XI'AN, Feb. 8 (Xinhua) -- While standing in a damp and moldy tomb, Yang Wenzong felt overwhelmed gazing at the murals along the walls that date back more than 1,200 years.

Despite the depredation of time, the colors and lines of the frescoes are still recognizable, while some of the delicate paintings are incomplete due to the destruction of tomb robbers years ago.

Yang and his team were conducting a salvage excavation in the 12-meter-deep tomb decorated with the delicate and peculiar murals. The tomb's owner, Han Xiu, is a well-known chancellor during the Tang Dynasty (618-907).

With bated breath, Yang used a brush to reinforce and repair the incomplete paintings after early-stage preparations.

Since graduating from Northwest University in 1984, Yang, 58, has devoted himself to cultural relic protection and restoration. In his eyes, weather-beaten cultural relics are like "elderly patients," and he is a "doctor" who treats them.

"The restoration of tomb murals starts from transferring them," Yang said. "Most of these paintings, like elderly patients, produce 'symptoms' including cracking and mildewing, so a process of reinforcing is needed before conducting an 'operation'."

Restoring tomb murals is time-consuming and monotonous.

A breeze or a bright light can cause damage to the murals in the tomb. Some ancient tomb frescoes seem to be well preserved, but the cement materials used in the paintings were completely decomposed after thousands of years.

"Even a slightly heavy breath may cause the pigments to fall off, as the dyes are attached to the surface of the murals in the form of powder," he said.

To improve the mural lift technique, Yang and his colleagues have conducted thousands of trials, and gradually formed an industry standard in the protection and restoration field of tomb frescoes.

The rescue excavation of the tomb, which began in 2014, is a fresh example that the country's heritage conservation experts attempt to protect murals in an all-round, scientific and systematic way.

It took nearly two years to transfer the murals, and restoring them is an even longer journey. Some are still being repaired today.

"It's a profession that requires a great deal of patience and endurance," Yang said, adding that a single movement can be repeated thousands of times to remove dirt rust from a fresco without damaging a layer of paint.

In the past three decades, Yang has renovated thousands of pieces of cultural relics, including ancient murals, bronze, ceramics, porcelain and gold and silver wares.

Many of them are big names. Yang participated in replicating the Bronze Chariot and Horses No. 2 unearthed in the mausoleum of Emperor Qinshihuang, world-renowned for the army of terra cotta warriors.

Yang frequently walks around the exhibition hall of mural paintings of the Tang Dynasty in the Shaanxi History Museum, an underground hall housing nearly 100 pieces of exhibits unearthed from the imperial tombs and the tombs of nobles. Yang has been involved in the restoration of many masterworks there.

"We are 'relic doctors.' When you realize what you are rescuing is priceless, a sense of accomplishment emerges," Yang said. "Nothing else can replace that feeling." Enditem