The excavation of the Jiuliandun Tombs in Zaoyang, Central China's Hubei Province, which began on December 20, has been widely hailed as the greatest archaeological find of the year.

"The tomb's owner could be the greatest general of the Chu Kingdom at the end of Warring States Period," said Guo Dewei, researcher of the Chinese Academy of Social Sciences.

The archaeologists also unearthed more than 1,000 bamboo slips (small strips or pieces of bamboo used as writing paper) in the tomb of the general's wife.

The slips look like pulpy noodles when excavated. They were black and mingled in the mud, although they were wrapped in plastic bags immediately after they were brought to light.

If they had been exposed to the air and had dried out, the one-centimeter-wide ancient bamboo slips would shrink to five millimeters in width and crack. While the words, which document a history of more than 2,000 years ago, would disappear.

Similar heart-aches have accompanied China's proudest discoveries: The terracotta warriors and horses of the Qin Dynasty lost their color upon excavation, the dazzling silk fabrics excavated at the Mawangdui Tombs of the Han Dynasty (206 BC-AD 220) are getting darker everyday, and the white marble lions standing before the Tian'anmen Gate are eroding in the air.

The job of preserving ancient cultural relics and preventing their destruction has fallen on the shoulders of the 1,000-plus Chinese experts who specialize in cultural relics preservation.

Even though these experts have equipped themselves with both traditional and some modern techniques, they face a daunting responsibility. There are now 12 million pieces of cultural relics in the collections of Chinese museums and more than 400,000 unmovable relics such as ancient tombs and buildings.

Moreover, "the technical level of cultural heritage protection is incompatible with the country's status as an ancient civilization," Shan Jixiang, head of the State Administration of Cultural Heritage, admitted.

Frontier Science

Fortunately, the situation is changing as Chinese scientists in cultural heritage protection, who currently have limited facilities and salaries, will soon have a research base of international standards, according to Ji Yimin, researcher with the Chinese Research Institute of Cultural Heritage and director of the institute's heritage preservation science center.

Ji said that the construction of a national central laboratory on cultural heritage preservation science is to start soon. The laboratory is expected to open in 2004.

The laboratory belongs to the national research center of cultural relic preservation science, which is also being built. The center will focus on research of both basic theories and also applied techniques on cultural heritage preservation science, said Ji.

Meanwhile a cultural heritage research center, which is to design cultural heritage protection plans, and an ancient building renovation center are also to be built. The three centers will be attached to the Chinese Research Institute of Cultural Heritage.

Funding of 150 million yuan (US$18.1 million) is to be allocated in three years by the Ministry of Science and Technology.

"The construction of the three centers will be an important phase in the history of Chinese cultural heritage protection," said Ji.

It is important because it will emphasize the application of science in cultural heritage preservation, said Gao Feng, researcher with the institute.

"Cultural heritage preservation science is a frontier science that has incorporated physics, chemistry, materials science, biology and information technology into cultural heritage preservation," said Gao.

It also promotes the application of modern technologies that are superior to traditional methods in many aspects of cultural heritage preservation.

For instance, to restore an ancient building, the conventional method is to fill the cracks in the wooden structure with cement.

The Anji Bridge of the Sui Dynasty (AD 581-618) in Zhaoxian County, Hebei Province, was repaired in the 1950s with steel and cement and its structure was therefore changed after the renovation, according to Huang Kezhong, researcher with the Chinese Research Institute of Cultural Heritage.

In the second facelift of the Potala Palace in Lhasa, which started this year, experts abandoned the use of cement, added chemicals to the hardened soil that formed the palace roof, and successfully prevented it from leaking, without changing the building structure.

Despite their apparent advantages, modern technologies were seldom used in cultural heritage protection in China until the 1980s because of their relatively high cost and lack of local expertise.

Gradual Progress

Since the 1980s Chinese experts have applied modern materials science and analytical techniques in projects such as the renovation of the Chau Say Tevoda in Cambodia, the preservation of the Mogao Grottoes in Northwest China's Gansu Province and the preservation of the colored paintings on the terracotta warriors and horses of the Qin Dynasty in Xi'an, Northwest China's Shaanxi Province.

Research into technologies to preserve metal, wooden, bamboo and lacquer artifacts, frescoes and silk fabrics has also been carried out by institutions such as the Chinese Research Institute of Cultural Heritage, the National Museum of Chinese History, the Nanjing Museum, the Dunhuang Academy and the Shaanxi Archaeological Research Institute.

Among the leading programs in the field is the study on batch drying waterlogged wood, carried out by Ji Yimin and his team. They applied their research to the preservation of more than 170,000 bamboo slips excavated in 1996 in Changsha, capital of Central China's Hunan Province.

The bamboo slips, which attracted worldwide attention because of the number retrieved and the millions of characters on them, rewrote the history of the Kingdom of Wu (AD 222-280) in the Three Kingdoms Period (AD 220-280).

To preserve the waterlogged bamboo slips scientists replaced the water molecules in the slips with alcohol molecules, then replaced the alcohol molecules with ether molecules before freeze-drying the slips.

"The research can be widely applied since most bamboo and wood artifacts are waterlogged when excavated and would be seriously damaged if exposed to air without pre-processing," said Gao Feng, a member of the research team.

During the recent 2002 International Convention on Conservation and Preservation of Cultural Heritage, leading scientists from China, Japan, the Republic of Korea and Germany pledged international cooperation on research into cultural heritage preservation science.

Su Boming from the Dunhuang Academy gave a presentation at the convention of the Sino-American research project on the causes of the deterioration of frescoes in the No.85 Cave of Mogao Grottoes.

A number of analytical techniques such as X-ray diffraction, polarized-light microscopy, scanning electron microscopy and gas chromatography/mass spectrometry were used to study the pigments and the ground, earthen support and organic binding material, during the project.

Scientists concluded that much of the damage to the frescoes could be traced to the presence of sodium chloride, a natural salt, in the earth plaster and paint layers.

Despite the advances made, cultural heritage preservation science is still an emerging field in China, said Gao Feng.

System of Standards

"This frontier science doesn't have its own standards. For instance, to measure the content of water, the PH value and other important indices of the materials of ancient buildings, we have to borrow standards from the building industry," he said.

"But the standards applied for an ancient building should be much different from those for a modern skyscraper."

Gao also stressed that standards should be developed to evaluate renovation projects.

"We say an ancient building should look old after renovation, but there is no index as to what is 'looking old.' Today it's judged by the experts' subjective opinions."

He said the new national research center of cultural heritage preservation science will focus on establishing a system of standards to examine the materials used in, and on cultural relics and sites.

Cooperation with archaeologists is also badly needed if cultural heritage preservation science is to be widely put into practice.

"Experts on cultural heritage preservation science are rarely seen at excavation sites. The archaeologist excavates the relics, the storekeeper of the archaeological institute prevents the relics from being stolen, and often no one prevents the relics from being damaged by natural forces on excavation," said the Beijing-based Guangming Daily.

Gao Feng expected the new research center and laboratory under construction would help develop skills in cultural heritage preservation that are lacking in China. "We'll soon see qualified professionals in heritage preservation working with excavation teams," said Huang Kezhong.

"The professionals will be at the site to stop the excavated relics from corroding, keep their original colors and equilibrium between temperature and humidity, and prevent the relics from being damaged by lights or radical changes in temperature or humidity during transportation."

Huang also stressed that the new science of cultural heritage preservation would also draw on traditional knowledge.

"Our ancestors have come up with thousands of inventions in past millenniums," he said.

"For instance, the 0.05-millimeter-thick coating of the Longmen Grottoes has successfully fought wind erosion for more than 1,000 years, and we still don't know what it is made from."

(China Daily December 30, 2002)