This acidic solution breaks harsh deposits of calcium with its concentrated solution, and removes stains and buildup that other cleaners in the markets can not. ZEP Commercial Calcium, lime and Rust Stain Remover can be used to clean tubs, sinks, toilets and brick. All you need to do is pour it on the designated surface, or dilute it with water and apply with a scrub/sponge. The application works within 5-10 minutes, leaving the surface cleaner and safer. Hard water stains can also be removed using Zep rust remover. This versatile, multi-surface cleaner is a perfect fit for all your needs