This week’s blog post is a nice mix of science and art, which are two of my favorite subject areas.  An exciting discovery by a team of researchers at the Australian Synchrotron led to the recovery of an underlying portrait hidden upside down below Edgar Degas’s painting, “Portrait of a Woman”, which hangs in the National Gallery of Victoria in Australia.

Since the 1920s, the oil paints in Degas’s portrait of the anonymous woman in “Portrait of a Woman” (c. 1876-1880) have been gradually fading over time, revealing a possible hidden portrait underneath.

Up until now, previous attempts to capture the underlying image hidden in “Portrait of a Woman” using conventional X-ray and infrared techniques have only showed a shadowy outline of another woman.

To achieve a high-resolution image of the underlying portrait, the researchers used a synchrotron, which is a type of particle accelerator.  As sources of extremely high-energy light, synchrotrons work by directing such light (a million times brighter than the sun) into an X-ray beam (one tenth the diameter of a human hair).  At the Australian Synchrotron, the researchers used this intense X-ray beam to scan Degas’s painting via a method known as “X-ray fluorescence” (“XRF”).  Using this method, the painting is analyzed literally point by point by a unique detector in order to identify the chemical signatures of the various paint elements on a fine scale.

The team of researchers viewed an elemental map of the underlying hidden portrait as it emerged on a computer monitor over a 30-hour period.  The hidden portrait is believed to be of model Emma Dobigny, who Degas had a special fondness for as suggested by old letters from Degas.

The researchers’ work was not over just yet.  Following the synchrotron scan, the researchers had months of data interpretation ahead having been left with a terabyte of X-ray data and a black-and-white map of the underlying portrait. During this time, the researchers wrote software so that different metal elements known to be present in different paint colors could be converted into a plausible color reconstruction of the painting.

In addition to the revealing of a lost painting, this project also provides key information about Degas’s painting techniques, which could be helpful in the identification of forgeries.  This recent project using XRF technology essentially provides an entirely new level of information about Degas’s artistic process.

In case you may be wondering, it was common practice for artists at the time to paint over old canvasses.

For images of the color reconstruction of the lost painting using XRF technology see Finding Degas’s Lost Portrait With a Particle Accelerator published by the New York Times on August 4, 2016.

For detailed information on the researchers’ work see A Hidden Portrait By Edgar Degas published on nature.com on August 4, 2016.