An anti-graffiti product is a protective coating which is used in graffiti-prone regions for the prevention of irreversible adhesion of graffiti to the substrate. Please be aware that “anti-graffiti” will not mean that treatment or the coating prevents graffiti it means that graffiti can be removed easily. The broad variety of painted and unpainted surfaces graffiti is applied to and the plethora of graffiti media determine the resistance to graffiti removal.
Graffiti resistance of a substrate is influenced by:
- Whether it really is bare (unpainted), painted or treated
- The kind of coating on its age, and the substrate
- Components of the graffiti medium (merchandise formulation), and its age
- Frequency of removal
- The substrate profile (smooth or rough)
Substrate – Painted, Treated or Unpainted?
Unpainted surfaces, including brick, flagstone, concrete or lumber, are normally quite porous, and hence allow graffiti media to penetrate the pores, making the graffiti tough to remove. Replicated cleaning with ultra high pressure water wash, wire brush, abrasive blast and other mechanical means of removal are not constructive, while the usage of chemical strippers and solvents can drive pigments and stains deeper into the substrate.
Surface treatments penetrate the surface are mostly undetectable and pores. Some are successful in repelling water and water based graffiti media, but not other kinds of graffiti. Others, however, can repel the adhesion of most types of graffiti as well as dirt and spills.
Types of Coatings and they are Affected by Graffiti
Single pack paints, whether solvent-borne enamels or water-based acrylics, have poor resistance to the solvents within graffiti and in the graffiti-removing agent, causing them to soften, wrinkle or dissolve. Dyes penetrate and stain single packs rather readily.
Two-pack paints, being much more highly cross linked and porous, are way more chemically resistant and therefore will be way less affected by solvent present in graffiti and graffiti -removing agents, and are much less likely to absorb colours.
The most powerful anti-graffiti paints are two-pack, solvent-borne polyurethanes. These offer highly cross-linked coatings with excellent solvent-resistance, resistance to graffiti-removing agents, low porosity and high gloss degrees.
A lower polish degree offers an improved key for the graffiti to stick to and an elevated surface area. Graffiti- removing agents cannot always reach the miniature troughs at first glance to effectively remove the graffiti, leading to graffiti deposits and shadowing.
The colour of the anti-graffiti coating can affect the perception of how nicely graffiti continues to be removed. Mid-toned, neutral colours like mid gray or sandstone show less shadowing (if present) than lighter or brighter, cleaner colours, and therefore are favored for places often assaulted by graffiti.
Age of the Coating
The longer the paint has been applied, the greater the cross-linking, and hence the better the graffiti resistance. It is essential to ensure that the newly applied paint is shielded from graffiti attack until it has fully cured. Single pack paints, particularly enamels, tend to chalk with time, creating a porous surface that absorbs more graffiti.
Graffiti Media Used
The graffiti medium used, heavy-duty or whether an aerosol spray can marker, will differ from others with regard to difficulty of removal on account of materials present in the formula. Formulation differences also occur between different brands of the one generic type of medium used, leading to differences in ease (or difficulty) of graffiti removal.
Higher quality brands will usually feature exceptional raw materials such as more permanent resins, and more fade-resistant pigments. Low quality brands may tend to sag or run more, causing thinner, more easily removed graffiti, or have poor coverage and may include lower levels of pigment and resin. Then again, the running and sagging of the graffiti medium may result in the graffiti covering a greater area and consequently requiring more effort to remove.
Aerosol spray cans are usually solvent-borne enamels or water-based paints, enamels being far more common. The organic solvent component of enamel spray paints can affect the present single pack coatings on the wall; depending on the combination that is solvent, the effect can vary from minimal softening. The underlying paintwork craze, may crack or blister.
Heavy duty markers depending on xylene, toluene or other harsh solvents can affect paintwork also. Occasionally the surface can be stained by dyes that are invasive, although paintwork do not affect to any amount.
Some spray paint pigment colours and heavy duty marker ink colours can permeate and concrete stain coatings that are particular permanently making it impossible to entirely remove the graffiti.
Other colours don’t permeate until they come in touch with a solvent contained in the graffiti-remover; the solvent dissolves or disperses the pigment or ink and takes the colour into the paintwork over a wider area in relation to the first graffiti. Often this appears as “shadowing”, which only becomes evident after most of the graffiti has been removed.
Age of the Graffiti
The more the graffiti was left on the surface, the more powerful its adhesion to the surface. Enamel established graffiti (eg spraypacks) crosslink as they age, becoming tougher and more difficult to remove. As coalescing agents and other volatile components evaporate in the paint, acrylic paints also harden with time. In all instances, removing graffiti soon after it has been applied is significantly easier than removing graffiti that is aged.
Removing graffiti shortly after it’s been implemented has other advantages also:
– There is normally not as much graffiti to clean – graffiti will multiply
with time as graffitists easily recognise property that’s infrequently cleaned, and
– Labels attract more tags. Regions without tags are of less interest to graffitists
than areas where tags abound, as each is keen to “mark their lands”