Restoring Emperor Qianlong's long-sealed-off lodge Juanqinzhai required an epic journey throughout the country. The Palace Museum had to find the last practitioners of the virtually vanished techniques used to fashion the building about two centuries ago.

Bamboo craftsman He Fuli recalls feeling anxious when called upon to help.

"The work was all about decoding ancient secrets to fix the damaged relics," the 69-year-old explains.

"Upon entering Juanqinzhai, I felt more like an archaeologist than a craftsman."

And He says that feeling never left him during his three years working on the site.

Bamboo craftsman He Fuli repairs a bamboo screen at Juanqinzhai, in the Forbidden City. Provided to China Daily

Wang Shiwei, deputy director of the Historical Architecture Department of the Palace Museum, explains: "Many of the techniques used at Juanqinzhai were lost. We had to do a lot of research to see if we could rediscover them to restore the building."

That's part of the reason the restoration lasted six years.

One of the greatest challenges was fixing the worn bamboo carvings. Experts headed to Zhejiang province's Dongyang, where bamboo craftsmanship has thrived for centuries, to seek someone up to the task.

After two failed journeys, they placed a newspaper advertisement as a last resort.

He's son-in-law spotted the advertisement, brought it to He, and he called.

While He and his team earned full marks on the exam, it took four months before the conservators responded.

He became the fourth generation in his family to craft bamboo, at age 15. But he had little inkling of the challenges he would face when he joined the restoration in 2004.

Qianlong loved southern China's bamboo thread marquetry and inner-skin bamboo carvings, so they were used extensively in his lodge.

Carving the bamboo inner skin requires several steps, including softening, smoothing and polishing before the skin is etched and the pieces glued on furniture.

Marquetry requires slicing and weaving bamboo strips into geometric patterns sometimes inlaid with jade. But Juanqinzhai's pieces were badly damaged over centuries of neglect.

While He had long practiced these otherwise mostly dead art forms, his work had long aimed at the commercial market and, consequently, worked with styles far removed from those used for the emperor's lodge centuries ago.

"I'd forgotten or had never learned many of the necessary skills," He says.

His task was massive.

All of the bamboo filaments in the theater's stage had fallen out.

He also had to work around such challenges as the prohibition of fire in the Forbidden City. His solution was to boil pigment-coated strips with an electric kettle, rather than roasting them on an open flame.