Stereotyping << STEHR ee uh typ ihng >> is the method of making metal plates for use in printing. In the process, workers set the type and lock it into a steel chase (frame). Others brush the face of the type with a thin coating of oil. A sheet of thick, composite paper, called flong, is laid on the type and beaten or pressed tightly against it. This sheet takes an impression of the face of the type or cut (picture) in the frame. The paper mold thus formed then goes into an oven and bakes until it becomes hard and dry. This mold, which is known as a matrix, or mat, is placed in a box face up. A worker pours melted stereotype metal, made up of tin, antimony, and lead, over the mold. The metal hardens at once, forming a solid plate, and the page is printed from this plate.
Introduction of the stereotype process helped speed up newspaper printing. The stereotype plates used on small presses were flat. Those used on rotary presses for newspapers were in the form of half cylinders. It took only about 15 minutes to make stereotype plates, and they were inexpensive compared to other printing plates. One matrix could produce a number of plates. Today, stereotyping has been replaced by offset lithography for most general printing in the United States (see Printing (Offset lithography) ). But it is still used in less developed countries.
