CRL M64 smooth polyurethane construction sealant is a specially formulated high performance polyurethane sealer that results in a sleek and professional looking appearance. When cured, it has a smooth and even consistency and surface. Designed to be used indoors or outdoors, this high grade polyurethane sealer emits low odor and cures 72 hours after application. CRL M64 smooth polyurethane sealer seals moving joints like expansion, precast concrete panel joints, curtainwall joints and all types of perimeter caulking of masonry, windows, doors, skylights and many other panels and frames. CRL M64 smooth polyurethane sealant requires no priming when applied to brick, concrete, aluminum, wood, or granite. It applies with any standard cartridge size caulking gun to clean and dry surfaces.