A team of physicists from the Joint Institute for Nuclear Research investigated a striking color shift in a fresco at the Smolensk Cathedral of the Novodevichy Convent in Moscow. In one scene, the white folds on the archangel’s garments gradually darkened to black, a phenomenon the researchers traced to the pigment chemistry rather than a mere artistic choice. The findings were discussed with media after the team conducted their analyses.
The cathedral’s drum features archangels wearing robes in yellow, green, and red. In the oldest portions, the first two robes are drawn in white, while the red garment presents with blackened folds. Examining the base materials, the scientists found a high concentration of lead within the darker strips. Lead white, or lead carbonate, had been used to create the pale areas. Over time, this compound is susceptible to environmental stressors such as temperature shifts, humidity, and microbial activity. In many cases, it oxidizes into a nearly black form of lead oxide, a transformation documented by Olga Filippova of the Neutron Activation Analysis Group at the JINR Neutron Physics Laboratory.
Filippova notes that blackened examples exist in other Russian sites, as well as in Georgia and parts of Europe. The study shows that the darkened folds on the red robe arise from altered white lead, while the white portions of garments of other colors were painted with a lime-based white that remained stable. These observations help reconstruct what the fresco most likely looked like before the color changes occurred.
The team reconstructed the fresco fragment to demonstrate that the clothes of all colors were originally depicted with the same stylistic approach. This reconstruction clarifies the artist’s original intent and helps explain why the later conservation state differs from the initial design.
To carry out their work, researchers relied on non-destructive methods. They used a portable X-ray fluorescence analyzer to assess the elemental makeup of the painted surface on site. This technique offers rapid, in situ insight into which pigments were used most frequently without taking samples. When the color or layer cannot be determined non-invasively, scientists turn to neutron activation analysis. In this method, a sample is exposed to a flux of neutrons, triggering nuclear reactions that produce characteristic emissions. Spectrometric equipment then identifies the resulting elements and estimates the basic composition of pigments and plasters.
Through these combined methods, the scientists have progressed toward a clearer understanding of how the frescoes in the Cathedral of the Novodevichy Convent were originally colored and how environmental factors have altered those colors over time. The results underscore the importance of applying non-destructive analytical techniques to cultural heritage, enabling researchers to uncover authentic materials and historical techniques without disturbing the artifacts.
Beyond Moscow, experts have applied similar approaches to other monuments, revealing paint recipes and materials that varied across regions and periods. The Moscow study adds to a growing body of evidence showing that light, heat, humidity, and microbial activity can drive pigment changes in ancient wall paintings. By documenting these processes, researchers can inform more accurate restoration strategies and safer conservation practices for treasured frescoes around the world.
In the end, the work at the Smolensk Cathedral offers a vivid reminder that what the eye sees on a historic wall may be the product of a long, evolving chemical story. The team’s work helps place those stories into a scientific framework that enables more faithful preservation for future generations. study