Despite any downsides associated with rain, when liquid water condensed from atmospheric water vapor forms into droplets and falls back to Earth's surface, there's a shift in mood. Days aren't normal when it rains, they're rainy days: Days when we sit inside with a cup of hot cocoa and a fat wedge of Game of Thrones dragon cake. Days when binging our latest favorite series isn't all that guilt-inducing, because... well, what are we supposed to do, get mildly wet?! Days when invisible street art appears as if by magic, and delivers to passersby tiny messages of hope. And also maybe hopscotch.
That last miracle of the rain is possible thanks to something called superhydrophobic coating, which Peregrine Church and his company, Rainworks, have utilized as a way to create cement art that only comes out when exposed to water. Although Church isn't the original inventor of the coating, he helped to popularize this particular usage for it by using it as a spray in conjunction with stencils.
The above clip, a GIF of which was first posted to reddit by user SuperXack, shows off the myriad hidden visual treats that can be created with superhydrophobic spray. It works particularly well on cement because cement, of course, changes color when it becomes wet.
Superhydrophobic spray is capable of shedding water the way it does because it develops a nanoscopic surface layer that behaves much like Teflon. The superhydrophobic spray that makes up the slick sidewalk art doesn't actively repel water, but as a hydrophobe, it is not attracted to water. Some of the more practical uses, street art aside, include coating for solar panels (so they don't become wet and moldy), as well as a cover on rain coats: those things you should slip on the next time it rains so you can go outside and let out your inner Michelangelo or Banksy.
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