casting
PEWTER

Help I'm an American!

What is Pewter?

Throughout it's long history pewter has had an almost infinite variety of compositions, even today there are still numerous varieties produced. Through time the only common factor is a relatively high tin content which is hardened by additions of other elements. The main properties of tin that are exploited by pewter are the low melting point, good casting properties and appearance, pure tin is too soft to be of use. Many European languages make no distinction between pewter and tin for example in French étain is the same word for both. This may appear strange and certainly makes for some interesting conversations, it's a bit like having the same word for bronze and copper, but equally given the large range of compositions and the factor that tin is the main ingredient you can see the logic. Pewter's low melting point has always made it ideal for working with minimal equipment, ideal for the small workshop and great for creativity. If it all goes wrong its very easy to melt it down and start again.

Today newly manufactured pewter should be a lead free alloy usually being hardened with additions of antimony and copper, containing over 90% tin. Other elements such as silver and bismuth are sometimes used. In the past pewter often contained lead but as awareness has grown into the harmful effects of lead it should now have been eliminated. Modern pewter can be polished to a bright silver like finish or if preferred chemical darkeners can be used to simulate the patinas associated with old pewter. We manufacture a number of pewter compositions suitable for a variety of types of casting and objects. Most of the pewter we supply is destined to be cast into vulcanised rubber moulds which are spun so that centrifugal force helps to fill the mould cavity and eject any air. We supply a variety of compositions for this type of casting which are selected to suit the type of items being cast.

The Main Constituents of Modern Lead Free Pewter

Tin: Sn
The major constituent of all pewters. Pure tin is soft which is why it needs to be mixed with other metals. Usually contains between 90 and 98%

Antimony: Sb
Improves the casting qualities and has a considerable hardening effect. Modern pewters generally contain between 0.5 and 8 %

Copper: Cu
Like antimony copper improves the casting qualities has a slight hardening effect and helps retain the antimony in the molten pewter, often present between 0.25 and 2.5%
Pewter is made by melting the tin in a cast iron melting pot, the calculated weight (percentages are by weight) of copper is added to the molten tin, being heavier it sinks into the melt. Copper dissolves in molten tin at relatively low temperatures once dissolved the antimony is added again this dissolves easily without the melt going much above 400C. After cooling and thorough stirring the metal is poured into ingot moulds. Sheet pewter is made by casting billets which are scalped off then progressively reduced in thickness by passing through rollers.

Pewter sheet is a versatile material that can be used to construct all manner items such as hip flasks and tankards, pewter sheet can also be spun to make wonderful hollow ware designs. There is some snobbery between the traditional hand cast items and what is regarded as possibly a lower quality item constructed from sheet but what really matters is the final product rather than how it has been made. Although we don't manufacture pewter sheet we do produce lead free solders suitable for jointing pewter sheet in applications involving food and drink.

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Mould making : Pewter Casting Service


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