Woodblock printing
Woodblock printing, invented by about the 8th century during the Tang Dynasty, worked as follows. First, the neat hand-copied script was stuck on a relatively thick and smooth board, with the front of the paper, which was so thin that it was nearly transparent, sticking to the board, and characters showing in reverse, but distinctly, so that every stroke could be easily recognized. Then carvers cut away the parts of the board that were not part of the character, so that the characters were cut in relief, completely differently from those cut intaglio. When printing, the bulging characters would have some ink spread on them and be covered by paper. With workers' hands moving on the back of paper gently, characters would be printed on the paper. By the Song Dynasty, woodblock printing came to its heyday. Although woodblock printing played an influential role in spreading culture, there were some significant drawbacks. Firstly, carving the printing plate required considerable time, labour and materials; secondly, it was not convenient to store these plates; and finally, it was difficult to correct mistakes.