Compatibility matters: assessing the risks of built heritage cleaning

Today, heritage conservation is a discipline torn between the objectivity of its material questions and the subjectivity of its stakeholders and practitioners, inherent to the fact that conservation is, first and foremost, a cultural act. Most current conservation perspectives advise for (conservation) decisions to be based on the significance of the heritage object. Following this approach, different management tools have emerged to assist conservation at site, local, national and international levels. Quite the opposite, in what concerns interventions, conservation is still largely viewed as an objective material problem, and decision-support tools at this level are still mainly focused on performance assessments. An exception to this rule is the Eight-step Planning Model, complemented by the (In)compatibility Assessment Procedure, proposed by Delgado Rodrigues & Grossi, which attempts to bridge the gap between the macro and micro levels of heritage conservation planning. Compatibility has been gathering momentum as a conservation principle, but it has been mostly dealt with from a purely material perspective and is still insufficiently defined, especially in scopes beyond product testing. Borrowing from the aforementioned (In)compatibility Assessment, the research presented herein argues that compatibility is an adequate operative concept to assist decision making and guide conservation interventions. The key for using the principle of compatibility at this level of heritage conservation is to link it to the significance of the (conservation) object. This is demonstrated by proposing a procedure for the planning of built heritage cleaning based on the assessment of its risks towards significance; using risk analysis as a development tool, this procedure intends to frame the subjectivity of decision making in heritage cleaning. From this research, it follows that the principle of compatibility may constitute a valuable bridge between the objectivity and the subjectivity of heritage conservation.