Casting Materials

Step 1: Understand the chemistry of polyester/fiberglass casting. Fiberglass casting uses a thermosetting plastic, typically polyester resin, which must cure from a liquid to a solid. This curing is a chemical reaction. The glass fiber mat is the reinforcement, not part of the chemical setting mixture. A gel coat is an optional surface layer.
Step 2: Identify the roles of the chemicals. The Resin is the main polymer body. The Catalyst (like MEKP) is the initiator that starts the polymerization reaction. The Accelerator (like cobalt) is a chemical that speeds up the reaction started by the catalyst, allowing it to cure at room temperature. These three components form the chemical mixture for setting the resin.