I’ve come across several sites that celebrate “reverse graffiti,” public displays created by people (artists?) who find dirty walls and clean them, but they don’t clean them completely. They leave some of the dirt so that there are designs or messages.
Reverse graffiti also known as clean tagging, dust tagging or grime writing, is a method of removing dirt from a surface while creating graffiti on walls or other surfaces. It is usually done by removing dirt/dust with the fingertip(s) from windows or other dirty surfaces. Reverse graffiti on windows/glass can be highly visible due to the reflection of sunlight.
Links to the Web sites of a couple of the artists, Paul Curtis’ (“Moose”) Symbollix and Alexandre Orion’s Ossario; NPR’s Artist Draws ‘Clean’ Graffiti from Dirty Walls (with photo gallery), the Wikipedia entry on reverse graffiti (source for the quote here), soap-not-spray-can-reverse-graffiti-art, Automotive Ossuary (29 November 2006), REVERSE GRAFFITI: Clean Green Street Art. Because people began covering this story several years ago, I hesitate to categorize it as “news” …sigh.