7. Painting The Terra-Cotta Army
Researchers in China believe they’ve solved the 2,200-year-old mystery behind the polychrome paint of the famous Terra-Cotta Army.
Discovered back in 1974, the Terra-Cotta Army is a vast collection of almost 9,000 statues representing soldiers, chariots, and horses buried with the first emperor of China, Qin Shi Huang, to serve as his imperial guard in the afterlife. When they were found, some of the sculptures still contained patches of colorful pigment and minute remnants of binding material, something exceedingly rare in statues buried underground in water-saturated sediment for over two millennia. The pigments have previously been identified—inorganic compounds such as cinnabar, azurite, and malachite—but the bonding agent and the precise method used to paint the Terra-Cotta Army remained elusive until now.
To find their answer, Chinese scientists used a state-of-the-art technique called matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). The high levels of sensitivity provided accurate results despite trace amounts of bonding agent. The results were then compared to “artificially aged” samples of period-accurate adhesives through peptide mass fingerprinting, which identified the proteins in each specimen.
According to the study, ancient Qin dynasty artists first coated the sculptures in one or two layers of lacquer obtained from a Toxicodendrontree, commonly known as the Chinese lacquer tree. Afterward, they either applied polychrome layers directly or, in most cases, used binding media made out of animal glue.