Reverse graffiti  Reverse graffiti, also known as clean tagging, dust tagging, grime writing, clean graffiti, green graffiti or clean advertising, 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 removing dirt/dust 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 artist Paul Curtis (aka Moose) is one of the first street artists to make an art piece using the reverse graffiti technique. He discovered the technique at his dishwashing job, and in 2004 used detergent and a wire brush to create designs in the dirt on pavements and walls in Leeds and Manchester. 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. As with traditional graffiti, the technique is also used commercially as a form of out-of-home advertising. In this context, marketers call it "clean advertising" or "clean graffiti". Reverse graffiti has been described by promoters as an environmentally friendly form of advertising, since it is temporary, and can sometimes be done with innocuous or biodegradable materials. Companies such as Microsoft, Channel 4 and Smirnoff have advertised their products in this way. In response to Moose's use of the technique for advertising in Leeds, a city council representative described the work as "illegal advertising". Leeds council later attempted a 12-month trial program allowing clean advertising in exchange for a percentage of fees. The program was criticised by local officials. In 2011, a Swindon, UK advertising firm was fined by the city's council for a reverse graffiti campaign. In the Netherlands one needs to have a permit for commercial advertisements in a public space even if nothing is being destroyed. In Hungary under the name "inverz graffiti" companies and brands like The Coca-Cola Company with "It's Rite" for Sprite, Monster, Deutsche Telekom's local arm Magyar Telekom, Manpower, Ringier publishing house for launching its Népsport blogging platform, TUC advertised with this tool.