Blok-Lok Concentrate (Makes 40 Gallons) Silane Siloxane Professional Grade Water Repellent Sealer - Concrete, CMU, Block, Brick, Stucco, Stone for Vertical Surfaces, 5 Yr Warranty For Use On Concrete, Brick & Wood When applied, Blok-Lok forms a long-chain water repellent barrier deep within the masonry surface This hydrophobic barrier repels water yet remains highly vapor permeable and allows moisture to esca Coverage depends on the substrate being applied on porous or non-porous surfaces Coverage ranges from 60 - 150 sq/Gallon