TileLab grout haze remover is premixed, ready-to-use mild acidic solution. Removes dried Portland cement grout haze and mortar residue from tile, concrete, and masonry. Safe for use on colored grouts. Removes hard water deposits, efflorescence and also etches concrete. Grout haze remover is used for removal of dried Portland cement grout and mortar residue from the surface of glazed and unglazed ceramic tile, concrete, and masonry. It is ideal for neutralizing efflorescence. It can also be used to slightly etch concrete surfaces to create a better bond for adhesives. May etch some glazed tile. Do not use on marble or polished stone. Do not allow product to contact metal objects. Do not transfer contents to unlabeled containers. Coverage: 1 quart will clean approximately 75 sq. ft. area.