Title: Conservation Science and Changing Colours ‐ Approaches to measuring and managing change
Abstract: Colour in paintings and works of art is of fundamental importance in conservation, as is the understanding of the ways that pigments are used by artists to create different optical effects in paint. Part of conservation is technical study which involves understanding paint application, the layering pigments in a binding medium, and the role of the varnish or surface coatings – and work at The Courtauld Institute of Art has played a fundamental role in the understanding of the technology of easel paintings and wall paintings. My talk will highlight new research in the use of imaging and spectroscopic techniques for the visualization and mapping of pigments that will include wall paintings in India, Italy and Sweden. A vast range of pigments and layer structures are found in easel and wall paintings, from the single layers to multiple and complex mixtures found in Cypriot Byzantine wall paintings. Conservation is also faced with challenges related to pigment deterioration – which may often have a strong impact on the appearance of paintings and the colour of pigments. Indeed, many factors can affect paintings and the stability of pigments – from photooxidation as a results of light exposure of red and yellow organic lake pigments, to chemical reactions between pigments and binding media, to the degradation of modern pigments. Recent research can shed new light on the mechanisms behind colour change – and may suggest how we may be able to prolong the life of paintings. Here analytical techniques are of fundamental importance to reveal molecular changes on the microscale. Examples of research on cadmium and copper-based pigments from historical samples of easel and wall paintings and works by Picasso and Leonardo da Vinci will be shown.