Shwedagon Pagoda is hard to miss.
Sitting atop a hill in Yangon, the largest city in Myanmar, the pagoda’s main stupa, or dome, rises over 112 meters into the air and dominates the urban skyline.
It is also encrusted with over 7,000 diamonds, rubies, and sapphires and covered completely in gold—anywhere from 9 to 60 tons of the precious metal.
But over time, the gold leaf peels and flakes off, so the temple needs to be renovated every 4 or 5 years. In fact, a small gold mill was recently constructed within the Shwedagon compound to help produce and supply the gold needed for restoration.
This restoration process is expensive but necessary: At an estimated 2,600 years of age, the Shwedagon Pagoda is one of the world’s oldest Buddhist temples and Myanmar’s most sacred.
Now, materials scientists in Belgium are researching what exactly is causing the gold to peel—and what could be done to make the dome more durable to Myanmar’s temperature and humidity.
Last November, Herman Terryn, an engineering professor at the Free University of Brussels, was invited by the Myanmar government as a speaker for a special workshop investigating better and more durable ways to replace the gold dome. The visit has led to an ongoing collaboration, led by graduate student Lise Vermeersch, with Yangon Technological University, Shewedagon’s on-site museum, and Myanmar’s Ministry of Religious Affairs and Culture to study why the structure is failing and new methods for future renovations.
“I was very excited that someone is studying this,” said Sameh Tawfick, an assistant professor of mechanical engineering researching solid materials at the University of Illinois. “And it’s useful beyond this temple. Even in modern architecture, there are so many gilded structures.”
Weathering the Material Problems
The Shwedagon’s dome is made up of thousands of gold plates, made by gluing gold foil to a copper base. The connection between each component of the plate—the gold, glue, and copper—may be weakened by environmental conditions.
The temple is located near a sea in the monsoon region of Asia, so persistent humidity and salty rains can damage components of the dome.
“We know that saline environments can corrode copper,” said Vermeersch. And it’s possible that it affects the bond between the gold and glue. “That is something that is known, but it really depends on specific conditions, so that is something that should be tested.”
But the greatest threat may be temperature variation. “The most challenging part is how all of these conditions will change as a function of temperature cycle, whether between night and day or between seasons,” said Tawfick, who was not involved in the research.
“The fact that the temple is in the Sun [means] it will heat up quite a lot,” Vermeersch said. “The gold and copper and glue will have different expansion factors, and this will cause a difference in expansion, therefore some thermal stresses.”
Climate change thus threatens both the world’s future and its history. With more extreme weather and temperature fluctuations expected in the coming decades, the thermal stresses on Shwedagon’s golden dome will likely grow.
“When the variations become more extreme, the problem will be even larger,” Tawfick said.
Birds can be another source of initial wear and tear, as they can literally peck at the dome surface when hunting for food. “There might be a kind of mechanical impact from a bird pecking which may make some local failure of the gold,” Terryn said.
Vermeersch will first test what is in the glue that binds the gold and copper together, using a variety of techniques to analyze and visualize its physical composition at an atomic scale.
The researchers plan to then test lab-made gold plates using the same materials and glue in a climate chamber that exposes the samples to similar levels of humidity, temperature, salinity, and ultraviolet rays that the Shwedagon Pagoda is subject to. By comparing the artificially aged gold plates with the samples from the actual dome, the researchers hope to understand the mechanisms behind the deterioration.
Unplanned Pause in Research
Unfortunately, the coronavirus pandemic has disrupted the project. The researchers received samples from the dome in mid-February, but the lab was closed by 8 March, Terryn said. Communication with collaborators in Myanmar has been difficult, and a planned trip in the fall may not be able to happen.
Despite these difficulties, the research may provide novel solutions to preserving this temple and other buildings facing similar problems around the world.
“I’m very enthusiastic about this temple for the reason that you are able to visit a religious place where you [actually] see the Buddhism religion, how they do it,” Terryn said.
And by trying to preserve this unique and ancient cultural heritage, the research may uncover new innovations in materials science as a field.
“Although the problem is ancient, I think even the most advanced solutions may not work, and this research may require out-of-the-box ideas or solutions tailored for a specific problem, not an existing solution,” said Tawfick.
—Richard J. Sima (@richardsima), Science Writer