From traditional to technical: using laser Doppler vibrometry to preserve frescoes

Fresco is an ancient technique in which dry pigments are applied to wet plaster to create stunning works of art that can be preserved for centuries. However, over time, these masterpieces often face deterioration due to delamination, where the decorative plaster layer peels away from the underlying masonry or structural plaster. This deterioration can compromise the structural integrity of the artwork, requiring restoration work.

Historically, conservators have gently tapped the plaster with their knuckles or a small mallet to assess the condition of a fresco. By listening to the sounds emitted, they were able to pinpoint the areas of delamination that needed repair. Although effective, this technique is limited both by the conservator’s experience and by the small number of people around the world who have these skills.

Recent research by Joseph Vignola of the Catholic University of America is revolutionizing the appreciation of frescoes. Vignola and his team applied laser Doppler vibrometry to identify delaminations in the Constantino Brumidi frescoes in the U.S. Capitol. This innovative method uses a laser to measure vibrations on the surface, allowing the team to detect areas of delamination based on their unique vibrational characteristics.

“By transmitting sound waves to induce movement in the plaster, the system captures the traces of vibrations and reveals detailed information about the structural state of the artwork,” said researcher Nicolas Ganemi. .

One of the remarkable aspects of this technique is that it can identify areas of delamination without outwardly obvious signs of damage. The group’s current research focuses on developing techniques to precisely resolve the size and shape of these hidden defects and facilitate precise restorations to ensure the preservation of works of art for future generations. are.

Additionally, advances in signal processing have enhanced the ability to analyze the complex geometry of delamination regions.

Ganemi presented research related to this research today as part of the Acoustical Society of America’s 187th Virtual Conference, November 18-22, 2024.

In this study, we examine simulations of frescoes with known delamination geometries to validate our method and ensure that artworks can be accurately assessed and repaired. These fresco surrogates also provided a platform for Vignola and his team to scientifically test the antiquated technique of knocking on frescoes and listening to their sounds.

Looking to the future, this research aims to democratize conservation expertise by creating a simple and accessible tool. One possibility is to develop a smartphone or computer application using simple algorithms that would allow anyone, regardless of their background, to participate in the preservation of the frescoes. This initiative not only strengthens the conservation process but also raises awareness of the challenges and techniques involved in maintaining these cultural treasures.

As technology continues to bridge the gap between traditional methods and modern science, fresco conservation is poised for a transformative future.

“We are developing technologies that will allow works of art to be preserved for future generations,” say the researchers.