Auto Detailing FAQs | Removing Hard Water Spots from Glass

June 29, 2010

Hello, oh ye faithful “Adventures in Detailing!” followers!   We have been asked, yet again, “How do you remove hard water spots from my windshield?” Since this is such a commonly asked question, I think it is time to revisit it (last time was in February, I believe). So here goes:

DO NOT use either method on the glass of your rear-view (side) mirrors, it is way to fragile for either of these methods. Consult a professional.

Polishing method: (This is the method i recommend for the front windshield)

  • items you will need:
    • glass polish
    • clean (not necessarily new) terry cloth, or #0000 steel wool, or Scotch-BriteTM pad
    • chamois
    • glass cleaner, terry cloth, microfiber
    • shaded area. Make sure the glass is cool to the touch during this operation.
  • With Terry Cloth:
    1. Fold your terry cloth so that you can easily manage it with one hand. glass polish1
    2. Hold most of it balled up within your fist so that you do not accidentally get your glass polish on your car’s paint. A glass polish is for glass only. Use your knuckles on the folded part of the terry cloth to give yourself a little extra pressure if needed without straining your fingers. (Read the instructions on your glass polish, some of them, like Diamond MagicTM are abrasive enough to scratch glass if you use too much pressure.
    3. Work the polish into the glass with fairly small circular motions (except along the edges and corners). If you do not use too much polish glass polish2you should be able to see the hard water spots through the polish & feel a gritty texture when you first start. As you continue to work on it, you should feel the area smooth out & see the hard water spots in that area disappear. Continue until that half of the windshield is done. You will probably need to work harder around the rim of the windshield, where the wipers do not touch, however, do not neglect the face of the glass as well. I can’t tell you how many times I’ve had guys produce great results around the rim of the windshield, but end up with cloudy (water spotted) areas within the wiper blade area because they didn’t think it needed to be done. If you get the glass really clean, you will notice the difference.
    4. Dampen your chamois, wipe off the glass polish residue, then proceed to the other side.
    5. repeat steps 1 – 3 above on the other half of the windshield.
    6. use your glass cleaner to remove any remaining residue & make your glass sparkling clean!
  • with #0000 steel wool or Scotch-BriteTM pad
    1. dampen your steel wool before proceeding. Lubricating your steel wool is always a good precaution to help prevent scratching.
    2. use the same steps as with the terry above. You should not need to use as much pressure & should be done fairly quickly in most instances. If you still have hard water spots (irregular ovals, made by the minerals concentrating along the edges of the water spot as they dry) after using steel wool & glass polish I would recommend seeing a professional. Chances are your glass has been etched by an acid content within the water spot (often found on the Big Island and Mainland) or by the sun magnifying it’s rays with the water spot (this usually takes a while to actually do damage, but sometimes we have to high speed polish after a car has been hit every day for more than 3 months with water sprinklers).

Liquid water spot removal method:

Make sure your glass is COOL (not even warm, COOL) to the touch. If your glass is etched by grit from the wiper blades, it will quite likely stand out after you are done & quite possibly be a distraction while driving. You may want to have a professional look at it, instead. (Then again, if you’re considering replacing the glass anyway, this method might be worth trying first.)

  • you will sometimes hear people saying to use white vinegar. That is because vinegar is acidic & can melt out the hardened minerals in the hard water spot. Combine #0000 steel wool & a chemical wash or liquid water spot remover (yes, feel free to use white vinegar if you like, anywhere from one part vinegar & two parts water, to straight vinegar for a stronger solution) as a lubricant (again, this is only for glass, not paint).
    • If you have drips running down from your window over the paint of your car, they can stain your paint.
    • if you rub glass polish over your paint, it CAN & probably WILL scratch your paint
    • if your rub steel wool on your paint, it WILL leave scratches on your paint
    • wear gloves.
    • if you are misting the windshield with a chemical, wear a respirator…or at least a bandanna to keep excess chemical fumes/mist out of your system.

Well, those are your two most prevalent home-gamer methods. Both are not without their own inherent dangers, but can be very effective, & can yield outstanding results if done correctly.

As always, please feel free to call me if you have any questions.



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