Perhaps most relevant to this article is a 2020 study in which scientists analyzed Munch's book Scream, which showed alarming signs of degradation. They concluded that the damage was caused not by exposure to light, but by moisture—specifically, the breath of museum visitors, perhaps when they lean in to take a closer look at the master's brushstrokes.
Let there be (X-ray) light
Co-author Laetitia Monico during experiments at the European Synchrotron.
ESRF
Co-author Annelies Rios Casier (University of Antwerp) takes microsamples from the green area Intrigue.
Lie Vanbeervliet
Co-author Annelies Rios Casier (University of Antwerp) takes microsamples from the green area Intrigue.
Lie Vanbeervliet
Microphotographs of paint fragments taken from two altered emerald green areas Intrigueanalyzed using vibrational spectroscopy and advanced synchrotron techniques.
Miliani et al., 2025
Microphotographs of paint fragments taken from two altered emerald green areas Intrigueanalyzed using vibrational spectroscopy and advanced synchrotron techniques.
Miliani et al., 2025
Co-author Annelies Rios Casier (University of Antwerp) takes microsamples from the green area Intrigue.
Lie Vanbeervliet
Microphotographs of paint fragments taken from two altered emerald green areas Intrigueanalyzed using vibrational spectroscopy and advanced synchrotron techniques.
Miliani et al., 2025
Emerald green pigments are particularly prone to degradation, so the authors of the latest paper decided to analyze this particular pigment. “It was already known that emerald green degrades over time, but we wanted to understand exactly the role of light and humidity in this degradation,” said co-author Laetitia Monico University of Perugia in Italy.
The first step was to collect micro-samples of emerald green paint using a scalpel and stereo microscope from works of art from the period – in this case Intrigue (1890) author James Ensorcurrently housed in the Royal Museum of Fine Arts in Antwerp, Belgium. The team analyzed the raw samples using Fourier transform infrared imaging and then embedded the samples in polyester resin for synchrotron X-ray analysis. They conducted separate analyzes of both commercial and historical samples of emerald green pigment powders and paint tubes, including one from the museum's collection of paint tubes used by Munch.
The authors then created their own paint designs by mixing commercial emerald green pigment powders and their laboratory powders with linseed oil, and then applied the mixture to polycarbonate substrates. They also squeezed paint from a Munch tube onto the substrate. After the mock-ups were dry, thin samples were cut from each mock-up and also analyzed using synchrotron radiation. The mock-ups were then subjected to two aging protocols designed to determine the effects of ultraviolet light (to simulate indoor lighting) and humidity on the pigments.
Results: In the mock-ups, light and humidity cause different decomposition paths for emerald green paints. Humidity causes the formation of arsenolite, which makes the paint brittle and prone to peeling. Light dulls the color by causing the trivalent arsenic already in the pigment to oxidize to pentavalent compounds, forming a thin white layer on the surface. These results are consistent with analyzed samples taken from Intriguewhich confirms that the degradation is due to photo-oxidation. It turns out that light is the greatest threat to this particular painting and perhaps to other masterpieces from the same period.
Achievements of science, 2025. DOI: 10.1126/Sciadv.ady1807 (About DOI).
