Pewter is an alloy--a material made of two or more elements. The exact composition of pewter is determined by several factors, including when and where it was made, who made it and what it was made for. The use of pewter is thought to date as far back as the Bronze Age, and its production has gone through several evolutions.
Tin is the main component of pewter. Though the amount of tin in pewter has varied since antiquity, current standards and regulations dictate that modern-made pewter be composed of at least 90 per cent tin for general use or 92 per cent when used in the manufacture of food and drink receptacles. As tin is a soft metal, it is combined with small quantities of harder metals to make it more durable.
At one time, lead was the second-most-abundant element in pewter. Some pewter consisted of up to 30 per cent lead, which was used as a hardener. The problem with using lead was that it tended to cause the pewter to tarnish and take on a black colour. Later the health hazards of lead were discovered, and pewter makers ceased using it altogether.
A small amount of copper is used in the manufacture of pewter. The amount varies from 3 per cent to about 7 per cent. Though a soft metal, copper is used as a hardening agent. It is still used in pewter production.
Antimony makes up 2 per cent to 7 per cent of pewter composition. It, like copper, is used as a hardening agent and is still widely used in pewter production.
Bismuth, like copper, lead and antimony, is used as a hardening agent. Much modern copper contains no bismuth at all.
Zinc has been used in pewter production in amounts of 1 per cent to 3 per cent. It is one of the least common elements in pewter and often is not present.
The most common elements used in modern pewter production are tin, copper and antimony. Tin makes up about 92 per cent, with copper and antimony making up the remainder.