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, sidewalk 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.

Some examples below: