Ultra-Block™ is an economical water based specialty sealer formulated for six sided, dip-sealing, underside & pre-grouting sealing. Helps resist staining caused by water soluble minerals (including picture framing effect) which are normally absorbed through the back of the stone during installation. It also helps resist ef orescence migration & adhesive blotch marks. Can also be used as a pre-grouting sealer. Allows moisture vapour transmission (MVT).