Chinese researchers said recently that they had found ways to preserve color of the terra-cotta warriors in the tomb of Qin Shihuang, the first emperor to unify China.

"The key problem in protecting the warriors was resolved," said Wu Yongqi, curator of the Qin Shihuang Terra-cotta Warriors and Chariots Museum.

Dubbed one of the eight wonders in the world, and the most splendid archeological find of the 20th century, the Qin Shihuang tomb was accidentally discovered in 1974 by local farmers while they were digging a well.

Nearly 8,000 life-sized terra-cotta warriors and horses along with tens of thousands of pieces of weaponry have been uncovered from three pits, where the terra-cotta warriors and horses have slept for almost 2,200 years.

For various reasons, most of the warriors and horses, colorfully painted at the time they were created, had lost their vivid colors when they were unearthed from the tomb.

Researchers said that the lacquer on the terra-cotta warriors is highly sensitive to temperature changes, and the warriors suffered further from mildew and drying out when they were excavated from the damp earth, causing lacquer to shrink.

Over 20 different reinforcing agents and 19 shrink-resistant materials have been tried and scientists have come up with a liquid mixture of polyurethane to protect the lacquer.

Using an advanced technology for stabilizing the lacquer layer, several warriors painted in dark red or green were found to have remained in stable condition for many years.

The scientists succeeded in protecting another several hundred warriors by using the same method.

But today, the scientists are still faced with growing problems in keeping the soldiers' youthful looks, and they have been forced to scale back excavations, said Wu.

Other problems threatening the warriors include ground water and the risk of earthquakes in an area that has already seen numerous large tremors in the past.

(People's Daily December 23, 2003)