Hard-water and calcium stains from sprinklers and hoses are shockingly hard to remove from auto-glass. Here’s what works.
Have you ever parked near an irrigation system that sprinkled your ride with water and left behind circles stained into the glass and outside mirrors? If so, you know that removing those stains is very difficult. Regular glass cleaner won’t help at all. We tried both Windex-style ammonia-based window cleaner, and also vinegar-based auto glass cleaner and found that neither has any effect on the stains. We went in search of a solution and tried about half-dozen suggested ways to get that stuff off. Only one treatment had any effect.
Hard-water is water that has a high mineral content. Typically the mineral of concern with regard to glass stains is calcium. Limestone underground is dissolved by the water that trickles past it on its way to the ground water supply. Municipal water treatment systems don’t remove this calcium because it is harmless to people. However, it can cause issues with any appliance in your home that uses a heating element and water such as your coffee maker, dishwasher, or electric tea kettle. The usual fix for calcium build-up is white vinegar. Soaking or running it through the machines removes the calcium. The acidic vinegar dissolves the basic calcium. We tried that first on our badly-stained BMW X3, and it made no difference. We could not get the vinegar to settle on the side windows and side mirrors long enough to have an effect.
The same was true of all the liquids we tried. CLR and similar gels and liquids we applied didn’t make the glass any clearer. Finally, we tried Bar Keepers Friend. This is a powder that contains gentle abrasives as well as chemicals. We followed the directions – and we want to emphasize this – tried it on a small area of the mirror and window first. There was no damage, so we continued. We simply used a damp paper towel to make a light paste from the Bar Keepers Friend. Using a gentle rubbing motion, we polished the surfaces, and the results were quick and remarkable. The glass was clear in under five minutes.
We wish to emphasize that BestRide did not receive any compensation from Bar Keepers Friend for this publication. The attached video is not ours. We offer it as a second opinion showing the great results. We like the advice to wash the car after doing this type of cleaning. Finally, one more reminder to try this on a small area of your own car first. Let us know if it works for you in the comments below.