SB Seretreat 2423 is a 10% solids siloxane resin solution in a low odor solvent carrier that gives deep penetration into the masonry surface for a long lasting hydrophobic effect. In most cases, there is little or no color change in the appearance of the treated masonry. SB 2423 is a reactive copolymer which does not require a catalyst and will treat all porous masonry to form a durable water repellent surface and subsurface. Successful applications have been made on brick, concrete, unpolished marble, limestone, unpolished slate and sandstone. SB 2423 has the same performance of 2422 but is formulated with special solvents to meet the more stringent VOC requirements of the Ozone Transport Commission (OTC) member states. Do not thin or dilute as this will likely violate VOC requirements. Product not suitable for most split face hollow core block.