Raindrops can damage paint with microscopic “lightning”
Researchers have discovered that water droplets can carry an electrical charge that acts like microscopic lightning when striking surfaces. This phenomenon contributes to the degradation of protective coatings on structures like bridges and buildings.
Why it matters
Understanding this mechanism could lead to the development of more durable protective coatings, saving significant costs in infrastructure maintenance.
Paint exposed to the elements does not last forever. A garden fence may need a fresh coat after only a few years because weather has gradually worn the surface down. The same basic problem affects far larger structures, including the Eiffel Tower and the Golden Gate Bridge, which require extensive repainting to keep their protective coatings in good condition.
Scientists have traditionally attributed this type of deterioration to two major processes. One is mechanical stress, in which repeated contact with water droplets creates friction that slowly erodes a coating or causes pieces of it to peel away. The other is chemical damage, especially when the water contains substances such as acids or salts.
Now, researchers have identified an additional mechanism that had largely escaped attention: the electrical charge carried by water droplets.
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