Bi Sheng

A midpoint, not a record

The year 1045 does not appear in the source. Shen Kuo's later account places Bi Sheng's invention somewhere in the Qingli reign period, 1041–1048, without identifying a year or any particular day.

1045 is only a midpoint convention inside that eight-year range. Shen wrote decades after the invention, although his family reportedly possessed the original type.

How the clay type worked

Bi Sheng carved individual characters in sticky clay, hardened them with fire, and arranged them within an iron frame on an iron board coated with resinous adhesive and paper ash.

He heated and levelled the assembled form, printed from it, then reheated it to release the characters. The reusable pieces were stored in compartments organised by rhyme.

He worked two boards alternately — one printing while the next was being composed — and kept more than twenty duplicate pieces for very common characters such as zhi and ye.

What it did not change

Shen said the method became efficient at the scale of hundreds or thousands of copies. He introduces it against an established Song book industry dominated by carved woodblocks, for which every page required a fixed block.

No specific book, customer or immediate large-scale adoption is documented, and woodblock printing remained the preferred Chinese method for centuries. Scholars have debated what clay compound was used, and whether ordinary fired clay would have had the durability and ink behaviour required.

Shen Kuo reports that after Bi Sheng died, members of Shen's own extended family obtained and preserved the type.