J.CAC VOLUME 44 (2019)
Performance Testing of Anti-graffiti Coatings for Painted Outdoor Murals in Canada
Outdoor murals are sometimes defaced by graffiti that introduces unwanted painting, tagging or “bombing” on the surface. The purpose of this study was to compare the performance and handling characteristics of ten anti-graffiti coatings and five acrylic varnishes that could potentially serve as anti-graffiti barriers on outdoor murals in the Canadian climate. A selection of both permanent and temporary coatings was made after carrying out a literature search for products available in Canada. Painted test panels were prepared with acrylic latex exterior house paint, following the procedure of a muralist. Protective coatings were applied to each panel based on manufacturers’ recommendations. The panels were aged outdoors for two years, then marked with graffiti materials. Solvents and other methods were used to reduce or remove graffiti marks to determine which coatings provided good protection to the underlying paint. The overall performance of the coatings was assessed on the following criteria: initial and aged appearance (gloss, dirt pickup, colour change), ease of coating application and handling, effectiveness as a graffiti barrier, and ease of local reapplication after graffiti removal. Observations were documented by photographs, videos and notes using customized forms and a standardized rating system. Quantitative gloss and colour measurements were made during the first three years of outdoor exposure to chart the rate and amount of visual change. Of the fifteen coatings studied, many performed adequately as graffiti barriers, but three products were deemed best overall because they performed well across the entire range of the assessment criteria. These included a double-component acrylic varnish system and two aqueous, wax-based anti-graffiti coatings. Overall, increasing the number of applied layers did not adversely affect the appearance of the coatings, and additional layers gave some coatings better resistance to graffiti, as well as protecting the paint layer from solvents and other cleaning methods required for graffiti removal.
Download: JCAC44 O'Malley & Binnie