What is EP52 Epoxy Primer? Oncrete® EP52 is a two-component waterborne epoxy system specially designed to adhere and protect mineral substrates. Used on it own it will protect your concrete by dust proofing it and by providing excellent stain resistance to oils and other contaminants. It can also be used as a primer for subsequent topcoats such as waterborne and solvent polyurethanes and 100% solids epoxies. Packaging Size 12L Kit (8L Part A: 4L Part B)