Charged Raindrops Punch Through Protective Coatings, Accelerating Corrosion

A new Max Planck Institute study shows that raindrops can carry up to 9,000 volts, enough to electrically punch holes in paint, polymer films, and oxide layers on vehicles. The phenomenon, known as slide electrification, occurs when a drop slides across an insulating surface, stripping charge and leaving an opposing charge behind. The resulting electrical discharge can breach protective coatings without mechanical abrasion, exposing metal to water, salts, and oxygen that drive corrosion. The research suggests that conventional paint and polymer films may be vulnerable to high‑voltage impacts, leading to faster degradation of vehicle surfaces and increased maintenance needs.