Charged water droplets can damage protective coatings
The hidden effect could be another factor in weathering and lead to tougher coatings for cars, bridges and buildings.
Researchers at the Max Planck Institute for Polymer Research, Germany, and collaborating institutions, have discovered that water/rain droplets can pick up electrical charge while moving across a surface.
They dropped water repeatedly onto a Teflon-coated surface. After 3,000 impacts from uncharged droplets, no visible changes were seen under the microscope.
They then allowed droplets to roll over materials including PVC, polystyrene and plant leaves before hitting the coating. As the water moved across these surfaces, it picked up electrical charge. When the charged droplets struck the coating, they discharged locally, creating small points of damage in the coating and the metal beneath it.
The amount of charge varied by up to a factor of ten depending on the surface the water had crossed, but damage was detected in every test.
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