curing process autoxidationCongratulations to our Ph.D. student Silvia Pizzimenti for her publication "Oxidation and Cross-Linking in the Curing of Air-Drying Artists’ Oil Paints" on ACS Applied Polymer Materials. The objective of this study is to improve the molecular understating of the processes that lead to the conversion of the fluid binder into a dry film, and how this evolves with time, which is at the base of a better comprehension of degradation phenomena of oil paintings, and relevant to the artists' paint manufacturing industry.

When in a painting layer, an oil - both drying and semi-drying oil, is mixed with lead white, the oil mobile phase converts quickly in a well cross-linked network and presents a relatively low degree of oxidation. Painting layers containing synthetic ultramarine blue present a very different behaviour, especially when a semi-drying oil is used. On the whole, it is clear that increased levels of oxidative degradation occur in synthetic ultramarine blue paintings in comparison to lead white ones, and significantly more when ultramarine blue is used in combination with safflower oil. As a result, it can be expected that an ultramarine blue painting layer is less cross-linked than a lead white based one, when other factors (oil type, additives, age, conservation conditions, etc) are the same. This tendency of ultramarine blue to favour oxidative degradation over cross-linking may be related to documented conservation issues of ultramarine paining layers, from the loss of cohesion to the establishment of water sensitivity.
The work is available at the following link: