Demystifying Iron Decontamination and Water Spot Removal
The two most annoying paint surface defects are iron particles and water stains. While they may look like harmless mineral deposits, both can do serious damage to your car's paint. Brake dust, rail dust and other Iron deposits can create rust under the paint, especially if there are paint chips. Water particles from reclaimed water may actually etch and corrode over a period of time. Washing the car will get rid of dirt on the top layer, but won't do much for particles that have bonded to the clear coat.
The best way to remove iron is to use a fallout remover or wheel cleaner. Many of these products turn purple, letting you know they are working. The surface should be cool and dry before spraying on the product. Let it sit for two to seven minutes and rinse thoroughly with spot free water. Be sure to wear disposable gloves and eye protection. Many people opt for a respirator mask as well, because most of these products have a distinctively foul-smelling odor.
For removing water spots, mild acid may do the trick. If that doesn't work, the next steps would be to clay and then polish. Some people use distilled water and white vinegar, but results have been inconsistent.
Detailing spray, a clay bar and a microfiber towel may remove a some of these contaminants, but are not particularly effective on their own. The down side is that your work time will double or triple. Even more important, it may make the problem worse by creating micro scratches. It's best to save this step for after. To prevent future buildup, apply a coat of wax or paint sealant every six to twelve weeks.