This photo taken on Aug. 23, 2023 shows a piece of the painted Terracotta Warriors at the Emperor Qinshihuang's Mausoleum Site Museum in Xi'an, northwest China's Shaanxi Province.

"We are the Terracotta Warriors specialists, and this room is a 'hospital' for the relics in the museum," said Lan Desheng, an expert in the restoration of cultural relics with the Emperor Qinshihuang's Mausoleum Site Museum.

Archaeological research shows that pigments have been found on the Terracotta Warriors. The painted layers of the Terracotta Warriors are very fragile. Once unearthed, with the changes of humidity and temperature, the surface quickly dehydrates and the painted layer comes off. In addition, microorganisms, soluble salts and other factors also cause the color fading.

According to Lan, shortly after unearthing, each painted Terracotta Warrior must go through X-ray detection, ultrasonic scanning, 3D images acquisition and other procedures. Staff members clean and restore the pieces of the painted Terracotta Warriors using slim bamboo slips, scalpels, small brushes, etc. Every Terracotta Warrior also has its own ID. In recent years, Lan and his team have completed the restoration of more than 140 Terracotta Warriors.

Discovered in 1974 and listed as a world heritage site by UNESCO in 1987, the army of Terracotta Warriors was built by Emperor Qinshihuang of the Qin Dynasty (221 B.C.-207 B.C.). [Xinhua/Li He]