The three seated figures stare contemplatively outward, their legs folded and their torsos swathed in simple one-shoulder robes. Once resplendent in gold leaf-plated skin, the statues have degraded over the centuries, the eye-popping color of their bodies and dress giving way to earthy browns and blacks, the craftsmanship underlying them laid bare at the expense of their shine. All three works depict the Buddha, all three were sculpted more than 1,300 years ago in China, and all three feature layers of lacquer made from the sap of a single species of tree. They are the only known Buddhas of their time period to evince this technique.

This intriguing trio of statues is the subject of the exhibition “Secrets of the Lacquer Buddha,” which debuted at the Smithsonian’s Sackler Gallery on December 9 and which will remain on view through June 10. The three featured Buddhas hail from the collections of the Freer Gallery (together, the Freer and Sackler Galleries make up the Smithsonian’s Asian art museums), the Walters Art Museum (in Baltimore) and the Metropolitan Museum of Art (in New York City), respectively.

The Walters Buddha, the oldest of the three, dates to the twilight of the Sui Dynasty—the end of the sixth century AD. The other two were created in the days of the young Tang Dynasty, in the early seventh century. An incomplete fourth specimen, a Bodhisattva head from the Sackler collection dating to the eighth century, was also studied as a point of reference. All of these specimens were brought together for comparative analysis and exhibition thanks to the vision of Freer|Sackler conservator Donna Strahan, who had prior experience working with both the Met and Walters Buddhas.

Strahan had gotten the chance to do some laboratory work on those two sculptures before coming to the Smithsonian, and a preliminary discovery she made demanded follow-up research. “I had found that there is this partially burnt, ground-up bone in both Buddhas,” she said, mixed in with the lacquer to give it more texture. “When I mentioned that I thought it would be worth looking at the Freer Buddha” to see if it, too, contained bone, she says, the director of the Freer|Sackler Julian Raby said: “That sounds like an exhibition.’”

In order to put the show together, Strahan had to negotiate the relocation of the Met and Walters Buddhas to Washington, D.C.; owing to a provision in the Freer Gallery’s founding charter, the Freer Buddha may not be moved from its present home. “The Met and Walters Buddhas had never traveled,” she says, “and they’d been in their museums almost a hundred years,” so securing their release was a tricky business. “But since I’m a conservator and have examined these pieces and know them quite well, I felt quite confident that we could take care of them.”

Once a deal was struck and the Buddhas were gathered at the Freer|Sackler, intensive scientific analysis got underway. The first step was subjecting the specimens to x-radiography, a completely noninvasive means of drawing conclusions about their inner structure. X-ray scans revealed the presence of iron wire in the Buddhas’ ears, and of recesses in the backs of their heads that would once have accommodated halo attachments. X-rays also indicated concentrations of phosphorus and calcium—the makings of bone—in the layered lacquer paste coating the cores of the sculptures. Just like the Met and Walters Buddhas, the Freer Buddha incorporated animal bone as a thickening agent. Strahan’s hunch was correct.

Additional analysis entailed microscope inspection of minute samples taken from each of the three Buddhas. Scientists found that the same type of fabric—hemp—was used to separate the lacquer layers in all three cases. A cutting-edge gas chromatography technique developed at the Getty Conservation Institute shed additional light. “That gave us a lot more information,” Strahan recalls. “It wasn’t just the lacquer tree resin that was mixed in—there were also oils and sawdust. And we actually found human blood in our Bodhisattva head.”

The presence of blood in the eighth-century Bodhisattva specimen, not detected (as yet) in the three more complete, older Buddhas, raised many fresh questions for the research team. “We’re still investigating,” Strahan says. “We’re going to try and figure out: Was this just one layer? Was this just in one sculpture? Or is it a common addition?”

While she acknowledges that the precise function of the blood—ritual or practical—as well as its source will likely never be known, Strahan is optimistic that follow-up research might give her and others in the field a better sense of how widespread this technique was. She is also hopeful that ongoing assessments of the proteins found in the Met and Walters Buddhas could yet turn up additional insights into the bone and its role.

The story of the continuing research into the lives of these lacquer Buddhas is told in rich detail in the new exhibition, and the three main specimens—as well as a 3D-printed facsimile of the Bodhisattva head—are all on view for patrons to consider and compare.

What excites Strahan most about this show is the potential to engage both the scientific and artistic facets of viewers’ brains. “Science can really help us learn a lot more about art objects,” she says. “I hope by looking at materials instead of just the style, we can get people interested in how science helps us understand art.”

“Secrets of the Lacquer Buddha” is on view at the Sackler Gallery through June 10, 2018.