Microclimate and microbial monitoring, a case study: the Oratorio dei Falegnami in Palermo

Abstract

The following study has been carried out during the restoration work of the polymateric sculpture “Immacolata Concezione” located inside the chapel of the Oratorio dei Falegnami in Palermo. The manufact, a typical example of Trapanese (Sicily) craftsmanship (18th century) made by pieces of fabric, soaked in animal glue, applied to an inner structure, finished with plaster and painted. The main damages were paint losses and flaking all over the surface on textile backing, due to the indoor microclimatic conditions. After the conservative restoration, in order to prevent such damages, the microclimate monitoring was performed in two steps. First, the presence of temporal and spatial gradients has been verified by portable thermo-hygrometer (temperature, relative humidity) and measured at a height of 1 m (12 sampling points), during one hour (from 12.00 p.m. to 13.00 p.m.). Then, two data logger were placed from February to the March 2015. Microbial contamination of both aerosol and sculpture surface has been assessed using sterile swabs and inoculating agar medium. The aerosol sampling has been performed by passive method, (measuring the rate at which the micro-organisms settle on surfaces) exposing the agar of Petri dish for one hour to collect aerosol bio-particles. Morphological recognition of bacteria and fungi colonies was performed by optical microscopy analysis. Thermo-hygrometric analysis showed irregular variations of the parameters with daily fluctuations, while the analysis of air and surface contamination did not show a critical situation. In conclusion, the results were relevant to define a suitable strategy for the conservation and sustainable fruition of this manufact