A Chemical Assist

• Stone cleaners will remove hard water stains and the mineral buildup that causes them. You will want to look for an alkaline---low- to no-acid---heavy duty cleanser for natural stone or granite. These products can be applied with a brush, sponge or a cloth and basically chemically chelate, or release, the deposit's bonds off of the surface so that you can wipe them away as residue. Example brands of this type of product include DuPont Heavy Duty Stone & Tile Cleaner, MB-3 Natural Stone Cleaner and TileGuard Marble & Granite Cleaner. All of these are applied, allowed to activate and set for a period of time, and then are scrubbed or wiped clean and rinsed off. It is important to follow the instructions for each specific product when applying, for optimal results.
  
  

Fine Abrasion & Scraping

• If you do not want to use a chemical, or simply don't want to have to make a trip to the hardware store, you can often remove the hard water buildup by gently abrading or scraping the deposits from the granite surface. Hard water stains can be buffed from granite with a wad of super-fine 0000 grade steel wool without damage to the granite surface itself. Wear gloves when working with steel wool, use a mild dish soap or water as a solvent and buff in a gentle circular motion, moving over the stained area until the deposits lift.
  
  An alternative is to dry scrape away the deposits with a fresh razor blade. Hold the blade almost parallel with the granite surface, and use a sliding and gently chipping motion to scrape the hard water deposits away. Work in one direction, and keep the blade as close to parallel as possible at all times. Wipe away the residue as you work to have a clear field of vision over what buildup remains to be removed. If you have a very thick buildup of deposits and still want to use a stone cleaner, you can just knock down the most protruding bits of the buildup with a blade and then apply the cleaner to what is remaining to speed up the removal process considerably.