Anti-graffiti coatings can be invisible to the naked eye. There are two different categories of anti-graffiti coatings. The first, sacrificial coatings, are applied to a surface and then removed when graffiti is applied. The surface underneath will be left clean and a new sacrificial coating can be applied.  The other type of coating are permanent coatings that prevent graffiti from adhering to a surface in the first place.
Newer coatings are made of charged polymeric materials that form a gel on the surface of the building or substrate.  Some of the most important characteristics of anti-graffiti coatings are:
* Sufficient adherence without damage to substrates
* Hydrophobicity (water repellence)
* Environmentally friendly composition and processing
* Resistance to UV aging and weathering
* Good cleaning efficiency