Zinsser WaterTite Clear Mold & Mildew Proof Floor & Wall Paint is a modified acrylic copolymer designed to form an impermeable, smooth, non-pigmented barrier to water on a bare masonry wall and floor surfaces. It is used on interior or exterior, vertical or horizontal, concrete block (not lightweight block), and cast-in-place concrete. It stops moisture from entering or exiting a concrete surface. WaterTite Clear Mold & Mildew Proof Floor & Wall Paint meets ASTM D-7088 Resistance to Hydrostatic Pressure and ASTM D-6904 Resistance to Wind-Driven Rain.