Year of selection 2017
Institution The National Gallery - Scientific Department, London
Country United Kingdom
The darkening yellow of Vincent Van Gogh’s sunflowers and the paling of Vermeer’s signature ultramarine blue are famous examples of how paintings suffer changes over time. Such degradation or alteration processes can dramatically affect their appreciation and interpretation. To set up efficient and tailored conservation strategies, museums need in-depth knowledge of the painting’s constituent materials (pigments, paint medium, varnishes…) and distribution. Cutting edge imaging technologies offer promising opportunities for conducting such investigations. Unlike the more commonly used analytical methods that require sampling, imaging techniques are non-invasive and can provide a broader overview. « While the analysis of samples provides detailed valuable information on a specific point in a painting, this may not be representative of the condition of the painting as a whole », Dr. Marta Melchiorre Di Crescendo of the National Gallery in London points out. This is why her project aims to assess the potential of two promising and complementary cutting edge non-invasive analytical techniques that have not yet been extensively used in conservation applications: hyperspectral imaging reflectance spectroscopy (HSI) and macro X-ray fluorescence scanning (MA-XRF).
« MA-XRF uses X-rays to investigate the elemental composition of materials associated with a painting. The data can be processed to produce a series of separate maps showing the spatial distribution of different elements which can be related to the distribution of different materials », explains Dr. Marta Melchiorre Di Crescendo. « HSI uses visible and infrared radiation to characterise a range of features and materials associated with a painting at very high spectral and spatial resolution. It can be used to identify and map the distribution of different materials across the surface of the painting and, to a certain extent, within the paint layer structure ». « The combined use of these systems is expected to allow the identification of materials associated with paintings and degradation phenomena, precisely visualising their distribution across the painting surface, while avoiding or minimising the intrinsic risks associated with taking micro-samples », the conservation scientist resumes.
Where art meets science
The objective of the project is two-fold: to determine to what extent MA-XRF and HSI can help understand the propensity of some painting materials (pigments and binders) to undergo deterioration processes resulting in colour change, and assess their potential as flexible tools to assess the condition of the paintings and inform conservation practice. To meet these goals, the project will include two consecutive stages, the first to establish optimised MA-XRF and HSI protocols and the second to put these methods into practice. « We will start with an initial phase during which both imaging techniques will be tested on reference materials, paint reconstructions and a limited selection of the London Gallery’s paintings. The comparison of results from the same reference materials and paintings gathered with both the novel non-invasive analytical techniques and more traditional analytical techniques will guide the optimization of MA-XRF and HSI protocols for the visualization and identification of different phenomena and materials », Dr. Marta Melchiorre Di Crescendo specifies. « It is only then that the optimized MA-XRF and HSI protocols will be used to investigate a larger number of the National Gallery’s paintings, disclosing new information on the condition of the paintings and on the degradation of a selected range of painting materials ».
Science and art have an enduring relationship and a lot in common. For one thing, both can help inform each other. Projects like Dr. Marta Melchiorre Di Crescendo’s, which use state-of-the-art science to investigate art, will play an essential part in ensuring the sustainability of our cultural heritage.The outcome of her research will indeed provide new and unique insights into both the paintings’ future and past, paving the way for tailored conservation strategies, as well as for informed interpretation.