Zhao Yishen is bent over, his eyes staring at the woodblock. Holding a chisel in his right hand, he guides it forward steadily and precisely across the woodblock using his left hand.

To engrave the woodblocks, the 33-year-old artisan has to hold this position for six hours.

He has been carving woodblocks since 2012.

"It feels good and looks beautiful when a Chinese character slowly appears on the woodblock under your chisel," says Zhao.

Zhao is now the only full-time carver working at the Zhuyu Shanfang studio, a workshop that focuses on creating woodblock-printed books in Beijing.

Each carved woodblock has ink applied and goes on to print a text onto hundreds pieces of paper.

Zhao carves around 20 Chinese characters each day, which means it takes him one year or even longer time to complete a set of woodblocks suitable for a whole book.

As a teenager he loved to read ancient Chinese books in the library, and the curiosity of how the books were made led him to get a job at the Guangling Guji ancient books woodblock printing studio in Yangzhou, Jiangsu province, in 2011 after graduating as a law major from college.

Block printing was enlisted as a UNESCO World Intangible Cultural Heritage in 2009. Zhao was introduced to one of the technique's masters, Chen Yishi, in 2012 and started to learn the skill from him.

"The first step is to learn how to sharpen your chisel," says Zhao. "The quality of the carving depends on the chisel. It's like using a pencil - after using it for a while, you need to sharpen it again."

The woodblock must be approached at a certain angle that is deep enough to show up the characters and also to ensure the cuts are deep enough - but not too deep.

He first practiced the horizontal strokes time and again, followed by vertical ones. For a whole month, he just carved these two types of strokes.

Only when he is satisfied that he has the right approach will he begin the real work.

"I must make sure each line on the wood is exactly at the same depth and angle. It must be as accurate as a machine," Zhao says.

Before he goes near the wood, he'll have the characters vertically arranged on paper first.

Then Zhao puts the paper, face down, onto the wood after brushing oil on the paper. This helps to transfer the image of the characters onto the block.

Once the carving is finished, the woodblock is smeared with red ink and paper pressed onto it.

The red ink version is for initial proofreading. Then blue ink is brushed on for more proofreading before black ink is finally applied and it is ready to print.

In Zhao's mind, the inked woodblock is a work of art.

After a year of learning from Chen, Zhao found a job at Zhuyu Shanfang in 2013, where he perfected his engraving skills. His carved woodblocks have been used for several books over the past six years.

"I just learned the basic skills, but to master it, I still need years of practice," says Zhao. "A good craftsman can carve an entire book with every single character aligned evenly."