The basic concept of this project is to identify and then use the changes which occur in the chemical and physical properties of traditional paint media both to indicate and integrate the effects of environmental conditions on paintings. To achieve this aim, test paint films are being prepared in accordance with traditional artists' recipes. Changes in material properties are monitored using a combination of non-invasive spectroscopy, microsensors, thermoanalytical techniques, and microscale analytical mass spectrometry for molecular structure analysis. The test strips are calibrated by exposure to controlled environments (light, temperature, relative humidity and noxious gases) and alterations in their properties are quantified. This provides information on the nature and rate of change at the molecular level and a data base for evaluating the molecular monitoring strips after their exposure in the field. Field sites have been selected and include various locations in the Tate Gallery (UK), Sandham Chapel (Burghclere, UK), the Uffizi Gallery (It) and the Rijksmuseum (NL). Environmental conditions of some of these locations are being evaluated at present using the glass sensors described in project EV5VCT92 0144. Small piezoelectric quartz crystal humidity sensors will be installed to determine localised variations in relative humidity and temperature on [1] Stanley Spencer paintings in Sandham Chapel and [2] Giotto's "Madonna di Ognissanti" in the Uffizi Gallery. In addition novel coatings using picture varnishes are being applied to similar piezoelectric quartz crystal sensors to evaluate the effects of environmental impact on the chemistry of varnishes on paintings. Data are also being collected on the nature of chemical and physical changes in varnishes and paint media in actual paintings at the molecular level.