Typemetal

Typemetal, also known as hot metal or type metal, is an alloy of metals used in traditional hot metal typesetting. It is typically composed of lead, tin, and antimony, with lead forming the largest proportion. The precise composition varies depending on the specific application and the desired properties of the metal, such as its melting point, hardness, and flow characteristics.

The primary purpose of typemetal is to create durable and dimensionally stable type pieces, such as individual letters, numbers, and punctuation marks, or entire lines of text cast in a single slug. Lead provides a low melting point, making it easy to melt and cast. Antimony increases the hardness of the alloy and expands upon cooling, ensuring that the cast type fills the mold precisely, producing sharp and clear impressions. Tin contributes to fluidity during casting and improves the durability of the type.

Typemetal alloys are melted in heated pots and then poured into molds, either for individual type characters (foundry type) or for lines of text (in the case of slug casting machines like Linotype and Monotype). Once cooled, the solid metal type is arranged to form the desired text and used to ink and print onto paper. After printing, the typemetal could be melted down and reused, making it an economical and sustainable printing process for its time. While largely superseded by phototypesetting and digital printing, typemetal remains a significant part of printing history and is still practiced by enthusiasts and for specialized applications.