When Li Yunhe traveled from his hometown in Shandong province to visit his uncle who worked with the restoration team of Dunhuang's Mogao Grottoes in 1956, he was offered a job that very few people in China had done before.

During the visit, he met Chang Shuhong, who later became the first director of the Dunhuang Academy, and Chang persuaded the young man to stay and join his team as a fresco art restorer.

From then on, Li, who always wears blue overalls, started his daily routine getting in and out of the caves with a torch in his hand and a toolbox strapped to his back, which contains injectors, rubber suction tubes and other necessary items to protect the murals. His job responsibilities include "curing" typical mural diseases such as flaking, detachment and blisters.

Over the past six decades, Li, who has gradually grown into a top expert in the field, has repaired over 4,000 square meters of area covered by the murals inside the caves and more than 500 sculptures. He has also pioneered several methods in the protection of relics.

On Jan 18, Li was named by the All-China Federation of Trade Union as a "craftsman of great power".

Li, 86, is the oldest among the 10 people awarded, whose expertise varies from geological surveys, electrical welding, oil drilling and other fields. The awards were based on seven months of both public online voting, and offline voting by a group of experts.

It took Li five years of learning and practicing to master all the steps and basic skills in painting and carving.

Finally, he was asked to repair the murals in Cave No 161 in Dunhuang-a project covering 60 square meters.

"When I first entered the cave, a gust of wind blew in. Suddenly, the murals were peeling off just like snowflakes fluttering in the air," he recalls. "If we didn't take action, the paint would all come off."

Since 1962, he spent more than 700 days in that cave, pasting the pieces back to the wall inch by inch.

According to Li, each step of mural restoration requires patience, care and concentration.

For example, when repairing an area where the paint has come off, the repairer should first use a rubber suction bulb to blow away the sand and dust on the flakes and then use a brush to clean the wall surface.

"Sometimes we use small devices instead of a rubber suction bulb because even the gentle blowing could be strong enough to destroy the paint," he explains.

"Although the project took a long time to complete, it laid a solid foundation for the future improvement of relic protection techniques," says Li, adding that the cave was the first one that Dunhuang Academy repaired independently.

With constant innovation in tools, materials and technologies, Li and his colleagues have explored better methods for mural restoration and protection over the years. To date, he has been invited to support important restoration work of relics at Beijing's Palace Museum, the Potala Palace in the Tibet autonomous region, the Lingyin Temple in Hangzhou city and other places.

In 2015, he took his team to the Yulin Grottoes and started to renovate a 24-meter high Buddha statue.

Time files. And the experienced craftsman, still in his blue clothes, climbs up and down scaffoldings with a torch, a toolbox and a pair of presbyopic glasses (that he didn't need before). He has spent his long career conserving ancient art treasures in China.

Li believes that love for such artwork is more important than just learning restoration skills.

"Artworks are alive," he always reminds his team members.

His long-term passion for mural restoration has also influenced his family.

While Li has spent more than 60 years illustrating the spirit of a real craftsman, his grandson Li Xiaoyang, who joined Dunhuang Academy after graduating from the Royal Melbourne Institute of Technology University in Australia in 2011, is carrying his work forward.

"When I was a boy, I often heard my grandfather talk about how to repair murals. I feel so lucky that I myself can now restore these murals," says the 30-year-old, adding that the photos of mural before and after restoration give him a strong sense of satisfaction.

Zhang Qiuting contributed to this story