Sika Thoroseal Gray Masonry Waterproofer, 50 lb. is a heavy, cement-based waterproof coating that comes in a dry powder form, ready to be mixed with water and applied using a coarse fibered brush. Designed for use on concrete, stone, brick, or block surfaces, it is suitable for both interior and exterior applications, whether above or below grade. This product exceptional filling qualities that ensure complete sealing of masonry surfaces. Its breathable formula prevents the build-up of water vapor, which can cause blistering, flaking, and peeling of paint films and other non-breathing coatings. Thoro Thoroseal can be painted over with acrylic paint and is compatible with concrete and masonry, effectively becoming part of the wall itself. It is even safe for use in cisterns and meets Federal Specifications. For maximum waterproofing above grade, apply a base coat at 2 lb. per square yard followed by a second coat at 1 lb. per square yard. The product is packaged in 50 lb. polyethylene-lined bags for durability and ease of handling.