Epoxy coatings are composed of two distinct parts mixed before application. The two parts contain an epoxy resin, combined with a hardener or co-reactant. The formulation of epoxy coatings is done depending on the final product. With proper formulation and application, epoxy coatings produce a hard finish that is also resistant to solvents and chemicals. These coatings are commonly used on steel and concrete to make the surface resistant to water, acids and alkalis. The combination of the epoxy components used in the formulation, determines the suitability of the coating to a certain environment.