Movable type, is the system of printing and typography that uses movable components to reproduce the elements of a document (usually individual letters or punctuation). The first known movable type system was invented in China by Bi Sheng out of ceramic between 1041 and 1048 AD. Metal movable type was first invented in Korea during the Goryeo Dynasty (around 1230). This led to the printing of the Jikji in 1377 - today the world's oldest extant movable metal print book.
Neither movable type system was widely used, probably because of the enormous amount of labour involved in manipulating the thousands of ceramic tablets, or in the case of Korea, metal tablets, required by the use of Chinese characters.
The technique of imprinting multiple copies of symbols or glyphs with a master type punch made of hard metal first developed around 3000 BC in ancient Sumer. Bricks for buildings and bars or ingots of precious metal were imprinted with a distinctive stamped design; the act of stamping the ingots certified them as currency by the power of the authority symbolized by the type image. These metal punch types can be seen as precursors of the letter punches adapted in later millennia to printing with movable metal type. Cylinder seals were also used to "sign" documents and mark objects as the owner's property.
Type-founding as practiced in Europe and the west consists of three stages.
Punchcutting: If the glyph design includes enclosed spaces (counters), a counterpunch is made. The counter shapes are transferred in relief (cameo) onto the end of a rectangular bar of mild steel using a specialized engraving tool called a graver. The finished counterpunch is hardened by heating and quenching (tempering), or exposure to a cyanide solution (case hardening).
The counterpunch is then struck against the end of a similar rectangular steel bar—the letterpunch—to impress the counter shapes as recessed spaces (intaglio). The outer profile of the glyph is completed by scraping away with a graver the material outside the counter spaces, leaving only the stroke or lines of the glyph. Progress toward the finished design is checked by successive smoke proofs; temporal prints made from a thin coating of carbon deposited on the punch surface by a candle flame. The finished letterpunch is finally hardened to withstand the rigors of reproduction by striking.
One counterpunch and one letterpunch are produced for every letter or glyph making up a complete font.
Modern, factory-produced movable type was available in the late 19th century. It was held in the printing shop in a job case, a drawer about 2 inches high, a yard wide, and about two feet deep, with many small compartments for the various letters and ligatures. The most popular and accepted of the job case designs in America was the California Job Case, which took its name from the Pacific coast location of the foundries that made the case popular.
Regardless of who actually invented the case, in order to make his typesetting more efficient, the inventor arranged the compartments according to the letters' frequency of use. The more frequent letters (t, n, e, i, o, r) are arranged in a rough circle directly in front of the typesetter, while the less-frequently used letters and characters are further away. The arrangement of the letters in the California Job Case became so popular and commonly adopted that a skilled typesetter could "read" the text set by another typesetter, just by watching the positions of the compartments where the typesetter reached for his letters.
The California Job Case has three sections, with the rightmost sections containing capital letters in alphabetic order except for the "J" and "U", moved to the lowest line to help avoid confusing them with "I" and "V" respectively. The lower case letters and punctuation marks are in the left and center sections, with the numbers 1 to 8 at the top of the center section, while the ligatures (combined letters, such as "ff", "fi", "æ" etc.) are in various locations about the exterior.
In addition to placing the most commonly used letters in setting text in a given language in the easiest positions for the typesetter to get to, the characters' boxes varied in size depending upon the frequency of usage of the character. Thus for English the "e" box is the largest while the "j", "k", "q", "x", and "z" boxes are the smallest.
Prior to the adoption of the California Job Case, the capital letters were stored in a separate drawer or case that was located above the case that held the other letters; this is why capital letters are called "upper case" characters while the non-capitals are "lower case".
Other large compartments in the California Job Case held spacers, which are blocks of blank type used to separate words and fill out a line of type, such as em and en quads (quadrats, or spaces. A quadrat is a block of type whose face is lower than the printing letters so that it does not itself print.). An em space was the width of a capital letter "M" – as wide as it was high – while an en space referred to a space half the width of its height (usually the dimensions for a capital "N").
Individual letters are assembled into words and lines of text with the aid of a composing stick, and the whole assembly is tightly bound together to make up a page image called a forme, where all letter faces are exactly the same height to form a flat surface of type. The forme is mounted on a printing press, a thin coating of viscous ink is applied and impressions made on paper under great pressure in the press. "Sorts" is the term given to special characters not freely available in the typical type case, such as the "@" mark, etc.