Epoxy resins incorporate epoxides—remarkably reactive groups of molecules—that harden (or overcome) through chemical reactions, which are triggered possibly by combining it with other substances or heating it to the high temperature. Ordinary gelcoat formulated to be used with polyester resins and vinylester resins isn't going to adhere to epoxy surfaces, https://www.propanraya.com/id/produk/epoxy-fast-dry