Hot metal typesetting

In printing and typography, hot metal typesetting (also called mechanical typesetting, hot lead typesetting, hot metal, and hot type) refers to technologies for typesetting text in letterpress printing. This method injects molten type metal into a mold that has the shape of one or more glyphs. The resulting sorts and slugs are later used to press ink onto paper.

Two different approaches to mechanising typesetting were independently developed in the late 19th century. One, known as the Monotype composition caster system, produced texts with the aid of perforated paper-ribbons, all characters are cast separate. These machines could produce texts also in "large-composition" up to 24 point.

The Super-caster, another machine produced by Monotype, was similar in function to the Thompson, Bath, pivotal and others casters but designed to produce single type (including even larger sizes) for hand setting.

The other approach was to cast complete lines as one slug, usually comprising a whole line of text.

Of this system there have been at least 5 different enterprises:

The Linotype and similar Intertype machines came out with paper tape and electronic automation near the end of their life cycles that allowed for the news wire services to send breaking news to remote newspaper offices for prompt setting into late editions

All these machines were operated by non-qwerty-keyboards. There was however another system, where the matrices for each line were assembled in a stick by hand:

This machine was able to cast display body sizes that other mechanical composition systems were unable to produce. In this way headings could be produced to complement text produced on other machines. It also used the same alloy as Linotype machines, so was a useful adjunct to page makeup for newspapers as, when complete, all the metal could be remelted without having to be separated or the type from the headings redistributed back into case.

The success of these machines lay in different fields: the Monotype caster was more popular for bookwork that required the ability to make manual corrections and edits while the slug casting systems found success in newspaper production where speed of production and make ready for print was essential.

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