Max Planck Study Finds 9,000-Volt Raindrops Punch Holes in Coatings
Updated
Updated · Ars Technica · Aug 31
Max Planck Study Finds 9,000-Volt Raindrops Punch Holes in Coatings
3 articles · Updated · Ars Technica · Aug 31
Summary
Charged water drops in lab tests pierced a 60-nanometer Teflon coating on copper, pointing to a corrosion mechanism beyond salt, acid and mechanical wear.
The Max Planck-led team says raindrops gain charge through slide electrification as they move across insulating surfaces, with measured voltages reaching about 9,000 volts.
In the experiments, 35-microliter saltwater drops slid 4 centimeters down surfaces tilted at 50 degrees, then fell 5 millimeters onto the coated metal target.
Drops picked up 0.2 to 2 nanocoulombs from a plant leaf, PVC foam board, polystyrene glazing and fluorinated quartz, suggesting everyday surfaces can prime rain to damage protective films.