graffiti problems - clones are people two!

Architect's memo 41: October 1984

From the original terse messages scratched on the walls of the urinal in Taihape to the dynamic outpourings on the walls of the Wellington bus terminal, the 'art' of graffiti grows more intrusive every day. Whatever one's reaction to it is, and some of it can be very witty, it can not be denied that it defaces buildings and results in spiraling removal costs.

The two major factors to be considered in graffiti damage are the kind of vehicle used for the graffiti and the type of surface to which it is applied. Modern technology has supplied the graffiti artist with a formidable array of raw materials with which to pursue his/her craft; in the vanguard of which is the versatile spray bomb. Based on high polymer technology and durable pigments these materials are not easily shifted.

It is stating the obvious when saying that the smoother the surface the more easily cleaned it is, but it should be borne in mind in the war against graffiti. Unsealed porous surfaces such as brick, concrete and concrete masonry, unpolished stone etc can accept the graffiti medium within the pores of the surface and even complete removal of the graffiti on the surface still leaves its indelible message. Only removal of the surface layer by sandblasting or the like can completely remove deeply penetrated graffiti.

Coatings have a role to play in combating graffiti by providing smooth sealed surfaces which prevent penetration. As the coating then becomes the layer which receives the graffiti, it in itself must be able to resist the cleaning agents and strong solvents used to remove the offending messages. This necessitates the use of very hard, densely cross-linked coatings such as specially formulated two-pot epoxies or polyurethanes with solvent resistance as their chief parameter.

Solvents used to clean off graffiti need to be strong enough to remove the graffiti without affecting the underlying coating. They also require an evaporation rate that is not too fast otherwise the graffiti becomes smeared over the surface and re-dries as the solvent evaporates. The ideal cleaning solvent will remain wet long enough for the surface to be wiped clean.

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