Researchers Uncover Causes of Synthetic Emerald-Green Pigment Degradation

The degradation of synthetic emerald-green pigments has been a significant concern for art conservators. Recent research published in the journal Science Advances reveals that light and humidity are key factors in this deterioration process. Led by scientists from the University of Perugia, the study provides insights into the degradation mechanisms affecting these vibrant pigments, which were highly sought after by renowned artists like Paul Cézanne, Vincent van Gogh, and Claude Monet.

The study stems from the long-standing issue that while synthetic pigments revolutionized art in the 19th century, they often lead to cracks, uneven surfaces, and the formation of harmful compounds such as copper oxides and arsenic. The research team aimed to clarify how environmental factors contribute to these problems.

Methodology and Findings

To investigate the degradation of emerald-green pigments, the researchers collected microsamples from James Ensor’s painting, The Intrigue (1890), currently held at the Royal Museum of Fine Arts in Antwerp. Using advanced techniques such as Fourier transform infrared imaging and synchrotron radiation X-ray analysis, they examined both historical and commercial samples of the pigment.

The team created mockups by mixing commercial emerald-green powders with linseed oil and subjected these samples to aging tests. They discovered that humidity leads to the formation of arsenolite, which makes the paint brittle and susceptible to flaking. Conversely, exposure to light causes the pigment’s trivalent arsenic to oxidize into pentavalent compounds, resulting in a dull appearance and a white layer forming on the surface.

These findings align with previous research on other artworks, including a 2020 study on Edvard Munch’s The Scream, which revealed that humidity had a more significant impact on deterioration than light exposure.

Broader Implications for Art Conservation

The implications of this research extend beyond emerald-green pigments. For years, art conservators have grappled with the challenges posed by synthetic materials. The study underscores the importance of understanding the specific conditions that can lead to degradation, enabling more effective conservation strategies.

The Metropolitan Museum of Art in New York City is currently investigating similar deterioration issues in traditional oil paintings. Their ongoing project aims to determine the causes and mechanisms behind metal soap formations, which have been observed across various historical artworks.

As art conservators continue to adopt scientific methods to address these challenges, insights from this latest study could help preserve masterpieces for future generations. The findings emphasize the need for careful environmental control in museums and galleries, particularly to mitigate the effects of humidity and light on sensitive artworks.

With the art world increasingly reliant on scientific analysis, research like this plays a critical role in safeguarding cultural heritage. The discovery that light is a primary threat to emerald-green pigments not only enhances our understanding of art materials but also paves the way for improved conservation practices in the years to come.