X-rays shed light on mystery behind da Vinci’s stroke of genius

The secret of how Leonardo da Vinci captured Mona Lisa’s enigmatic smile can be revealed.

Scientists have discovered how the artist managed to achieve his trademark smoky effect, known as sfumato, on the painting - by applying up to 40 layers of extremely thin glaze thought to have been smeared on with his fingers.

The glaze, mixed with subtly different pigments, creates the slight blurring and shadows around the mouth that give Mona Lisa her barely noticeable smile that seems to disappear when looked at directly.

Using X-rays to study the painting, the researchers were able to see how the layers of glaze and paint had been built up to varying levels on different areas of the face. With the drying times for the glaze taking months, such effects would have taken years to achieve.

The scientists also suspect that he used his fingers to apply the glaze as there are no visible brush marks or contours.

Da Vinci is known to have employed the sfumato effect to seamlessly blend shading and blur outlines, but the exact techniques used have long intrigued art experts.

The discoveries have been made by scientists at Laboratoire du Centre de Recherche et de Restauration des Musees de France and the European Synchrotron Radiation Facility.

Dr Philippe Walter, who led the study, said: “The perfection of Leonardo da Vinci’s painting technique has always been fascinating.

“The gradation of tones or colours from light to dark is barely perceptible … The thinness of the glaze layers must be underlined: it confirms the dexterity of the painter to apply such thin layers.

“Moreover, the measured slow and regular evolution of the thickness of the glaze layers implies that numerous layers have to be applied to obtain the darkest shadows. Even today, Leonardo’s realisation of such thin layers remains an amazing feat.”

The scientists used a technique known as X-ray fluorescence spectroscopy to study the painting as it allowed them to examine the layers of glaze and paint without having to take samples that would damage the masterpiece.

A beam of high-energy X-rays was focused on the painting, which allowed the researchers to determine how the layers of glaze and paint were built up while also giving them information about their composition.

As well as the Mona Lisa, the team studied six other da Vinci paintings, including The Virgin of the Rocks, The Madonna of the Carnation, Saint John the Baptist and The Virgin and Child with Saint Anne.

Professor Francis Ames-Lewis, of the Leonardo da Vinci Society, said: “Leonardo da Vinci was concerned with producing smooth tonal gradients from light to dark without any perceptible change, like we see in real life - and sfumato was essential to this.” - (The Telegraph)