Methodology to evaluate the state of conservation of historical plasterwork and its polychrome to promote its conservation

Abstract

This work presents a methodology for the assessment of ancient plasterworks based on traditional inspection techniques, such as organoleptic tests and chemical characterization, and also on digital tools, such as photogrammetric surveys, thermography images, and measurement of ambient conditions with thermohygrometers. This method allows not only defining the alterations detected and establishing the state of conservation but also digitalizing the plasterworks to preserve the heritage and replicate the model if necessary (i.e., replacement of a detachment piece), drawing a hypothesis of the original hidden design of the plasterwork, and conducting a chronological study about the polychromies used over time. In some cases, the assessment has shown that the liming and repolychrome interventions to which plasterworks have been subjected and the powdery state of some areas do not ensure the possibility of the complete polychromy restoration, only its preservation by taking conservation and maintenance measures.