First “creative vandalism,” now “reverse graffiti”

I’ve written a couple of times about “creative vandalism,” but I recently stumbled upon something called “reverse graffiti,” which I’d put in the same broad category.
An English artist created a mural in a San Francisco tunnel using stencils and a spray cleaner that removed layers of dirt and soot covering concrete walls. The artist, named “Moose,” accomplished this in April 2008 in San Francisco’s Broadway tunnel. I’ve embedded a YouTube video of the project below and posted photos above.
You can read more about it at the Web site of the Reverse Graffiti Project. The project was sponsored by Clorox to promote its Green Works natural cleaners.