J.CAC VOLUME 47 (2023)
Evaluating the Suitability of Two Sacrificial Anti-Graffiti Polysaccharide Coatings for Use on Outdoor Contemporary Murals
This research investigates, through laboratory testing, the suitability of PSS 20 and APP S, two sacrificial polysaccharide-based anti-graffiti coatings, for the protection of outdoor contemporary murals. The properties of these coatings, as described by their manufacturers, are promising for conservation applications: easily reversible, clear, non-toxic, biodegradable and compatible with most surfaces, including painted ones. Primed and painted clay bricks and cement board surrogates were prepared and coated with PSS 20 and APP S. Some surrogates were left unaged while others were aged artificially for 9 and 29 hours. All surrogates were subsequently marked with spray paint or permanent felt marker. The efficacy of graffiti removal using pressure washing on aged and unaged coated surrogates as well as the impact on the painted substrates were evaluated using colorimetry and microscopy techniques. Both coatings showed promising results on the unaged and 9-hour aged surrogates in terms of ease of removal of graffiti and minimal alteration of the substrates’ colour. When artificially aged for 29 hours, the coatings were significantly less effective in protecting against graffiti. The coatings are easily reversible with warm water and moderate pressure with no or very little damage to the surface (depending on the texture) provided they are dampened with water and allowed to swell beforehand. Since this research was undertaken, PSS 20 has been used successfully in our private practice for the protection of outdoor sculpture and public art made of stone, metal and varnished wood. This experience has confirmed that a polysaccharide-based anti-graffiti coating can provide appropriate protection for heritage surfaces under threat of graffiti vandalism.
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