The Imperial Palace of the Qing Dynasty (1644-1912) in Shenyang, capital of Liaoning province, is undergoing annual renovation. With a budget of more than 2 million yuan ($315,800), the refurbishing of the palace — the second-largest royal complex in China after the Forbidden City in Beijing — is expected to be completed by the end of June.

Built in 1625, the palace, also called Mukden Palace, was the residence of Nurhaci and his son Hong Taiji, founders of the Qing Dynasty. Shenyang was later used as an accompanying capital after the dynasty moved its capital to Beijing in 1644.

Li Shengneng, deputy curator of the palace, said that more than 100 experienced relic building repairers have participated in the renovation, and are trying to maintain the palace's grandeur as it was. "This is the largest scale maintenance of the past few years. Some of the buildings don't need to be repaired every year."

All materials were drawn from their original sources, and applied in the original craft, he added.

High scaffolds have been set in front of some buildings, accompanied by green nets for protection. Repairers were removing dust and repainting areas where paint had chipped.

Relic building maintenance is not an easy job. For the repairers, it takes great patience and care. For example, there are 12 procedures to repair the ground layer (the base of mural) alone.

Workers should take off the old layer and paint foundation oil on the first layer, said Kong Han, an ancient craft veteran with more than 20 years' experience. Then, fine hemp rope saturated with oil should be put on the layer. "No single procedure can be omitted," Kong said.

"It takes at least five hours to make the special paint, more than one month for the first layer of paint to dry and another 15 days for the second layer to dry. One omission may force a worker to start over from the beginning," he added.

However, not all the ancient techniques are fit for today's needs.

"Sometimes adding in some modern skills in specific areas can complement the drawback of ancient ways," said Wang Qingxi, who specialized in civil engineering.

"Because the weather is usually wet in the spring in Shenyang, we add modern waterproofing during fixing procedures. Thus, it can solve water seepage problems," he illustrated.

The repairs to the imperial palace can be traced back to the years of Kangxi Emperor (1661-1772), and different periods have different ideologies of renovation.

According to Li, in 1970s and 1980s the floors of the palace were replaced by limestone but later changed back to bluestone after a major overhaul in 2003 to restore its original appearance.

"We try our best to make the buildings original looking," he said.

Contact the writers at liuce@chinadaily.com.cn and wuyong@chinadaily.com.cn