Chemistry, Microstructure, and Rheology of Tempera and Oil Paints and its Relevance for the Paint Application Process and Painting Texture
Artists’ paints are complex, multiphase fluids including inorganic pigment particles, dispersing agents, organic binders, flow control additives all dissolved or suspended either in water, oil or in a mixture of hydrophilic and/or hydrophobic liquids. Often these mixtures exist as emulsions and the above-mentioned ingredients may be either included in the disperse phase or in the continuous phase. Not only the application properties of artists’ paints, but also the appearance and texture of the dry paint strongly depend on the flow behavior of the wet paint. These flow properties cannot be inferred from the chemical composition of the paint alone but depend on the volume fraction as well as the size and shape of the pigment particles, their surface properties, the interactions among the ingredients and the finally resulting microstructure of the multiphase system.
This study addresses how the wet paint structure transforms into the dry paint film and how binder analyses of real artworks must be interpreted and thus help to improve efficient and targeted conservation strategies for unique and invaluable artworks. The project includes aspects of analytical chemistry, rheology, colloid chemistry and is performed in collaboration with three research groups at University of Pisa, Karlsruhe Institute of Technology and Bavarian State Painting Collections – Doerner Institute.