Reverse graffiti is the act of tagging a message by cleaning it onto a surface. It’s done using a power washer, cleaning chemical and sometimes acid. As far as Vancouver is concerned it’s still graffiti and therefore still illegal. Young marketing firms use graffiti as an effective method of guerrilla marketing. GreenGraffiti is a Dutch marketing firm that has been successful in getting companies like Starbucks and Becks to advertise this way. Should it be illegal if it doesn’t harm the environment? Or is it the aesthetics that count?
Source: Reverse Graffiti