A Nature study reports that electrically charged water droplets can damage protective coatings and corrode underlying metals, offering a new explanation for rain-induced wear beyond acidity.

Dielectric breakdown from charged drops enables micro-galvanic interactions and generation of oxidative species inside droplets, accelerating corrosion.

Researchers say the electrical state of a droplet, not just its chemistry or impact, can influence when corrosion starts.

The work was led by Hans-Jürgen Butt at the Max Planck Institute for Polymer Research, with collaboration from several universities and MIT.

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Experiments involved droplets rolling across everyday materials—leaf, PVC, and polystyrene—before hitting a Teflon coating.

Although charging events per droplet are small, the cumulative effect over years could matter for bridges, ships, monuments, and other exposed infrastructure.

Droplet charging depends on the surface, with measured differences up to tenfold, yet coating changes occurred under all tested conditions.

The phenomenon can occur with conventional materials and coatings in real-world settings, including bridges, hulls, and outdoor electronics housings, and may relate to natural atmospheric processes.

The effect appeared across multiple material combinations, suggesting it is not limited to a single coating or metal and may be relevant in natural settings like clouds and thunderstorms.

Control experiments showed boundary-area corrosion in structured substrates and even corrosion without direct impact, driven by slide-induced discharge at interfaces between insulating and conducting regions.

While modern thicker coatings may be less immediately affected, findings could explain long-term degradation of historic infrastructure and influence future protective materials research.