Developing coatings that are resistant to marking and staining is one of many high-demand R&D projects for paint manufacturers. Graffiti removal costs municipalities and businesses millions of dollars every year, so painting contractors are often asked for coatings that resist marking and are easy to clean.
The Graffiti Test
The coatings industry has adopted a standardized test to determine the graffiti resistance of a given finish. The test is called the Standard Practice for Determination of Graffiti Resistance (ASTM D 6578 – 00), and measures the ease of cleaning graffiti from a coated surface.
First, the laboratory technicians paint a surface according to manufacturer’s recommendations, and then expose the surface to both natural and simulated aging. Once the coating is ready, the surface is marked. Typical graffiti materials are used for the test, include spray latex, epoxy and enamel as well as colored markers. After application, the material is left to dry for 24 hours.
Once the material is dry, a series of cleaning procedures, from least intensive to most intensive, are used to remove the markings. Each of the cleaning methods is assigned a level, with Level One reserved for the most gentle cleaning method (a dry cloth) and Level Five for the most intense cleaning method (methyl ethyl ketone, MEK). The testers note the ability of the coating to retain the marking color, lose gloss or change color as each cleaning method is attempted.
The coating is assigned a cleanability level for each type of graffiti medium used. Thus a coating might be Level One against markers, but Level Five against spray enamel.
Coming Up: Graffiti Resistant Paints