In 1988, although Neville Agnew was enthralled by the Dunhuang Mogao Grottoes in Northwest China's Gansu Province at first sight, he knew little about these murals. But it was he who later developed a modern scientific methodology for the conservation of these aged art treasures.
More importantly, he was also the first drafter of a set of principles concerning the conservation of the country's heritage.
"The grottoes were big! That was my first impression being there," recalled Agnew, an illustrious specialist with the Getty Conservation Institute (GCI) in the United States.
But what impressed him more later on were those deteriorating ancient murals. "Some of them were hanging on the wall, ready to fall off; some were eroded by salt that oozed from underlying rocks," said Agnew, 68, who has degrees both in chemistry and geology.
His first 10-year involvement in the grottoes conservation was to deal with the serious sand and wind in Dunhuang, which have been threatening the murals for centuries.
Later in 1998, Agnew was designated a leading specialist for a new joint program initiated by GCI and the Dunhuang Academy in Cave 85, one of 750 carved out of the sandstone cliffs along the Daquan River more than 10 centuries ago. Among all the caves, 492 have murals.
He and his colleagues come to China twice a year, staying for three to five weeks each time.
US conservation specialist Neville Agnew works on the protection of murals at Cave 85 at the Dunhuang Mogao Grottoes in Northwest China's Gansu Province in 2002.
Instead of jumping into some rescue work, the scientist, who is experienced in adobe preservation in different countries, adopted a more sustainable approach by documenting the paintings.
The team, consisting of more than 20 professionals from both countries, took 500 photographs of the murals, stuck plastic on the photos and indicated problems with each mural on the plastic by developing a set of legends.
"It took us months to complete the diagnosis," Agnew said.
The murals in Cave 85 were painted in AD 868 with mineral and plant pigments. After chiseling out chambers in the cave, ancient artists covered the conglomerate with mud from the nearby river and drew on the mud.
"Years passed," Agnew said. "The mud dried and shrank, creating hollows between paints and the rock beneath. Paintings, therefore, came to be suspended on the wall, ramshackle."
Another main threat to these murals is the salt from the rock, which is a problem for all buildings made of stone.
"Increasing humidity inside the cave leaches the salt from the rock," Agnew said. "The salt then transfers slowly to the mud, crystallized and bursting paints open."
To solve the two problems, Agnew and his team members conducted a thorough analysis by making numerous laboratory experiments, which however was unfamiliar to Chinese experts at that time.
Wang Xudong deputy director with the Duhuang Academy, who has cooperated with Agnew in the project since the 1990s recalled: "We used to rely on experience to rescue these flaking paintings. It was Agnew who told us what a scientific solution is like."
To find the right material to fill into the hollows between the paint and the wall, Agnew led his team to list 80 different formulas after analyzing the paint, the rocks and the salt.
Then came the painstaking laboratory experiments in search of a grout that was "strong, light and shrinks little."
Both Agnew and Wang recollected clearly a two-week argument between Chinese and American experts about the grout selection.
"That was impressive because it exemplified what a big revolution Agnew brought to our management," Wang said. "We learned that a friendly academic argument would simply improve the work."
The Chinese side insisted that the grout must be something that is also contained in the murals, but Agnew argued that new materials must be added to the grout to increase coherence, provided they proved harmless to the paints.
Finally through experiments, they agreed on a formula that consisted of egg white, clay, water and some chemicals.
After injecting the grout into the holes, the "rescue team" developed a poultice to cope with salt and humidity. Then they hoisted scaffolds and coated the murals with a Japanese tissue, then clay, sponge and a wood board, layer after layer, pressed with a designed moderate force.
It took the team about seven years to complete the treatment, but Agnew certainly appreciated the time they spent on the work.
"We don't make instant recipes," he said. "What is the point of that? I don't want to waste my time if the rescue can last for only some years.
"We shall develop a methodology that can apply to the future work as well as other heritages."
Starting from 1997, Agnew began to participate in drafting the Principles for the Conservation of Heritage Sites in China, a set of guidelines for the conservation and management of cultural sites. He integrated his experience working in Cave 85 into the principles.
"We must be aware that heritage is valuable historically, artistically and scientifically," Agnew said. "So, anything we do to them will probably harm their values. Thus, we conservation workers need to adopt careful study and tests to minimize the impact."
In his opinion, management is the top priority in a successful conservation. "It is like running a hotel, which requires good co-ordination among all parts of the work to satisfy your guests," Agnew said.
To promote the principles, Agnew, on the one hand, has been involved actively in training advanced young mural conservation specialists. He persuaded GCI, the Courtauld Institute of London University, Lanzhou University and the Dunhuang Academy to launch a joint program in the training.
On the other hand, Agnew has helped initiate regular workshops for Chinese conservation staff. A new group of 90 heritage specialists nationwide will leave for Australia and the Mogao Grottoes in May to examine how to conserve relics. "After they return, they will start writing a training manual for the rest of the staff in the country," he said.
Agnew also extended his experience in Dunhuang to the conservation of the Yungang Grottoes in Shanxi Province and the Chengde Summer Resort in Hebei Province, both in North China. In the meantime, his work in Cave 85 is continuing with a more comprehensive investigation.
"We are working on the control of the tourist flow," he said.
Again, the team are working scientifically. They are measuring the ventilation, calculating humidity and observing tourist behavior.
In return, the lasting friendship with China has aroused Agnew's interest in Chinese culture. He started learning Chinese years ago. And each time he spent time in the country, he bought some Chinese artefacts, especially porcelain.
Wang, of the Dunhuang Academy, touted him as an open-minded man with a full respect for foreign cultures.
"Without that respect," Wang said, "we wouldn't be able to maintain such an unfailing collaboration."
(China Daily April 17, 2006)