Novel mass spectrometric approaches for the analysis of modern oil paint media and organic additives in paintings

Modern unvarnished oil paints in paintings show degradation problems such as bleeding, efflorescence and solvent sensitivity1 which are related to specific lipidic media and additives in the paint. Micro-analytical techniques such as Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography/Mass spectrometry (GCMS) are routinely used for detection of organic materials in oil paints. The type of oil may be determined based on characteristic peak ratios of mainly palmitic and stearic acid, using GCMS. However, the techniques are less specific if other lipidic components are present. Moreover, using standard preparation techniques GCMS provides only limited information about important parameters which reflect the original composition and the state of ageing or degradation through oxidation, hydrolysis and soap formation. In general, a combination of analytical techniques and/or extensive sample pretreatment is required to obtain such information.2,3 This paper discusses 20th C oil paint technology and the organic components that may be present in fresh and dried oil paints. An overview is given of novel mass spectrometric techniques which can be used for detection of these original materials and their drying and degradation products, and compared to GCMS techniques which involve pretreatment and derivatisation procedures.