Under beams of X-rays, the colours of art become the colours of chemistry. The mysterious blacks, reds and whites of ancient Greek pottery can be read in elements – iron, potassium , calcium and zinc – and art history may be rewritten.
Image on Greek vase.( Image) https://2.bp.blogspot,com
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Stanford’s Cantor Arts Center worked with SLAC scientists to explore the chemistry hidden under the paintings on this Greek flask.The chemical map image shows calcium(green) matching the white areas in the driver’s tunic and dot accents, and iron (red) and potassium (blue) matching the black of the horse and figure silhouettes. (Credit : SLAC National Accelerator Laboratory)
That’s the power of a growing collaboration between the Cantor Arts Center’s Art and Science Learning Lab, art and science faculty, and the Stanford Synchrotron Radiation Light source (SSRL) at SLAC National Accelerator Laboratory.
Having a faculty like SSRL just up the hill from the Cantor’s conservation lab lends a unique opportunity for students to probe cultural mysteries with advanced scientific tools, say Susan Roberts- Manganelli,director of the Learning Lab. About two years ago she started a fellowship for science students interested in studying art conservation. She works closely with SSRL scientific staff to mentor students bringing delicate, valuable art objects to SLAC in search of discoveries that benefit art and science
A chemical map of Greek art revealed that a calcium-based colour additive was used for white, which would have added an additional step .It also raised questions about the firing process due to the absence of zinc in the black regions. It had been assumed that a zinc additive was key to achieving the black figures in the heating process.(Credit SLAC National Accelerator Laboratory)
“We can do a lot of testing here at the Cantor,” Roberts Manganelli says, “But some studies need more robust collaboration and more powerful X-rays to actually get answers to our questions.” One such study, done by Kevin Chow, BS’ 13, when he was a senior in collaboration with Stanford, SLAC and the Getty Conservation Institute, took a deeper look at the techniques of the ancient Greek potters, which are difficult to reproduce and not entirely understood. Using a technique called synchrotron X-ray fluorescence, the team was able to uncover surprising steps in the production process that challenge the conventional understanding.
Athenian oil-flask ( Lekythos) from 500-480 BC; decorated in the black-figure technique (Credit SLAC National Accelerator Laboratory)
“Under what they thought was a single coat, they found other instances of painting that the naked eye could not see,” says Chow’s advisor Jody Maxim, associate professor of art and art history and of classics. “It was thrilling to learn that a very humble vase – hundreds of these were produced for the Festival of Athena every four years – shows certain standards of aesthetic excellence. The artists invested more in his work than we had given him credit for.”
Such collaboration spark scientific innovation as well. Well conserved art objects allow researchers to look at uniquely complex materials of a certain age that generate intriguing chemistry questions and require new techniques, says SLAC staff scientist Apurva Mechta, who is also an affiliated faculty member at the Stanford Archaeology Center. ” We had to find a way to see all layers of the Greek pot in detail, which is something we want to do for other materials that might be used in batteries or electronics.”
A custom-made mount held the delicate pot during a rotational scan at SSRL
(Credit SLAC National Accelerator Laboratory)
Source: SLAC National Accelerator Laboratory)