Phys. Rev. Fluids (in the press)

Spray some sea water and it will leave a salty deposit that might corrode the surface it has landed on. The salty crystals left behind as a result of evaporation can be damaging to ships, and strategies for their removal are needed. Samantha McBride and co-workers have captured a curious behaviour of evaporating salty drops that could be exploited for antifouling applications in a video shown in the Gallery of Fluid Motion (

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Samantha McBride and Kripa K. Varanasi (MIT)

The team placed a saline droplet on a hot superhydrophobic surface. As it evaporated, the droplet left behind a salty round casing, which in turn started growing salty ‘legs’ that lifted it off the surface. This peculiar — almost life-like — structure was created because once the salt globe formed, the evaporation continued at a few points where the globe was in contact with the very hot surface. Once evaporation was complete, the salt crystals had minimal contact with the surface and could be easily removed.