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. History Ceramic movable type Bi Sheng () (990–1051) developed the first known movable-type system for printing in China around 1040 AD during the Northern Song dynasty, using ceramic materials. As described by the Chinese scholar Shen Kuo (沈括) (1031–1095): In 1193, Zhou Bida, an officer of the Southern Song dynasty, made a set of clay movable-type method according to the method described by Shen Kuo in his Dream Pool Essays, and printed his book Notes of The Jade Hall (). The ceramic movable type was also mentioned by Kublai Khan's counsellor Yao Shu, who convinced his pupil Yang Gu to print language primers using this method. The claim that Bi Sheng's clay types were "fragile" and "not practical for large-scale printing" and "short lived" was refuted by later experiments. Bao Shicheng (1775–1885) wrote that baked clay moveable type was "as hard and tough as horn"; experiments show that clay type, after being baked in an oven, becomes hard and difficult to break, such that it remains intact after being dropped from a height of two metres onto a marble floor. The length of clay movable types in China was 1 to 2 centimetres, not 2mm, thus hard as horn. But similar to metal type, ceramic type did not hold the water-based Chinese calligraphic ink well, and had an added disadvantage of uneven matching of the type which could sometimes result from the uneven changes in size of the type during the baking process. There has been an ongoing debate regarding the success of ceramic printing technology as there have been no printed materials found with ceramic movable types. However, it is historically recorded to have been used as late as 1844 in China from the Song dynasty through the Qing dynasty. Movable type was invented during the Northern Song dynasty around the year 1041 by the commoner Bi Sheng. Bi Sheng's movable type was fired in porcelain. After his death, the ceramic movable-type passed onto his descendants. The next mention of movable type occurred in 1193 when a Southern Song chief counsellor, Zhou Bida (周必大), attributed the movable-type method of printing to Shen Kuo. However Shen Kuo did not invent the movable type but credited it to Bi Sheng in his Dream Pool Essays. Wooden