[Photo by Jiang Dong/China Daily]

Meanwhile the number of restoration professionals has grown from less than 100 in 2007, when the preservation project started, to more than 1,000 today, according to Zhang Zhiqing, the national library's deputy director.

Zhang is also the deputy director of the National Center for Preservation and Protection of Ancient Books.

He says these professionals have a master's degree in ancient book preservation, jointly offered by the center, three universities and the Chinese Academy of Social Sciences, a think tank.

He adds that 22 national-level restoration studios have been set up across the country, where traditional skills to preserve books are passed on from elderly masters to younger apprentices.

"To be a professional, one needs patience and persistence," says Zhang. "It takes about five years for a learner to work independently. He or she will then need at least two decades to be a real master.

"It's a challenging job," he says, adding that a steadily growing pool of professionals forms the base of the preservation project.