Modern Oil Paints – Formulations, Organic Additives and Degradation: Some Case Studies

This study examines some of the degradation phenomena exhibited by modern oil paintings and twentieth century oil paint formulations and possible correlations with the various organic additives typically introduced by manufacturers. The research takes into consideration historical and modern tube oil paints produced by different European manufacturers and selected twentieth century oil paintings which showed degradation problems such as efflorescence, softening, cracks and sensitivity towards water and polar solvents. The composition of oil paints and paintings samples was studied with XRF, SEM-EDX, ATR-FTIR and GCMS. The results showed that both artists’ oil paints and paintings samples contain a complex mixture of additives to the oil binders and pigments. The presence of aluminium and zinc stearates, added as dispersion agent gelling agents, was detected in most paint formulations of HKS, W&N, Talens and Maimeri (c. 1940-present). Several paint films showed an unusually high content of fatty diacids, suggesting that, in drying, an oxidative reaction was favoured above polymerisation. This occurrence, together with the diversity of lipidic media, additives, pigments and driers present in the industrial formulations could play a crucial role in paint failure and instability, as showed by the analysed case studies. The obtained results may help understanding the behaviour of modern oil paints and painting surfaces and contribute to improved conservation methods.