Epoxy resin systems are chemical mixtures containing two main parts: epoxy resin and curing agent. When combined, these chemicals form a hard and durable plastic material commonly known as epoxy. Epoxy resin systems also contain other chemicals such as thinners, pigments and fillers. The greatest common epoxy resins are glycidyl ethers of alcohols. Liquid epoxy resin is the diglyceryl ether of bisphenol-A (DGEBA) and accounts for more than 75% of the epoxy resin used in industrial applications. The most common curing agents come from a large class of compounds called amines. Both of these components are potent skin irritants.
Epoxy molecules are very reactive and easily combine with curing agents. This process, known as cross-linking and curing, produces very strong bonds. As the mixture cures, it hardens. Depending on the desired characteristics of the final product, epoxies may cure in a few minutes, may require more time and heat.
Chemical additives such as plasticizers, solvents, fillers and pigments are mixed with the epoxy resin system to speed up the process and to produce a certain effect. Fillers include fiberglass, calcium carbonate, powdered metals, pigments and sand. Solvents may be present in the epoxy resin system and may be used to clean up equipment and spills in areas where epoxies are handled. Commonly used solvents include acetone, methyl ethyl ketone, toluene, xylene, glycol ethers and alcohols.