glossy finish, introduces color, and acts as a protective barrier against water, UV light, and weathering. Most gelcoats are based on unsaturated polyester resin or vinyl ester, with epoxy variants used for high-performance applications. The layer is pigmented to supply color and UV stability and is formulated to cure to a hard, abrasion-resistant skin that is thinner than the structural laminate beneath.
In production, gelcoat is applied to a mold or tooling surface as the first step before lamination.
The outer gelcoat layer serves cosmetic and protective roles: it provides gloss and color, reduces water absorption,
Limitations include UV aging, chalking, cracking or crazing under flex or impact, and potential osmotic blistering