Sliding raindrops build up to 9,000 volts.

Corrosion models for aircraft and bridge coatings omit this electrical mechanism entirely.

The charge punches through a coating’s insulation before the drop even touches the metal, researchers found.

Thicker coatings resisted the damage, but aircraft and optical coatings must stay thin.

How each outlet framed it
Ars Technica
identifies slide electrification (9,000-volt charge) as overlooked electrochemical mechanism puncturing protective coatings

Sources: Ars Technica