The relevance of monitoring the microclimate in museums. The case of Colle del Duomo in Viterbo

Abstract

Microclimate monitoring is a fundamental step in preventive conservation and must be taken into account in the planning of museum expositions and in other confined environments, as stated by international standards produced by the technical body CEN/TC 346. This contribution synthesizes the results of extensive monitoring campaigns in the Museum of Colle del Duomo, a diocesan museum located in the important complex of the Papal Palace of Viterbo (Central Italy). The museum contains different kinds of religious objects such as reliquary busts in wood, papier-mâché and metals, sacred clothes, panel paintings, gypsum ‘modelli’, and also archaeological artefacts. This wide variety of materials makes particularly difficult to maintain environmental parameters, such as light, relative humidity and temperature, within the ranges of values recommended by the Italian and European standards for Museum conservation. However, the monitoring campaigns allowed to know the most critical situations and to intervene with solutions aimed at mitigating the effects of microclimate on the artefact materials. Three main rooms were monitored for one year: the Sacred Vestments room, the papier-mâché reliquary room and room of Baroque wall paintings with the beautiful wooden choir in a closed area of the Cathedral, immediately adjacent to the Museum. The continuous monitoring was performed by means of portable data-loggers. Irradiance (W/m2) and illuminance (lux) were measured only in the Sacred Vestments room, being textiles highly sensitive to light.