Full title: Preliminary investigations into crystalline efflorescence on Australian and Indigenous paintings in the NGA & NGV collections g research in progresa
A substantial number of paintings in Australian public and private collections have been observed to develop a whitish deposit either directly on the surface of the painting or on the interior of glass used to glaze the painting. Crystalline efflorescence has been noted on paintings in the National Gallery of Australia (NGA) collection for over 10 years and appears to be affecting a wide variety of medium and age of art works. However the phenomenon is most severe on a group of mid 20th Century Australian paintings. The recent observation of the effect occurring in the National Gallery of Victoria (NGV) will allow for data to be collected on exact storage conditions that has not historically been kept for all the works in the NGA and at the same time provide comparisons with a longer history of crystalline growth.
Previous studies in the literature have found this material to be mobilised fractions of the binding medium, and in the case of oil or oil containing (eg: alkyd) paints these were found to be fatty acids. They are derived from oil medium’s constituent triglycerides. Palmitic and stearic acids predominate in the deposit due to their relatively low carbon chain length and unsaturation in comparison to other fatty acids, and their comparatively low melting and boiling points. Preliminary analyses of bloom deposits on paintings in the NGV and NGA have produced similar results.
This project proposes a scheme to investigate the phenomenon in a large number of paintings (approximately 100) in collections of the NGV and NGA through sequential characterisation of the surface deposits and underlying paint medium. The advantages of surveying a large number of paintings will be an ability to correlate surface deposit character with binding medium composition, and understand the significance of pigment type on the formation of deposits. The second part of the project is a study of ‘ghosting’ in order to better understand the conditions that contribute to the formation of fatty acid deposits on glass.
Previous studies have left numerous major questions unanswered. Through computational modelling, this project will additionally seek to provide insight into possible mechanisms that initiate fatty acid migration. The project will specifically examine the host paint films and external environmental influences. The experimental methodology will be to characterise pigments and binding media in affected paintings, characterise the bloom composition and include as many observational and historical notes as possible in order to examine any correlations. This will be achieved with a combination of Fourier Transform Infrared Spectroscopy (FTIR) and Direct Temperature resolved Mass Spectroscopy (DTMS), Scanning Electron Microscopy – Energy Dispersive X-Ray Spectroscopy (SEM-EDS) and additional techniques as required. Artificially aged samples of paint materials will also be prepared and analysed in order to further investigate the effect of environmental conditions (e.g.; air flow, temperature and RH) on the development of surface crystallisation and ghosting on glass.