The phrase hot type (sometimes hot metal or hot lead) refers to a printing technology developed late in the 19th century in which molten lead is injected into a mold to cast metal type.
Machines like the Linotype were used to generate a full line of text at a time using brass letter molds (or matrices). When each line of words is complete, molten lead is forced against it, creating a line of type known as a slug. Slugs are assembled in a metal frame the size of a full page and readied for printing. After printing, slugs are pitched into a “hell box,” melted and poured into molds to make new ingots.
The lead ingots used by Linotypes weigh roughly 22 pounds each and are commonly referred to as “pigs.” The ingot is suspended by a hook and chain over a melting pot. As the level in the pot drops, the pig is gradually lowered into the pot, maintaining a constant level of molten metal. A counterweight serves as a signal to the operator that another ingot is needed.
Beginning in the 1960s, hot type began to give way to cold type, which is technically neither cold nor type, but rather phototypesetting. Machines generate text printed on photographic paper. Every piece of text is then run through a machine that applies hot wax to one side (wax allows items to be repositioned multiple times), hand-trimmed and positioned on a page-size template.
Once a page layout is complete, a film negative of the page is created. That negative is used to expose the image of the page onto an aluminum plate, and the plates are applied to a printing cylinder on the press. FC