Change in approach

陈小将

Experts noted that cave temples, often located in remote mountainous areas and exposed to the natural environment, are difficult to protect and manage, as they frequently face threats such as water damage, earthquakes, unstable rock foundations and weathering, as well as human-induced damage.

"Despite the difficulties, China's efforts to protect its cave temples have endured for eight decades," said Su Bomin, director of the Dunhuang Academy. "We have continuously explored technologies and accumulated experience in restoring the Mogao Caves, developing a comprehensive set of programs that have been applied not only in domestic grottoes but also to sites overseas."

Su said that the approach to protecting China's cave temples is currently experiencing a leap from a "rescue restoration" mindset to one focused on "preventive protection".

Hang Kan, director of the Yungang Research Institute, said that in recent years, professionals have intensified their efforts in the digital collection of information from the caves of the Yungang Grottoes, striving to "seize the information at the moment".

"Grottoes are changing every day, and so is the information they carry. We want to capture every moment to preserve as much information as possible," said Hang. He added that they have collected information from 80 percent of the caves, which will serve as a reference for their long-term protection.

On the other hand, restorers are actively exploring new technologies and materials for cave temple restoration. For example, in the 1970s, epoxy resin was frequently used in restoring cultural relics in caves due to its strong adhesion, excellent versatility and chemical resistance, making it an advanced new material at that time.

However, after decades of use, professionals have discovered that epoxy resin materials are not good enough, as they age and deteriorate under high temperatures. Therefore, they are developing new materials.

Experts from Chongqing University are exploring a way of using microorganisms in the restoration of cultural relics as an alternative to epoxy resin. By introducing specific microbial strains under suitable environmental conditions, bioadhesives can be synthesized, and these can then be applied to reinforce cracked relics, offering benefits such as greater compatibility, non-toxicity, environmental friendliness and stronger weather resistance, according to Hang.

"The protection of cave temples is not a once-and-for-all project. With changes in time and climate, new problems arise, bringing fresh challenges and prompting us to continuously seek new materials, innovative ideas and advanced technological methods for their preservation," he said.