On April 15, 2008, Paul 'Moose' Curtis, an English reverse graffiti artist entered San Francisco's Broadway tunnel to create an environmentally friendly work of art over the course of one very late night. This project was filmed by documentary filmmaker, Doug Pray (Surfwise, Big Rig, Infamy). Curtis' technique uses natural methods and natural cleaners (in this case Green Works plant-based, earth friendly cleaners) to create a large scale "clean" mural.