The diagnostic study of the plaster replicas of the Trajan's Column conserved at the Museum of Roman Civilisation (Rome)

The management of indoor microclimate in museums has recently received growing attention. Museum climatology and the mechanism for the degradation process, defined as a result of progressive and cumulative decay, depends on environmental variables and their changes. In fact, temperature and relative humidity gradients are often the main causes of chemical and physical decay of artefacts. This research focuses on assessing the state of conservation of 34 gypsum-based plaster replicas of Trajan’s Column at the Museum of Roman Civilisation and on the microclimate monitoring of Room LI, where they are conserved. The decay assessment of the studied plaster casts was performed using a multidisciplinary analytical approach to characterize the constituent materials and to identify the main degradation patterns by i) on-site investigation with non-destructive methodologies; ii) chemical and petrographical characterization on collected micro samples. Microclimate variables (temperature, relative humidity and dew point) were measured along seven months to define the actual environmental conditions and the response of the materials to the microclimate.