Sure Hard™ Densifier J17 is a colorless, odorless solution of specialized reactive chemicals that penetrate concrete surfaces to seal, densify and harden the material. Sure Hard Densifier J17 is a water based product and as a result is V.O.C. compliant in every area of the country and environmentally safe to use. Sure Hard Densifier J17 penetrates the concrete surface and undergoes a chemical reaction that turns the concrete substrate into a hardened, densified mass.