Stain and Spot Removal
You will run into some spots or stains that cannot be removed with a scrubber or razor. You have a few options to handle these tougher spots.
You can use either extra fine Steel Wool (grade #0000) or a Stain Remover. Stain removers can go from very mild to extremely acidic solutions! If you want to know more about hard water stains, check out this guide for a more in-depth explanation.
*Make sure you wear rubber gloves and eye protection when using any stain remover
*Steel Wool and Stain Removers will scratch film and coated windows. They may also scratch tempered glass
The only disadvantage to using steel wool is that it shreds as you use it. The little shreds will rust if not cleaned up after use.
Mineral deposit remover will remove most of the stains from glass created by runoff from bricks or cement, sprinklers, and metal screens. You will need to wear gloves when using mineral deposit removers. Some of them contain acid. Most contain solvents and fine grit that dissolve and polish away the deposit
WHAT IS HARD WATER?
Hard water is water that has high mineral content. It is formed when water filters through deposits of limestone and chalk. When hard water comes in contact with glass, it leaves behind ugly "water spots" or "tear drop" shaped deposits.
HOW TO REMOVE SPOTS & STAINS?
The easiest way to use the mineral deposit remover is to first apply your solution to the glass. Then put some mineral deposit remover on a damp towel or scrubby pad and apply it to the glass. Work it all over the glass.
As the deposits are removed, it will become easier to work the towel over the glass. You will feel a slight resistance as you are rubbing the spots where the deposits have not yet been completely removed. Keep the glass wet as you do this.
While the material is still wet, quick-wipe and squeegee the glass. Do not use your scrubber to add solution to the glass if the mineral deposit remover has dried out too much to squeegee. You do not want to contaminate the scrubber with a lot of mineral deposit remover. Wet a towel and rub it around on the glass to get it to a point that you can squeegee it. After squeegeeing, wipe any excess mineral deposit remover from the glass and frame. At this point, you can wet the window and squeegee the glass in a regular manner. It may need to be done twice to remove all of the mineral deposit remover.
It is possible you will not remove all of the spots the first time. If many deposits still remain, just repeat the procedure.
If you only have a few spots that did not get removed, rub the spots with the mineral deposit remover and wipe the spots with a clean towel. Wet and squeegee the window again.
If you are dealing with mild hard water stains and want something gentle but effective, a paste or cream will do. If you are working with really bad hard water stains you may need a more aggressive stain remover, something acid based.