Reverse graffiti

Reverse graffiti is a method of creating temporary or semi-permanent images on walls or other surfaces by removing dirt from a surface. It can also be done by simply removing dirt with the fingertip from windows or other dirty surfaces, such as writing "wash me" on a dirty vehicle. Others, such as graffiti artist Moose, use a cloth or a high-power washer to remove dirt on a larger scale.

Reverse graffiti has been used as a form of advertising, although this usage has been controversial, as its legality varies depending on jurisdiction.

English graffiti artist Paul "Moose" Curtis is one of the first street artists to make an art piece using the reverse graffiti technique. Curtis discovered the technique while working as a dishwasher in a restaurant; when he attempted to wipe a sauce stain from a wall that he assumed to be brown, he found that it was a white wall stained by cigarette smoke, and that his cleaning rag had left a trail like white spray paint. From there, Curtis began his career in the music industry eventually going on to manage a record label. The technique gained traction once Moose began promoting an album for his record label in Leeds, England.

Curtis had some legal trouble with the British Council, who were undecided on the legality of reverse graffiti. Curtis has said: “I felt like I created this really curious process that flipped the laws and made it really awkward for the legal system to deal with... it was just in a beautiful gray area..."

The first large-scale reverse graffiti art piece was made by Alexandre Orion in 2006. The intervention was called Ossario (ossuary) and was over 1000 feet long. The municipality of São Paulo washed it away on July 26.

Reverse graffiti is a subtractive process, most often 'cleaning' dirt and pollution from public areas to leave behind messages and/or art pieces. The process has also been linked to the term 'reverse-pollution' literally describes the process of undoing or cleaning pollution caused by human interaction.

It is estimated that one 55-inch square requires 4-5 gallons of water to create an impression; this is around thirty times less than is needed to produce a paper poster of comparable size.

There are a few different ways to approach reverse graffiti.