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How to Remove Acid Rain Spots From the Exterior Paint of a Black Car

by Sierra Rose

From the Batmobile to the Bandit car, no auto color looks sleeker, smoother or shinier than black. Unfortunately, coolness comes at a price. Black paint is especially prone to acid rain spots, according to the Environmental Protection Agency. Prevention by frequent washing and indoor storage is the best solution. But if acid rain spots are already marring your black exterior paint, detailing clay may reduce their severity. While most soaps and polishes remove debris from the surface of the clear coat, clay penetrates the top layers to remove tough spots.

Step 1

Wash your car to remove any surface debris. Measure out the correct amount of car soap into a bucket, and add water. Apply the soapy water with a soft sponge or brush to areas of a few square feet at a time, rinse and dry with microfiber cloths. Continue until the entire car is washed and dried.

Step 2

Knead a bar of detailing clay almost like a ball of dough, using pressure from both thumbs to warm and soften the bar until it becomes flexible enough to roll along the surface of your vehicle. Flatten clay into a disc-like shape.

Step 3

Spray the lubricant that came with the clay bar kit liberally over approximately one square foot of your car. Consider parking your car in the shade if it is very sunny outside to reduce lubricant evaporation. Clay is mildly abrasive, and the lubricant is meant to protect the paint surface from scratches and scuffing.

Step 4

Rub the clay across the lubricated area, using your fingertips to apply medium pressure. Try to push down hard enough to keep the clay in constant contact with the surface, but without scraping. Keep moving the clay back and forth until the surface feels completely smooth. If the paint begins to dry out, apply more lubricant.

Step 5

Work in small areas until the car is complete. As you go, pick out any large pieces of debris from the bar, or roll the dirty clay surface inward and re-flatten so you have a fresh surface.

Wash and dry your car again. Apply a protective wax or sealant to the black paint.


  • Consider cutting the clay bar into two or more pieces with a utility knife. That way, if one piece falls on the ground and becomes too dirty to use, you'll still have a fresh bar.


  • The longer acid rain spots are left on exterior paint, the more likely they are to stain permanently. Wash your car every time it rains to prevent spots from etching too deeply into the paint surface.

Items you will need

  • Bucket
  • Hose
  • Car soap
  • Sponge or brush
  • Microfiber towels
  • Detailing clay kit
  • Wax

About the Author

Sierra Rose is a California-based freelance writer whose work has appeared in several newspapers, the "Sierra Style" family of magazines and on numerous business websites. She previously worked as a business and finance reporter and has since branched out to cover news, home and garden topics. Rose has a Bachelor of Arts in economics from Sacramento State University.

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Photo Credits

  • black car image by Viachaslau Makouski from