Epoxy resins are a class of pre-polymers and polymers containing more than one epoxide group. Through a chemical reaction called curing, epoxy resins are processed with other chemicals to produce epoxy polymers (more commonly known as epoxies). The vast majority of epoxy resins are industrially produced petroleum derivatives. Today, hundreds of resins and mixtures are available, the most common produced with epichlorohydrin and Bisphenol A.