Conservation of Cultural Heritage
Head: Dr. Cristina Sabbioni

The activity performed by the research group working on Conservation of Cultural Heritage is focused on the development of the atmospheric sciences and climate to the protection, conservation and valorisation of Cultural Heritage.

Atmosphere- Material Interactions
There is a general agreement that atmospheric pollution is the main agent responsible for the damage encountered on monuments and historical buildings in urban areas. Soiling phenomenon appears to be accelerating and this can be easily observed in the continual blackening and repetitive restoration of monuments and historical buildings. During 2002 the research activity was mainly focused on the role of black patinas in stone decay and on the relationship between elemental carbon particle atmospheric contents and monument blackening rates developed in the context of the European Project CARAMEL. The experimental work performed during 2002 included measurements of soot particles in aerosols and in patinas including the two different fractions organic and elemental carbon in selected target sites (i.e. Milan, Florence, Rome, and Venice in Italy, Paris in France, London in UK and Seville in Spain). A new methodology for carbon analysis in patinas was developed and applied in all samples analysed. The preliminary results achieved give evidence that elemental carbon (EC) is a major component of the European urban aerosol phase and heavily (if not solely in some situations) related to traffic activities showing intra-site important variability in relation with meteorological conditions (wind, urban boundary layer height) and time of the day (traffic peaks). EC as soot tracer is also the dominant component in black crusts, but its abundance also displays an important site to site variability and may reach 50% or more of the total non carbonate carbon. In Sevilla, organic tracers show the overwhelming contribution of diesel bus exhausts for soiling, as shown by the parallel analyses of crusts, environmental aerosols and bus exhausts.
This project aims to contribute to the understanding of black crusts growth in multi-pollutant influenced atmosphere, by focus on the key role of carbon particles as a vector of pollutant transport, deposition and transformation when embedded in patinas.

Microclimate
In the course of centuries, materials used in artworks loose elasticity and reversibility, so that any departure from the original conditions is dangerous and has a cumulative effect that, in the long run, becomes visible. The recent church heating, mainly operated at broken times, constitutes a tremendous challenge for conservation of this extremely important cultural heritage. Despite an extensive literature, deterioration mechanisms are not fully known.
For protecting artworks in churches, a novel heating system has been developed which is able to contain heat just in the area where people stay. The EC project FRIENDLY HEATING concerns the study of the internal microclimate and the response of wooden artefacts to the temperature and humidity forcing, the advection and diffusion of the indoor air masses, the transport and deposition of airborne pollutants, the simulation of the convective cells over the benches, the human benefit under different conditions, the construction and set-up of the heating prototype.
Furthermore within EC VIDRIO project a study focused on the improvement of methods and technological systems in order to control and reduce damage of stained glass protected with glazing and not protected, exposed to climatic influences, air pollution and biodeterioration was developed. The environmental impact on the stained glass in target sites (i.e. Sainte Chapelle, Paris and Cathedral of Cologne) was particularly studied as a consequence of the daily and seasonal cycles of the climatic and other environmental variables (e.g. visitors, heating and air-conditioning systems, infiltration of polluted air from outside). In particular the local climate (air temperature, dew point, relative and specific humidity, ventilation, radiation) and the internal microclimate concerning the stained glass under study (glass temperature, spread above the dew point, condensation on the panel and time of wetness, ventilation) was monitored with automatic devices and special intensive field surveys. The final goal is to give a final judgment on the goodness of the double glazing as a solution for a better conservation of stained glass from all the point of view (physical chemical and biological), to provide a methodology for the best management of these buildings and identify the thresholds of danger to preserve stained glass.

Biodeterioration
The conservation of artistic and cultural assets must take account of biological factors also i nvolved. The recent activity was mostly focused in the set up of system for the assessment and remote control of indoor microclimate to implement sustainable preventative conservation strategies toward biodeterioration. Statistical data on the appropriateness of current environmental control systems were collected. This will provide strategic tool for cultural heritage management that can be applied broadly to a diversity of museums, galleries, libraries and archives.