What Causes Black Streaks on White Cars After Rain?
2 Answers
The reason for black streaks appearing on white car surfaces after rain is: calcium oxide carried in rainwater deposits on the vehicle and forms these marks. They can be removed using water stain cleaners, cleaning wax, or clay bars. Methods for maintaining white cars include: 1. Regularly remove dust from the vehicle before, during, and after use to reduce static electricity's attraction of dust; 2. Rain spots on the car body will gradually shrink after rain, increasing the concentration of acidic substances in the rainwater, so rinse with clean water as soon as possible to avoid damaging the paint; 3. Use specialized car wash detergent and neutral water for cleaning, avoiding highly alkaline detergents or dish soap, to prevent stripping the paint of its protective oils and accelerating paint aging.
Those black streaks appearing on white cars after rain are mainly caused by rainwater washing away dust, pollutants, or residues from the air or the car's surface, such as industrial emission particles or bird droppings. The rainwater carries these substances along the car paint, leaving marks when dry. I often encounter this situation when washing my car, especially on white cars where it's more noticeable. The reason may be the high acidity of rainwater corroding the paint surface and attracting dirt, which is more evident in urban environments. It's recommended to wash the car promptly after rain or apply wax to protect the paint. This way, stains are less likely to stick, the car looks shinier when driving, and the paint's lifespan is extended, saving you from costly scratch repairs.
