24 OCT 2018

When the Laboratory of Molecular and Structural Archeology (LAMS) is invited into a museum, it can only be described as “chemistry meets creativity". Created in 2012, this laboratory led by Philippe Walter pursues research in the chemistry of heritage materials with two objectives: to study the evolution of materials used in artistic creation and to analyze the synthesis of ancient components.  to inform the research and development of today.

instrument de diffraction X
Nicolas Poussin's painting with the diffraction instrument X (Rouen Museum) © LAMS
  • A chemistry laboratory at the service of art

Whether they are prehistoric caves, Egyptian antiquity, or easel painting, the LAMS teams seek to decipher the processes of artistic creation. Chemists, Egyptologists, philologists, archaeologists, art historians and art restorers work together to uncover the secrets of artist studios.

They conduct a broad study including the origin of pigments, the selection of materials, their mixture, the way in which colors and light are represented. There are many clues to understanding the evolution of artistic techniques.
"The interdisciplinary and complementary skills of the laboratory enables us to advance our knowledge of the material history of these works of art," says Philippe Walter.

  • Advanced methods developed in a mobile laboratory

Philippe Walter and his team have developed a highly sophisticated mobile laboratory to get closer to works in museums and archaeological sites. With the help of measuring instruments that fit in a small suitcase and weigh only a few pounds, these art archaeologists delve deeply into the layers of paint. Far from the simple radiography used at the beginning of the 20th century, these new methods of spectrometry* allow scientists to obtain a lot of information in a short time.

"Fluorescence spectrometry can identify chemical elements while X-ray diffraction makes it possible to recognize minerals. With nuclear magnetic resonance, we get information about binders and some pigments. Finally, thanks to hyperspectral imagery, we are able to use infrared to reveal what is under the visible layers, "explains Philippe Walter.

The combination of these different portable and non-invasive devices makes it possible to obtain the detailed composition of the materials used in the works.

  • Build a history of art from the materials used

The goal is not only to describe the palette of pigments used in a work, but also to build a true history of art materials. To do this, scientists spend several years studying painting by painting and artist by artist to develop hypotheses on the aesthetic choices of painters and the evolution of their practices.

"We are studying very specific aspects. We look, for example, at the color of the shadows on a garment in the paintings of Nicolas Poussin, "says Philippe Walter.

Thanks to measurements made on light or dark areas in the painting, the researchers showed that, unlike his predecessors, Nicolas Poussin did not use the same pigment to represent an identical color in the shadow as in the light.

"Before him, Raphael or Leonardo da Vinci added a black glaze on a uniform color to create the shadow zone. Nicolas Poussin had, thanks to advances in the field of optics and understanding the functioning of vision, understood the distinction between a pigment and its apparent color as we perceive it, "says Philippe Walter.

  • Various collaborations around the world

To study these works, the laboratory has set up numerous collaborations with museums, for example, the Capodimonte National Museum in Naples or the Barberini Palace in Rome. The lab also works on archaeological sites such as the tombs for the time of Ramses II in Luxor.

LAMS also collaborates with other structures. It founded the Lab4art with the Atelier du Temps Passé** that specializes in the conservation and restoration of works of art. Lab4art is a structure that combines the scientific expertise of the laboratory and the know-how of the workshop to develop innovative, non-invasive methods and provide data useful for the authentication of works of art. 

* Spectrometry is the study of how light interacts with matter and determines its chemical composition. There are several types of spectrometry that are complementary in the analysis of matter (X-ray fluorescence spectrometry, visible and near-infrared hyperspectral imaging, and nuclear magnetic resonance spectrometry).
** “The Studio from a Former Time”