A retired teacher in northwestern China has found a novel raw material for making paper－poop from the giant panda.

Liu Xiaodong, 68, has had a paper-making workshop in Qiliang village of Shaanxi province since stepping down as the local primary school principal in 2008.

Two years ago, he began experimenting with panda excrement, mixing it with varying quantities of mulberry tree bark, wild kiwifruit vines and spring water to make paper. On Nov 17, he finally cracked it.

He got the idea while wandering on Qinling Mountain, just south of his village, which is a major habitat for the endangered giant panda.

"Every day, a panda eats about 35 kilograms of bamboo, but it absorbs only 30 percent of the nutrients from the bamboo," said the craftsman, who runs Cai Lun Paper-making Cultural Garden, suggesting that 70 percent was ending up in their waste.

"I saw a lot of panda poop there, and I wondered if I could make paper with it."

He got in touch with a panda breeding and protection base on the mountain to discuss his idea and, to his surprise, the experts there were keen to help.

Zhou Juanhua, who runs the facility, said the animals' waste was previously buried or burned, so he saw Liu's paper-making proposal as an environmentally friendly alternative. "We offered to provide fresh droppings," he said.

Liu Lijie, 66, who helps in Liu Xiaodong's workshop, said he did not understand the idea of turning panda poop into paper at first, "but his dedication touched me, so I stuck with him to study it further".

"By using the animal waste, we don't cut down bamboo or other trees, or use any chemical additives in the paper-making process, which protects our environment," he added.

Qiliang village, about 60 kilometers southwest of Xi'an, Shaanxi province, is believed to be the birthplace of paper-making, with the invention credited to Cai Lun (61-121), a eunuch, during the Eastern Han Dynasty (25-220).

Since ancient times, families in Qiliang have run paper-making shops or been trained in the skill.

Liu Xiaodong, who was born in the village, said he opened his workshop because he wanted to pass on the traditions to future generations.

His tools are all century-old items, including trolleys, water tanks, hand hay cutters and the double-edged fine-toothed comb for paper fishing, giving a sense of passing through time and space.

"The modern paper-making technology uses industrial caustic soda, but we still use the process of sousing so that the water we use for paper-making is safe for keeping fish in afterward," Liu Xiaodong said.

Paper-making is regarded as one of the four great inventions of ancient China, along with the compass, gunpowder and the printing press.

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