Key facts
- Raindrops can carry electrical charges up to 9,000 volts.
- Water drops sliding across surfaces accumulate charge through slide electrification.
- Charged drops can breach insulating coatings like Teflon and polystyrene via dielectric breakdown.
- This electrical discharge leads to corrosion of underlying materials like copper.
- Damage accelerates over time and can create new chemical bonds in polymers.
A new study has revealed that raindrops can carry significant electrical charges, capable of damaging protective coatings on surfaces and causing corrosion. Researchers at the Max Planck Institute for Polymer Research found that water drops, after sliding across insulating surfaces like leaves or painted walls, can accumulate charges up to 9,000 volts. When these charged drops land on a surface, the electrical field can exceed the breakdown threshold of coatings such as Teflon or polystyrene, causing a miniature dielectric breakdown. This process effectively punches a hole through the coating, exposing the underlying material to corrosion. The study demonstrated this by repeatedly dropping charged water onto a Teflon-coated copper plate, which resulted in pits and corrosion despite the protective layer. The damage was observed to worsen over time and accelerate as breached spots held more water. This phenomenon offers a new understanding of how rain can degrade materials, beyond the traditional explanations of dissolved salts and abrasion.