Max Planck researchers find charged raindrops corrode surfaces

Researchers at the Max Planck Institute for Polymer Research have discovered that raindrops can carry significant electrical charges that cause damage to surfaces, including cars and buildings. This phenomenon, known as “slide electrification,” occurs when water droplets move across surfaces like leaves, window glass, or plastic, stripping charge from the material in a process similar to tribocharging.

In experiments led by Zhongyuan Ni, Rüdiger Berger, and Hans-Jürgen Butt, researchers observed that these droplets can reach voltages as high as 9,000 volts. When these charged drops land on surfaces, they do not merely scratch or dissolve protective coatings; instead, they can effectively “blow a hole” through insulating layers.

During testing, the team dropped salt-containing water onto copper plates coated with Teflon, one of the most chemically resistant materials available. After thousands of drops, the electrical charge was found to degrade the Teflon and corrode the underlying copper. This finding suggests that current methods for preventing corrosion, which primarily focus on chemical resistance and physical abrasion, may need to account for electrical discharge.