SL-15 is a penetrating, below surface sealer to resist water based staining on unglazed ceramic tile, brick, concrete, stucco clay and other masonry surfaces. It is non-flammable and does not change the natural appearance of the applied surface. SL-15 is used to protect unglazed ceramic tile, brick, concrete, stucco clay and other masonry surfaces against water penetration and stains. SL-15 may be used as a grout release by pre-sealing over the clean tile surface 16 to 20 hours before grouting the floor. ALWAYS TEST A SMALL AREA BEFORE GENERAL APPLICATION.