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Science meets historic art: forensic biochemistry uses modern techniques to reveal artist's painting methods

18 August 2022

If you were to gaze upon the relief depicting the ‘Virgin and Child with saints and angels’ by Renaissance master Donatello, you would be forgiven for not considering how fish bones, milk and egg yolk were instrumental in the masterpiece’s creation. Yet this is what has been discovered using novel analysis techniques, thanks to a joint project between Dr Nunzianda Frascione (Forensic Biochemistry research group, King's Forensics) and Dr Lucia Brugio (Science Division, Victoria & Albert Museum).

Cast in stucco and then painted, the oval relief is thought to have been created by renowned-sculptor Donatello at a workshop in Florence between 1430 and 1440. Due to its fragile nature, it has proven a challenge for those wishing to accurately analyse the painting’s chemical composition without damaging it. The collaboration between the Victoria & Albert Museum (V&A) and King’s has meant that - for the first time - the chemical make-up of the relief has been successfully profiled.

Conducted by PhD student Alvaro Varela Morillas and MSc student Ria Chittaranjan Sarkar, the project explored a multi-analytical approach. This combined several sensitive and non-destructive techniques, including scanning electron microscopy with energy dispersive X-ray analysis and Raman microscopy. The analysis, which examined minute samples of the painting, provided insight into the painting process, the various stages, and the palettes used by Donatello.

The Desorption Electrospray Ionisation Mass Spectrometry Imaging (DESI-MSI) machine

In addition, the study explored the use of Desorption Electrospray Ionisation Mass Spectrometry Imaging (DESI-MSI) – a novel technique never used before in the analysis of paintworks. This technique was able to detect molecules in trace amounts, which is essential in the analysis of minute samples. In contrast to other techniques, it operates at atmospheric pressure, meaning that it can be used on solid samples with little to no sample preparation. This, in turn, is of great value when analysing delicate subjects such as artwork.

With the Donatello relief, DESI-MSI showed great analytical value by displaying the characterisation of varnishes and other binding components made from natural products such as milk, fish bones or egg yolk. It also detected biomarkers that provide evidence of the presence of drying oils, such as linseed, walnut or poppyseed oil, as well as natural waxes such as beeswax. These materials, which were commonly used in the 15^th century, would have been used as binding agents to bond the paint pigment, allowing them to remain on the coated surface when dry.

Overall, this collaboration has proved the capability of the described techniques to accurately profile the different components present in highly valuable artworks without causing material damage to them. They provide essential information to both understand the history and relevance of any plastic artwork.– Dr Nunzianda Frascione, Senior Lecturer in Forensic Science, King's Forensics

The successful implementation of the new technique on the relief could also have significant implications in combating the ongoing issue of art forgery – a crime with serious impacts in the global community.

This provides an additional dimension of information by reporting a chemical profile of the organic components present in a piece of artwork. An art historian can then determine whether the presence of these components is concurrent with the period when said artwork was allegedly produced or not.– Alvaro Varela Morillas, PhD student

The next time you find yourself admiring a piece of Renaissance art at an exhibition, think not only of its beauty. Also consider how it might have been made and the use of materials we could only have confirmed using scientific techniques.