Type metal

In printing, type metal (sometimes called hot metal) refers to the metal alloys used in traditional typefounding and hot metal typesetting. Historically, type metal was an alloy of lead, tin and antimony in different proportions depending on the application, be it individual character mechanical casting for hand setting, mechanical line casting or individual character mechanical typesetting and stereo plate casting. The proportions used are in the range: lead 50‒86%, antimony 11‒30% and tin 3‒20%. Antimony and tin are added to lead for durability while reducing the difference between the coefficients of expansion of the matrix and the alloy. Apart from durability, the general requirements for type-metal are that it should produce a true and sharp cast, and retain correct dimensions and form after cooling down. It should also be easy to cast, at reasonable low melting temperature, iron should not dissolve in the molten metal, and mould and nozzles should stay clean and easy to maintain. Today, Monotype machines can utilize a wide range of different alloys. Mechanical linecasting equipment use alloys that are close to eutectic.The Metal Founders make Printing Letters of, is Lead hardned with Iron: Thus they chuse stub-Nails for the best Iron to Melt, as well because they are asured stub-Nails are made of good soft and tough Iron, as because (they being in small pieces of Iron) will Melt the sooner. To make the Iron Run, they mingle an equal weight of Antimony (beaten in an Iron-Morter into small pieces) and stub-Nails together. And preparing so many Earthen forty or fifty pounds Melting-pots (made for that purpose to endure the Fire) as they intend to use: They Charge these Pots with the mingeld Iron and Antimony as full as they will hold. In printing, type metal (sometimes called hot metal) refers to the metal alloys used in traditional typefounding and hot metal typesetting. Historically, type metal was an alloy of lead, tin and antimony in different proportions depending on the application, be it individual character mechanical casting for hand setting, mechanical line casting or individual character mechanical typesetting and stereo plate casting. The proportions used are in the range: lead 50‒86%, antimony 11‒30% and tin 3‒20%. Antimony and tin are added to lead for durability while reducing the difference between the coefficients of expansion of the matrix and the alloy. Apart from durability, the general requirements for type-metal are that it should produce a true and sharp cast, and retain correct dimensions and form after cooling down. It should also be easy to cast, at reasonable low melting temperature, iron should not dissolve in the molten metal, and mould and nozzles should stay clean and easy to maintain. Today, Monotype machines can utilize a wide range of different alloys. Mechanical linecasting equipment use alloys that are close to eutectic. Although the knowledge of casting soft metals in moulds was well established before Johannes Gutenberg's time, his discovery of an alloy that was hard, durable, and would take a clear impression from the mould (because it did not shrink as much as lead alone when cooled) represents a fundamental aspect of his solution to the problem of printing with movable type. (His other contributions were the creation of inks that would adhere to metal type and a method of softening handmade printing paper so that it would take the impression well.)