Description of Tasks

The project will involve preparation, exposure and subsequent evaluation of damage dosimeters. Exposure will occur at a number of sites of varying conditions of air quality, where air composition has been evaluated or will be as part of this project. Specific locations within sites will be selected in close collaboration between scientific and curatorial staff. Sites within four European countries have already been selected, and these include both Northern and Southern European countries and some locations which had been tested in previous projects but where environmental conditions had not been fully evaluated. They represent both urban and semi-rural conditions and provide examples of both highly and less highly visited places. Monitoring of microclimate conditions will be performed in the vicinity of selected paintings and particularly where recent problems have been reported by curators and conservators. The effects of damage during transportation of artworks, will also be investigated, where necessary.

Damage assessment will rely on the extensive in house database of physicochemical changes in paint tempera dosimeters which have been quantified with respect to artificial light and natural ageing. This database will be extended to provide information on their response to various levels of pollutant gases. Work will also include coating piezoelectric quartz crystals (PQCs) with paint tempera and artists' materials, such as varnish. The change in the coating characteristics will be read as a shift in the oscillation frequency of the crystal using a frequency meter. The relation of frequency shift to damage will be calibrated and coated piezoelectric crystals will be exposed to atmospheres of known light, pollutant levels, relative humidity and temperature. Eventually the frequency shift could be converted to a voltage to allow for continuous logging of damage assessment data. The rationale for a European project is that environmental quality and development of microclimates in collections is strongly affected by local climates and so monitoring of sites in several countries will provide a diversity of conditions ensuring a rich database for conservators.

The work packages are linked by one common aim, that of assessing the potential of indoor environments to increase levels of damage to objects, and possibly to alter the path of previous mechanisms of natural ageing. To achieve this aim novel damage dosimeters will be prepared and exposed at a range of sites in conjunction with a detailed environmental monitoring programme which includes measurement of humidity, temperature, light and pollutant levels (NO2, SO2, O3 and HONO).

The work plan is divided into five work packages which cover the scientific development and preventive conservation aspects of the project.

The selection of sites and installation of monitoring equipment is detailed in work packages 1 and 2. These refer to locations in Southern and Northern Europe respectively. Work package 3 focuses on the preparation and supply of paint based dosimeters on a polymer substrate to site exposure. It also includes preparation and laboratory evaluation of novel coated piezoelectric quartz crystal (PQCs). This is necessary to evaluate the suitability of the various proposed coating materials, and in particular their long term performance. There is also the need to evaluate the chemical sensing ability of the coating and how this produces a change in the oscillation frequency of the crystal in response to artificial ageing regimes. This work represents the novel technological aspects of this project and is covered in work package 4, together with the chemical analysis procedures. Methodologies for such analysis have been developed in a previous project. The combination of colour measurements together with mass spectrometric, thermoanalytical and spectroscopic techniques have yielded valuable markers of the physicochemical state of coatings.

Work package 5 links together environmental monitoring data obtained at the sites with the chemical assessment of damage of the coating (in terms of measurable chemical markers) and resulting frequency shift parameters from the PQC coated dosimeters. The use of pattern recognition techniques in conjunction with arrays of sensors will enhance the extraction of useful data and minimise background interference effects. It will also provide in future a method for assessing cumulative damage in terms of a direct readout which can be made in house, rather than requiring sophisticated chemical analysis.

Timing of Tasks

Project Workplan