Stereotyping was invented in the late 18th century as the printed book rose in popularity and the need for speed in printing and higher output increased. In printing, a stereotype uses a plaster mould, called a “flong”, made from the surface of a forme, or one side of a sheet. The mould is then used to cast a stereotype plate from hot metal. The resulting plate is more durable and stands up to the increased output of high-speed press runs. Multiple plates can also be run on multiple presses. In French, this is called cliché printing, the word “cliché” having evolved to highlight the meaning “an exact copy of the original” and “lacking in original thought”. Supposedly, the term “cliché” printing is an onomatopoeia, resulting from a sound made during the stereotype printing process.
The photographs below show stereotype printing materials found in the Edward A. Mitchell papers, a U.S. Representative from Evansville, Indiana from 1947-1949. The photographs (in order) show a flong (rose-colored plaster mould), the metal stereotype plate, and an example of the resulting print.