What is the purpose of a barrier coat in tooling applications?

Barrier coats, typically vinyl ester based, are applied between the tooling gel coat and the laminate. Their primary function is to block fiber print-through and reduce surface distortion in the finished mold.

Barrier coats also reinforce the gel coat layer and provide visual contrast that helps identify air entrapment during lamination. They are applied similarly to gel coat and laminated within a controlled time window for proper bonding.