Why synthetic emerald-green pigments degrade over time
The advent of synthetic pigments in the 19th century revolutionized the art world, providing artists like Paul Cézanne, Vincent van Gogh, Edvard Munch, and Claude Monet with vibrant colors that transformed their work. Among these, emerald-green pigments stood out for their intense brilliance, allowing for a new depth of expression in paintings. However, the allure of these synthetic hues came with a significant downside: many of these pigments were prone to degradation over time. This deterioration often manifested as cracks, uneven surfaces, and the formation of dark copper oxides, and in some cases, the release of toxic arsenic compounds. Such issues have raised major concerns among art conservators tasked with preserving these masterpieces for future generations.
In a promising development for art conservation, European researchers have employed synchrotron radiation and other advanced analytical techniques to investigate the underlying causes of pigment degradation. Their findings, published in the journal *Science Advances*, aim to determine whether factors like light exposure and humidity are responsible for the deterioration of these vibrant colors. This research is part of a broader trend where scientific advancements are increasingly utilized in the field of art conservation. For example, a study conducted in 2019 revealed that many oil paintings at the Georgia O’Keeffe Museum were developing tiny, pin-sized blisters, which were later identified as metal carboxylate soaps—a byproduct of chemical reactions between metal ions in the pigments and fatty acids in the binding medium. Such insights not only enhance our understanding of the materials used by artists but also inform better conservation practices to protect these invaluable works of art.
As researchers continue to explore the interactions between light, humidity, and synthetic pigments, the hope is that they will uncover more effective strategies for preserving the integrity of iconic artworks. This intersection of art and science underscores the importance of interdisciplinary approaches in tackling the challenges faced by art conservators today. By leveraging cutting-edge technology and scientific analysis, we can ensure that the brilliance of the past remains vivid and accessible for future audiences.
The emergence of synthetic pigments in the 19th century had an immense impact on the art world, particularly the availability of emerald-green pigments, prized for their intense brilliance by such masters as Paul Cézanne, Edvard Munch, Vincent van Gogh, and Claude Monet. The downside was that these pigments often degraded over time, resulting in cracks and uneven surfaces and the formation of dark copper oxides—even the release of arsenic compounds.
Naturally, it’s a major concern for conservationists of such masterpieces. So it should be welcome news that European researchers have used synchrotron radiation and various other analytical tools to determine whether light and/or humidity are the culprits behind that degradation and how, specifically, it occurs, according to
a paper
published in the journal Science Advances.
Science has become a valuable tool for art conservationists, especially various X-ray imaging methods. For instance, in 2019,
we reported
on how many of the oil paintings at the Georgia O’Keeffe Museum in Santa Fe, New Mexico, had been developing tiny, pin-sized blisters, almost like acne, for decades. Chemists concluded that the blisters are actually metal carboxylate soaps, the result of a chemical reaction between metal ions in the lead and zinc pigments and fatty acids in the binding medium used in the paint. The soaps start to clump together to form the blisters and migrate through the paint film.
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