Epoxy resins are thermosetting products known for excellent surface and sub-surface adhesion, mechanical properties, and chemical resistance. Epoxy resin systems are made up of an epoxy resin and a curing agent (also called a hardener or catalyst). Many epoxy products also contain additives such as organic solvents, fillers such as fiberglass or sand, and pigments.
When epoxy resin systems are used, single molecules (monomers) of the epoxy resin chemical and the curing agent combine to form long chains of molecules (polymers). As the mixture “cures,” it becomes a hard polymer. Some epoxies cure in a few minutes at room temperature. Other epoxy systems need additional time or heat to harden. The characteristics of hardened epoxies (such as whether they are firm or flexible, or resistant to heat or chemicals) depend on which epoxy monomers, curing agents, solvents, and fillers are added.