Ultramarine Blue in Edvard Munch’s Collection: A Multi-Analytical Study of Early 20th Century Commercial Oil Paints

The recurrence of specific deteriorating phenomena in blue paints used by Edvard Munch, observed more frequently from artworks from 1907 and onwards, calls for an analytical investigation of these paints. Ten commercial Ultramarine blue oil paint tubes from Munch’s studio materials were studied, employing a multi-analytical approach comprising ATR-FTIR, µ-Raman, GC-MS, and SEM-EDS techniques. This study aims to ascertain the composition of these industrially produced blue oil paints and shed more light on the potential implications for darkening and other deterioration phenomena observed in Munch’s artworks. The analyzed samples exhibited complex mixtures, characterized by significant presences of additives such as non-drying or partially drying oils, metal soaps, and preservatives. Moreover, extenders including clay minerals and white and other blue pigments were identified. Some compositions diverged from those indicated on the labels of the tubes. This study presents hypotheses regarding the causes of deterioration mechanisms observed in Ultramarine blue paints and outlines future perspectives and implications of darkening and other surface degradation phenomena in paintings from MUNCH’s collection towards best conservation and display practices.