The Nordic Method: Performance Tests for Protective Sacrificial Coatings on Mineral Surfaces

The paper describes the development of a performance test for sacrificial coatings used on mineral surfaces, in particular for protection against graffiti. The method considers both the type of surfaces and of possible graffiti paints, and specifies the method as well as the evaluation techniques for the performance of the protective coating. The purpose of the project was to develop a Nordic test method for evaluation of the performance of anti-graffiti coating on different mineral surfaces such as natural stones, bricks and concrete. The performance of the anti-graffiti was determined by comparing the colour and gloss changes of reference surfaces versus anti-graffiti treated surfaces after cleaning of the applied graffiti paints. It was demonstrated that different mineral surfaces responded differently to the graffiti protective coating. This confirmed the assumption that porosity, type of material and surface finish influence the behaviour of the applied coating. Consequently, mineral materials require different approaches, i.e. different anti-graffiti and application techniques. However, there are graffiti paints that penetrate through the graffiti protection coating which means that further development of protective surface coatings is needed. The cleaning of graffiti must be performed by a professional team that has knowledge about the properties of the surface and its vulnerability to both water pressure and chemicals.