What Are Hard Water Stains Made Of?

• You should wash your windows twice a year to keep windows from staining. Caustic chemicals allowed to sit on glass will eventually etch exposed glass and no amount of scrubbing will make it look clean. Hose down of your exterior house windows to rinse off the hard minerals. Rain water contains dirt, acids, diesel and gas fumes, salt, calcium, magnesium, chromium and other pollutants. Water droplets form around particles which float in the air. The pollutants can eventually eat into the glass or leave ringlets of dried chemicals on the glass.
  
  

Getting Rid of Hard Water Stains

• Vinegar and water can remove water marks from crystal or drinking glasses if they soak for about a half hour. But you can't soak your windows so you'll have to use other cleaners. Buy commercial spray glass cleaner that has ammonia works better and faster than vinegar and water.
  
  Abrasives, such as toothpaste or a soft-scrubbing cleaner, will eventually scratch glass. The best way to get rid of hard water stains is by scrubbing with a rag soaked in glass cleaner spray or a weak ammonia and water solution, then drying vigorously twice with a clean towels.
  
  

Getting Tough

• If the stain persists, scrub with a very fine bristle brush, like an old toothbrush, and toothpaste. If that doesn't work, gently scrub with detergent and a very fine steel wool pad. If that doesn't, hold a razor blade flat against the glass and move it back and forth against the glass to remove any trace elements which stick up from the surface. If a razor does not work then the chemical has etched below the surface and more scrubbing will scratch the glass.