Graffiti is the deliberate defacement of property without the owner's consent. Graffitists use aerosol paint cans most commonly, as it combines paint and applicator and is easy to conceal, although heavy-duty felt-tip markers, paint and brush, large crayons, lipstick and even blood are also used. In fact, just about anything that can quickly leave a mark can be used to graffiti property.
Graffitists are attracted to broadwall areas with high visibility, particularly those that are rarely cleaned, as these walls present a more permanent showcase for their "art" or tags. It is a well-known fact that where graffiti is removed almost immediately, subsequent graffiti is much slower to appear, as such areas are not deemed to be worth the effort. Also, tags are more likely to appear on walls already carrying tags, as the ego of the graffitist will not allow a rival's tag to remain unchallenged.
We often hear a coating being described as "anti-graffiti", referring to any coating that is used in graffiti-prone areas for the purpose of preventing the permanent adhesion of graffiti to the substrate. The term "anti-graffiti" can be misleading, however as it implies that the coating somehow prevents graffiti from being applied to it. If only this were possible!
There are generally three types of coating used in protection of surfaces against the adhesion of graffiti:
Sacrificial coatings are usually clear, thin film wax emulsions applied to the surface to be protected. When defaced, the sacrificial coating is usually hosed off with hot water and a new coating is immediately reapplied.
Semi-sacrificial coatings are usually high build acrylics that shed a few microns of the top layer each time the graffiti is scrubbed off. After several cleaning cycles, and before the coating is completely worn away, a future coat or two are reapplied to restore the original appearance.
A permanent graffiti-resistant coating is a coating that resists permanent damage or discolouration from the application of graffiti, and is also resistant to the harsh graffiti removal agents used to clean the surface. Such coatings are usually fairly glossy and chemically inert and thus minimise the ability of the graffiti to penetrate or adhere to the coating and so make subsequent removal easier. The permanent graffiti resistant coating is the easiest to maintain, as it withstands repeated cleaning using conventional graffiti removal cleaners.