Paint choice found to be a preservation problem in art conservation.
This article demonstrates an application of science in a field often missed by students when considering STEM careers. This resource could be used alongside STEM Pack 6: Art Conservation with students in years 8, 9, and 10 studying Chemical and Physical sciences.
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Some heavy-duty science has been employed to try to better understand and preserve one of the world’s best-known works of art – Edvard Munch’s The Scream.
An international team led by Italy’s CNR has used non-invasive spectroscopic methods and synchrotron X-ray techniques to study in detail the nature of the various pigments Munch used, and how these have degraded over the years.
Collaborators from Italy, Germany, Belgium the US and France first brought the European mobile platform MOLAB to the Munch Museum in Oslo, Norway, then moved to Grenoble, France, and the European Synchrotron, the world’s brightest X-ray source.
“The synchrotron micro-analyses allowed us to pinpoint the main reason that made the painting decline, which is moisture,” says CNR’s Letizia Monico, one of the corresponding authors of a paper in the journal Science Advances. “We also found that the impact of light in the paint is minor.”
There are, in fact, a number of versions of The Scream: two paintings, two pastels, several lithographic prints and a few drawings and sketches. The most well-known are the paintings, created in 1893 and circa 1910 – the latter held by the Munch Museum.
Each is unique, and that is part of the problem, the researchers say. Munch experimented to find the exact colours to represent his personal experience, mixing diverse binding media (tempera, oil and pastel) with synthetic pigments to make “screaming colours”.
Unfortunately, the extensive use of these new coloured materials poses a challenge for the long-term preservation of the 1910 painting, which clearly shows signs of degradation in different areas where cadmium-sulfide-based pigments have been used.
The painting has not always been well cared for, of course. It was stolen in 2004 and missing for two years.
Since its recovery, it has rarely been shown to the public. Instead, it is preserved in a protected storage area in the Munch Museum under controlled conditions of lighting, temperature (about 18 degrees Celsius) and relative humidity (about 50%).
The study shows that the original cadmium sulfide turns into cadmium sulfate in the presence of chloride-compounds in high-moisture conditions. This happens even if there is no light.
“The right formula to preserve and display the main version of The Scream on a permanent basis should include the mitigation of the degradation of the cadmium yellow pigment by minimising the exposure of the painting to excessively high moisture levels – trying to reach 45% RH or lower – while keeping the lighting at standard values foreseen for lightfast painting materials,” says Irina Sandu, the museum’s conservation scientist.
“The results of this study provide new knowledge, which may lead to practical adjustments to the Museum’s conservation strategy.”
Munch wasn’t alone in using cadmium-sulfide-based yellows. They are present in the work of such noted contemporaries as Henri Matisse, Vincent van Gogh and James Ensor.
“The integration of non-invasive in-situ investigations at the macro-scale level with synchrotron micro-analyses proved its worth in helping us to understand complex alteration processes.,” says MOLAB’s Costanza Miliani.
“It can be profitably exploited for interrogating masterpieces that could suffer from the same weakness.”
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