Anti-Graffiti coatings are found in two basic categories: Permanent and Sacrificial.

Sacrificial Coatings, almost without exception, are water-based. Some cause minimal darkening of concrete, etc; as well as being able to protect - to an extent - more sensitive surfaces such as acrylic or plastic paints, sign writing, etc.

They are less noxious in use and "environmentally friendly", as well requiring less specialised knowledge and expertise in use.

The downside is that they "sacrifice" themselves to the cause of graffiti removal. The anti-graffiti coating itself is removed chemically, taking the graffiti with it. The sacrificial coating therefore may provide protection to the surface from graffiti but not necessarily from the chemicals used to remove it. Plastic sign writing paints, for instance, are likely to be removed along with the sacrificial coating, as they are sensitive to the same types of chemical removers.

The system also opens a "window of opportunity" to the graffiti artist. After the coating and attendant graffiti is removed, the surface is unprotected until the coating is reinstated. In many cases, this involves the passage of one or more nights, and at the very least several hours during which the surface is totally unprotected and may be more permanently vandalised.

This is quite apart from the cost involved in reapplying the coating to the surface every time it’s "hit".

Lastly, the chemicals used for removal are normally smelly, noxious, caustic, and in many cases, toxic. A number of commonly used removers cause severe burns on prolonged contact with the skin. These chemicals are of necessity spread around liberally, and then hosed away into the surrounding countryside, or at best down storm drains, usually with a very limited local water supply preventing the required degree of flushing and dilution to render them safe.

Permanent Anti-graffiti Coatings are normally two-pack polyurethane, epoxy or so-called "iso-free urethanes". These are thinners based and present a number of problems, including risks to applicators and bystanders from fire and explosion; health risks; environmental concerns with V.O.C. emissions, waste disposal and cleanup; plus the inevitable wastage that is implicit with any two-component product. They are generally not suitable for application over existing paint systems or sign writing, and will substantially change and darken the appearance of stone and masonry surfaces in particular. Some types will darken and "yellow" on exposure to sunlight.

At their best, they provide protection for the substrate from multiple attacks and subsequent removals using very aggressive chemical cleaners and high-pressure water blasters, without the need to repair or replace the protective coating.

1: VanGuard10 is suitable for sealing rough-cut or dressed natural timber against graffiti in sheltered situations, but will not protect unpainted timber from the effects of sunlight (bleaching and surface degradation) or full weather (splitting, cracking, wet & dry rot), and, as such, should not be considered a finish for exposed bare timber. Ongoing exposure to weather will cause degradation of the timber surface and result in eventual delamination of the coating.