Miracle Sealants Grout Cleaner & Brightener is a heavy duty acidic cleaner designed to deep clean and restore heavily stained and discolored grout and tile. This professional strength grout cleaner quickly dissolves heavy build-up of dirt and grime, soap scum, hard water and mineral deposits, rust, efflorescence and other accumulated soils. Cleans and restores grout with minimal scrubbing. For use on porcelain, ceramic, slate and other acid-resistant stone and tile. Not recommended for use on polished marble or other acid sensitive natural stone. Grout Cleaner & Brightener is Ideal for use in residential or commercial bathrooms, kitchens, floors, walkways and other areas.