Important: Safety Warning
This page describes trade processes that use dangerously toxic materials such as cyanide solutions, mercury amalgams, or strong acids. These processes require training, equipment, and precautions far beyond what the text describes.
This information has been left in for historical purposes but should not be acted upon.
Type-metal
Lead is the principal ingredient of type-metal, with varying proportions of antimony, ranging from 17 to 20 per cent of the latter, with small proportions of other metals to harden it, as tin, bismuth, nickel, and copper. Ductility, hardness, and toughness being the prime requisites of a type-metal, these alloys must vary according to the quality and nature of the work for which they are intended.
A less proportion of antimony is used for large than for small type. Small type must be harder, to resist the wear and make it rigid. In 1855 Besley's patent type-metal came into use, consisting of lead 100, antimony 30, tin 20, copper 8, bismuth 2, nickel 8.
The common type-metal compound for mixtures consists of lead 80, antimony 20, with from 5 to 6 of bismuth.
Lead 3, antimony 1 makes the hard alloy for the smallest type; if required softer, add one part more to the lead.
Medium-sized types require lead 5, antimony 1. Large types, lead 6, antimony 1; or lead 7, antimony 1 for a softer grade.
Stereotype plates, 4 to 8 of lead to 1 of antimony, according to hardness required.
About five per cent of tin may be used on the small type, or a small proportion of copper.
The antimony is very serviceable in type-founding: being a metal that expands in cooling, it counteracts the high shrinkage of the lead, and thus preserves the original size of the cast--a very important feature in stereotype-casting. SEE TYPE-FOUNDING.