How to investigate without harming the precious art?
Scientists pitched in to help figure it out.
Cutting-edge analytical techniques helped solve the mystery — and revealed more about the object’s history.
To get answers, conservators had to consent to giving up parts of the irreplaceable 26-inch art in the name of science. An international team of researchers analyzed 11 tiny drilled samples that weighed just a few milligrams apiece. Taken from different sites on the terracotta horse, the samples underwent a battery of different tests.
By analyzing everything from the samples’ chemistry to their molecular makeup, scientists made the most of the tiny piles of powder.
One technique, X-ray powder diffraction, studies how an X-ray behaves when it’s trained on a mineral or other substance that has been ground into powder. Different materials bend the rays in different ways, and the technique can help identify blends of substances or the makeup of even very small samples.
Other techniques included Raman spectroscopy, which looks at how the light of a laser beam scatters when it hits the sample.
The researchers describe their investigation in the journal Heritage Science.
The tassel wasn’t made from terracotta, the scientists learned — it was plaster tacked on with animal glue. Other tassels on the horse’s saddles revealed evidence of multiple repairs over the generations.
Ultimately, discovering the tassel wasn’t original led the museum to remove it.
The study will help conservators better decide how to keep the horse in good shape. In a news release, Pietro Strobbia, a University of Cincinnati assistant chemistry professor who led the research, says he’ll continue analyzing objects for museums throughout the Midwest.
The restored statue, and other depictions of horses throughout China’s long history, will be on display at the museum beginning Oct. 7.