The secret behind her darn smile

Scientists finally uncover Leonardo da Vinci's secret technique to creating the enigmatic Mona Lisa smile

Richard Gray

features@mediacorp.com.sg

THE secret of how Leonardo da Vinci produced the optical effects that created the Mona Lisa’s enigmatic smile can be revealed for the first time.

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 the 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 to his paintings as there are no brush marks or contours visible on the paintings.

Leonardo is known to have employed the sfumato effect to seamlessly blend shading together and to blur outlines.

But the exact techniques used to achieve this have long fascinated and intrigued art experts.

The new 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.

Writing in the scientific journal

“The gradation of tones or colours from light to dark is barely perceptible.

Above all, the way the flesh is rendered gives rise to many comments because of its crucial role in the fascination exerted by Leonardo’s portraits.

“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 still 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 in detail without having to take samples that would damage the masterpiece.

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

As well as the Mona Lisa, the team also studied skin tones in six other of Leonardo’s most famous paintings, including