Conclusion

X-ray fluorescence, a non-destructive technique that can be carried out in situ, is an invaluable tool for analyzing paintings, both qualitatively and quantitatively, thanks to the use of PyMca processing software. By taking into account the attenuation of X-rays by absorption, it is possible to calculate the composition and/or thickness of layers based on a model of the work's stratigraphy. The modelling proposed remains a hypothesis, but gives real indications of the nature of the layers, pigment concentrations and the thickness of varnishes and glazes.

Used on seven of Leonardo da Vinci's works in the Louvre, it has enabled us to better understand how the shadow effects of sfumato are achieved. The presence of glazes, which increase in thickness in shadowed areas, and the reduction in thickness of the underlying layers (mostly containing lead white) were highlighted...