Watching paint dry: Assessing the curing and aging of modern oil-based paints

The mech. properties of artists' paint films have been the subject of few investigations. Their study is nevertheless important because of its implications for the deterioration, handling, storage, and treatment of paintings. Tensile strength measurements provide insight into the mech. properties of paint strips, but the sample sizes required for these tests limit their applicability to actual artworks. In this partnership between the Art Institute of Chicago and Northwestern University, we explore the use of two techniques for studying the mech. behavior of artists' paints as well as model systems of pigment-filled and unfilled alkyd resins. Firstly, we use a quartz crystal microbalance (QCM) to measure the phys. properties of the model systems during curing in real time. The technique is sensitive to both mass changes and the dynamic shear modulus, in ambient conditions as well as at elevated temps. Secondly, nanoindentation is employed to investigate the properties of the same paint films as a function of curing time, providing both hardness and elastic modulus from small vols.; artists' paints are similarly examd. Finally the two techniques are compared as complementary methods for establishing the dynamic behavior of paint films.