An Approach to the Evaluation of Cleaning Methods for Unglazed Architectural Terracotta in the USA

The safe and effective removal of disfiguring atmospheric soiling from brick and unglazed architectural terra cotta is a problem well known to building specialists. While limited research has been conducted on the study and repair of glazed architectural ceramics, very little recent work has addressed the characterisation and analysis of unglazed architectural terracotta, the physicochemical nature of soiling mechanisms, or the short- and long-term effects of commercial cleaning methods currently employed. In addition, an over-emphasis on cleaning efficacy, along with the meteoric rise in the availability of untested chemical and mechanical cleaning systems, has led to the disfigurement and surface damage of many terracotta buildings, permanently altering the visual and protective qualities of the material and potentially jeorardising the overall weatherability and performance of each building's skin.