Identification of metal soaps and other degradation products in modern oil paints

The appearance of white hazes and crusts of different morphologies is a common deterioration observed in contemporary oil paintings. The identification of these whitening phenomena is a challenge since they can be attributed to the formation of metal soaps but also to the appearance of microorganisms, salts, starch, etc. In order to identify these white hazes and crusts we are developing a systematic analytical approach that includes several techniques: optical microscopy, SEM-EDS, ATR-FTIR, Raman spectroscopy, XPS µ-XRF and XRD. We apply these techniques to cross sections, surface microsamples and/or scrapings from the whitened surfaces so that we can also better understand the mechanisms behind their formation. This will help us to develop more efficient strategies for the removal of the whitening phenomena.