The same water you use to wash your car to keep it clean can also damage the paint. The spots and damage are caused by the minerals in the water. When water evaporates off of your car's paint, it leaves behind the trace elements it contains. Calcium and metals are the most damaging ingredients found in your tap water. Rainwater may contain damaging acids from air pollutants.
Getting rid of water spots is easy if you chase after them. The best solution is to use a quick detailing spray after you wash, or as soon as you discover the spots (i.e., when your neighbor's sprinkler gets you).
If the spots are allowed to dry and bake on, they will attach to and harden on your paint. When this happens, you need to use a mild acid to get them loose. Believe it or not, the best acid is also the least expensive and most available: a gallon jug of distilled white vinegar.
Expert car detailers have known this secret for years. If you take your car to a pro, they will tell you about the "magic acid bath" and charge you $60 or more for the pleasure of smelling like a pickle. Save the $60. Put on some gloves and get to it.
To give your car the magic acid bath, first wash your car with your normal car shampoo, rinse, and then use the distilled vinegar. Just wipe it on with a sponge, and rub it in. Do one section at a time. Let it sit 30 to 60 seconds, and then rinse. When you're done, wash the car again with shampoo, and then rinse. By the way, vinegar will remove your wax, so be prepared to re-wax your car after the vinegar treatment.
Removing Cement Splatter
Not long ago I received a letter from a young couple in Pontiac, Michigan thanking me for saving them nearly $3,000. I had received a frantic call from the woman explaining how she parked her husband's car near a construction site and it was splattered along the front and down one side with cement. Making matters worse, the cement stain was not noticed until two days later, and her husband was out of town.
On the recommendation of their insurance company she took the car for an estimate at a paint and body shop. Their estimate was $2,700 to remove the cement and repaint the car and another $240 for a rental car. This is not an uncommon story.
As a friend of mine used to say, "When all you have is a hammer, everything looks like a nail." Unfortunately, insurance companies and paint and body shops don't know how easy it is to solve this problem. The answer, as with hard water spots, is distilled white vinegar.
I learned this little trick from the old man that taught me how to plaster walls. Every day I watched him wash his hands from a gallon jug of vinegar. I thought he was strange until my hands became so chapped and dry they started cracking. The vinegar was instant relief. It's instant relief for your car, too.
The solution is really easy. Pour vinegar into a small bucket and use it to soak a clean sponge. A grout sponge from the hardware store works the best.
Place the sponge on the cement splatter stain. WARNING... Do Not Wipe! All you want to do is soak the cement stain with vinegar. Let the sponge sit on the stain for 2-3 minutes so the vinegar can do its job. Then flush the area with clean water. Repeat as necessary.
Paint Etching Caused by Water Spots or Cement Splatter
If water spots or cement stains are allowed to stay on your car's paint for more than a few days, the minerals will etch the paint. In this case, using vinegar will remove the stains, but the paint will have etch spot (dimples) damage. The only way to fix this problem is to polish the paint using a dual-action car polisher, like the Porter Cable 7424XP.
You can polish all day by hand and you won't make the etch marks go away. To do the job correctly you will need a dual-action car polisher, a foam cutting pad, a foam polishing pad, and Meguiar's Ultimate Compound. You might think that you can cheap-out on this and do the work by hand. Trust me, you can't. You'll rub, and rub, and rub and won't make a dent in the etch marks. Modern clear coat paint is too hard.
Your alternatives are to invest in a good car polisher kit, like this Griot's Garage Polisher Kit or this Porter Cable Polisher Kit, or hire a professional detailer to do the job for around $250 to $400. You'll save money doing it yourself.
See our Dual-Action Car Polisher Guide to learn more about safe car polishing.
Next in our Paint Repair Clinic Series: How-To Safely Remove Road Tar, Tree Sap & Bugs.