Graffiti removal on external thermal insulation composite systems through chemical-mechanical methods: A feasible protocol?

External thermal insulation composite systems (ETICS) have been widely adopted for improving the thermal comfort of building facades. Although these systems are commonly subjected to vandalism in urban areas, no protocols for the removal of graffiti on ETICS have been yet systematically defined. In this work, aerosol graffiti sprays (blue and silver) were applied on ETICS with different compositions and then removed through chemical (alkaline graffiti removers) and/or mechanical methods (brushing). The moisture transport properties and the aesthetic features of ETICS specimens were characterized prior and after graffiti removal, aiming at assessing the effectiveness and compatibility of the cleaning action. Results show that the effectiveness of graffiti removal strictly depends on the type of aerosol graffiti spray and of ETICS surface. The use of chemical or mechanical methods can lead to severe damage on systems with EPS-based thermal insulation layer and/or silicate or lime-based finishing coats, with an increase of the water absorption and alteration of the chromatic coordinates.