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Paris, 15 July 2010
Leonardo Da Vinci's paintings fascinate, partly due to a range of subtle optical effects that blur outlines, soften transitions and blend shadows like smoke. Known as “sfumato”, this technique is not only the result of the genius of the artist but also of technical innovations at the beginning of the 16th century. Minute observations, optical measurements and reconstitutions have already described the sfumato, but new analysis can confirm the procedure of this technique, especially related to how the gradation is done.
For the first time, Philippe Walter (LC2RMF) and his team, in collaboration with the ESRF and the Louvre Museum, have brought new insight on the sfumato thanks to a quantitative chemical study of the different painted layers. Seven paintings of Leonardo Da Vinci have been analysed without extraction, directly in the rooms of the Louvre Museum (Virgin of the Rocks, Mona Lisa, Saint John the Baptist, Annunciation, Bacchus, Belle Ferronnière, Saint Anne, the Virgin and the Child). The scientists concentrated on the study of the faces because they have the characteristics of the sfumato. They used a technique called
X-ray fluorescence(2) to determine the composition and thickness of each layer in nine faces (including Mona Lisa's) painted by Da Vinci throughout 40 years of career.
The scientists have also found different recipes used by Da Vinci to do the shadows on the faces. These recipes are characterized by a technique (the use of glaze layers or a very thin paint) and by the nature of the pigments or additives. In the case of the glazes, thin layers of 1 to 2 micrometres were applied to obtain a total thickness of no more than 30 to 40 micrometres. The results obtained in this study help to understand Da Vinci's search towards making his art look alive.

© V.A. Solé/ESRF
Photo taken during the measurements on the Mona Lisa: X-ray fluorescence spectrometry was done directly on the paintings in the Louvre Museum.

© © C2RMF
Representation of the superposition of layers in paintings in the face of Mona Lisa, on one light zone near the nose and the darker shadow of the hair. After treating the data, the thickness and concentration of pigments in the different layers.
Philippe Walter, CNRS senior researcher, the LC2RMF director and co-author of this publication, was awarded the Franco-American Franklin-Lavoisier prize 2010 on 10 May, for his advances in the study, restoration and preservation of ancient artwork thanks, notably, to the use of state-of-the-art analytical techniques.
For more information :
http://www.maisondelachimie.asso.fr/les-prix-de-la-fondation/PRIXFRANKLINLAVOISIER/le-prix-2010/view
Download high resolution images here (please, do not forget copyrights).
(1) A glaze is a fine, translucid layer, mainly organic, which contains a little bit of pigment. The superposition of glazes allows the creation of depth and volume.
(2) X-ray fluorescence spectroscopy is a chemical analytical method. It consists of making lighter an area in a painting using X-rays. Later, the material emits other X-rays (fluorescence), which are characteristic of the studied area.
Revealing the sfumato technique of Leonardo da Vinci by X-ray Fluorescence Spectroscopy
Laurence de Viguerie, Philippe Walter, Eric Laval, Bruno Mottin, V. Armando Solé
Angewandte Chemie International Edition, 2010, 49.
CNRS researcher l Philippe Walter l T 01 40 20 59 89 l philippe.walter@culture.gouv.fr
CNRS press officer l Elsa Champion l T 01 44 96 43 90 l elsa.champion@cnrs-dir.fr
Communication C2RMF l Sophie Lefèvre l T 01 40 20 56 65 l sophie.lefevre@culture.fr
Communication ESRF l Montserrat Capellas l T 04 76 88 86 63 l capellas@esrf.fr
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