What causes water spots while drying a car?
Water spots form when droplets evaporate before they are removed and leave dissolved minerals or contamination behind. Hard water, hot paint, slow drying and missed areas around mirrors, badges and trim all increase the risk. Dry from the top down, start with horizontal panels that heat up first, and work quickly in warm weather. A deionized or filtered final rinse reduces mineral content.
References
- Hardness of Water, U.S. Geological Survey
- The Physical and Chemical Properties of Water, Drinking Water Inspectorate (UK)
- Hard water, Wikipedia
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