AIC's 45th Annual Meeting

This research comparatively investigates the effectiveness and visual impact of six commercially available sacrificial anti-graffiti coatings for use on outdoor marble heritage. Sacrificial coatings are reversible barrier films that can protect vulnerable surfaces from damage resulting from this type of vandalism. Graffiti materials such as spray paint and the ever popular Sharpie marker seep easily into porous marble surfaces to create stains (called ghosting) that are difficult to safely remove. Cleaning processes to completely remove ghosting can result in surface losses. An ideal coating preserves the natural color, gloss, texture, and integrity of marble substrates and adequately aids in the complete and safe removal of graffiti. 
The coatings evaluated in this study are PSS 20, APP-S, Protectosil AQUATRETE®SG®, "World's Best” Graffiti Coating, Graffiti Melt, and Graffiti-Pruf. Each were either chosen due to notable performances in other studies, or their recommendation for use on other types of stone/masonry. Red spray paint and black Sharpie marker were applied to the samples and removed according to the coating manufacturer's instructions. To evaluate the coatings' aesthetic impact and effectiveness in facilitating graffiti removal from Royal Danby marble samples, this study uses data gathered from colorimetry, glossimetry, laser profilometry, contact angle goniometry, gas chromatography-mass spectrometry, and visual assessments. Half of the samples were placed in a QUV accelerated weathering chamber for 800 hours before attempted graffiti removal to assess the long-term effectiveness and reversibility of the coatings after artificial aging. Surface pH levels of the coatings before and after artificial aging and film thickness were also measured. This suite of tests aims to aid conservators caring for outdoor marble heritage in graffiti-prone locations in selecting an appropriate and accessible sacrificial coatings for their needs.