During the Qingli period (1041-1048) of the Northern Song Dynasty (960-1127) under the reign of Emperor Renzong, there was a man named Bi Sheng who often went to the printing workshop to watch and study how to print books. At that time, woodblock printing was widely used. The characters were cut in relief on a board before being printed on paper. Bi Sheng found that if the book did not need to be reprinted, then those particular printing plates would never be used again; carving woodblock plates was hard work and was very time consuming; if any mistake was made, it was difficult to correct it without discarding the whole plate. So, Bi Sheng decided to try to improve this system.
One day, Bi Sheng was looking at some small clay figures -children, animals, knives and swords. Suddenly an idea came to his head. Wouldn’t it be easier to cut each character on a piece of clay and then place the pieces in order on a board for printing? In this way, the pieces could be used repeatedly.
Bi Sheng set to work. He carved the characters needed for a book on some pieces of clay. Each character was cut several times each and certain common characters were cut over twenty times each. After finishing the carving, he fired the pieces to harden them. At last his movable types were ready.
Bi Sheng put the types on an iron plate that was covered evenly with rosin, wax, and an ash-like material. Then he placed the plate near the fire to warm it. When the paste was slightly melted, he took a smooth iron plate and pressed it over the surface, so that the block of type became as even as a whetstone. Then, he spread ink on the in-type characters for printing. When the printing was finished, he again put the plate over the fire to melt in
rosin, wax, and ash and then he pushed the types off from the plate. The types could now be used for a number of printing jobs.
If one was to print only two or three copies, this method would be neither simple nor easy. But for printing hundreds or thousands of copies, it was marvelously quick.
Bi Sheng constantly refined his printing techniques and made this invention more and more sophisticated. Afterwards movable type printing spread far and wide and changed the world.
