How it began
Movable-type printing was invented between 1041 and 1048 by Bi Sheng, described by the Asian Art Museum as a common man who was highly experienced in woodblock printing, and by Britannica as an alchemist. The invention is known from the account of the Song scholar Shen Kuo, whose Dream Pool Essays describe the method. It was devised during the reign of the Song emperor Renzong.
Before it existed
Books in China were printed from wood blocks, each carved with a whole page of text. The method worked but was slow. In 971, at the beginning of the Song dynasty, a project to print the Tripitaka, a collection of Buddhist scriptures, from wood blocks took twelve years to complete its 1,076 volumes. A block could print only the page carved on it, so every new text meant carving again.
How it works
Bi Sheng made one type for each character from an amalgam of clay and glue and hardened the types by baking. He composed a text by placing the types side by side on an iron plate coated with a mixture of resin, wax and paper ash. Gently heating the plate and letting it cool fixed the types in place, and a wooden board was pressed down on them to make sure they were level. The tops of the types were then inked and printed from like a wood block. Reheating the plate released the types for reuse.
Who pushed back
The new method did not displace the old one. The Asian Art Museum notes that woodblock printing remained popular in China for several centuries after Bi Sheng's invention. Britannica, discussing later European attempts at separately carved type, points out a general weakness of such type: it was fragile and wore out at least as quickly as blocks carved with a whole text.
What lasted
Bi Sheng's types established the principle of composing a page from separate, reusable characters. The History of Information records the invention as the first movable type, made between 1041 and 1048. The American Association for the Advancement of Science notes that the account preserved by Shen Kuo describes movable type about four centuries before it was developed in Europe.
