Graffiti Removal on Historic Brick: Assessing Micro-Abrasive Cleaning Performance and the Challenges of Preserving Surface Texture

Removing graffiti from porous masonry remains a significant conservation challenge, in part as spray paint may penetrate the pores of the material. Historic brick is particularly vulnerable due to its softer texture and higher porosity compared with dense stone or modern brick, which increases the risk of paint absorption and surface alteration during cleaning. Micro-abrasive cleaning employs fine particles at low pressures to provide a relatively controlled method that minimizes direct chemical exposure, discoloration, and excessive material loss. However, the effects of this technique on historic brick have not been thoroughly investigated. In this study, cleaning performance is assessed through analyses of color and surface texture changes conducted before paint application and after cleaning trials. The extent to which the original fire-skin remains serves as an additional key indicator of the aggressiveness of this cleaning method. By integrating instrumental measurements with visual and tactile assessments, the study provides evidence-based insights into graffiti removal on historic brick and underscores considerations for conservation cleaning of sensitive masonry surfaces.