Remember Green Street Media's no-spraypaint-necessary sidewalk advertising? To refresh your memory, the UK-based firm exploited the filthy nature of sidewalks by placing a stencil over them and blasting them with a pressure washer. With the stencil lifted, the area blasted clean spelled out their message.
Green Street Media
Seattle-based artist Peregrine Church does something similar, but using rain rather than a pressure washer. By coating the sidewalks in an invisible superhydrophobic coating applied through a stencil, he creates messages that are only visible when it rains out.
Peregrine Church Peregrine Church Peregrine Church
Here's how he does it, and it seems simple as pie:
So at this point we've seen hydrophobic coatings used to defeat public urinators and help get glue out of bottles. Church's "Rainworks" project, as he's calling it, has a more humble purpose: "To make people smile on rainy days."
You can see more of them here.