Impregnating Sealer protects and seals Highly Porous un-glazed tiles, quarry tiles, slate & natural stone from penetrating liquid ingress and dirt absorption. It is designed to penetrate into porous and semi-porous tiled surfaces and grout joints to form a water repellent seal which still allows any damp remaining in the substrate to evaporate, but restricts any further moisture ingress and dirt accumulation which can damage the structure and tarnish the surface finish. It is suitable for interior and exterior use.