Philippe Walter
Chemical Analysis and Painted Colours: the Mystery of Leonardo’s Sfumato

Philippe Walter


At the end of the 15th century, Italian painters explored the new effects made possible by the use of the oil medium. They created a sense of depth and relief following the Flemish technique of glazes, which allowed the spreading of very thin and translucent layers, rich in medium and with low pigment content. A striking example is given by the realisation of the shadows in the paintings of Leonardo da Vinci: the Master used the so-called “sfumato” technique based on the use of glazes to obtain a ‘smoky’ aspect for the creation of flesh tones, with very subtle contours that seem to have no hard edges. This technique has become famous nowadays, mainly because of the perfection of the art works it has allowed to achieve.

Analytical characterisations of glazes on the paintings of Leonardo and his followers allow us to improve our knowledge about this technique. As sampling of so high valuable painting areas is impossible, then an experimental non invasive approach is required. X-Ray fluorescence measurements were realised on seven paintings of Leonardo da Vinci preserved in the Louvre’s museum. This technique is widely used for qualitative determination of the pigments but it is very difficult to interpret the data quantitatively in the case of layered structures such as easel paintings.

Philippe Walter
In order to access to the composition and thickness of each layer of the carnations, we have developed a new procedure, based on the use of differential X-ray attenuation and fluorescence. Beyond the characterisation of the palette, we obtained in depth information on how Leonardo modelled his shadows. Comparisons between the different paintings of Leonardo, and also with contemporaries’ works of art, permit to highlight specific features in the Leonardo technique.

Philippe Walter - Short Biography#

Dr. Philippe Walter is research director at the Center for research and restoration of the museums of France (C2RMF-CNRS), located in the Louvre museum in Paris. He is developing new analytical tools adapted to the study of ancient materials, with the ion bean analysis facility AGLAE in his laboratory, but also with synchrotron radiation and home-made portable instruments using X-rays. His main research interests are focused on the use of analytical chemistry to understand the development of chemistry for health and beauty during Antiquity or the elaboration of new painting materials, for instance during the Renaissance period. He received a MS degree in physics at the Ecole Normale supérieure de Lyon and a PhD degree in geochemistry from Paul Sabatier University, Toulouse, France in 1993. He organized exhibitions in Cairo (2002) and Paris (2008) to show to the general public the applications of his works for the understanding of the history of body care and cosmetics. He belongs to the CNRS since 1995 and he has received in 2008 the silver medal of this French research organization.

Philippe Walter
Centre de recherche et de restauration des musées de France
Palais du Louvre
Paris, France

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