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It can be said that gold was the chosen material of kings, silver satiated the wealthy, the middle class had their bronze, and pewter filled in the gaps for the rest of the simple objects, like ornaments, jewellery and dinnerware. Pewter, because of its lead and tin components, mimics the appearance of silver when freshly cast, adding to its aesthetic appeal. Pewter, in spite of its simple form and inexpensive cost, has some advantages when used in the casting process.
With a very low melting point,and because of its alloy mixture of lead and tin, pewter can be melted into a malleable liquid at around 399 degrees Celsius (for the true lead-base pewter). For casting purposes, this makes it ideal for small handmade ovens and kilns, requiring no more than a small butane torch. Pewter moulds and brick ovens have been found from the Norse culture, which required no extensive heat-producing equipment or fire-raising modification.
With the low melting point of lead and tin, fluidity is enhanced, which allows the use of open-topped moulds. The high fluid content also lets the pewter flow and reach into delicate casting areas that are thin and have sharp angles. The high fluidity of pewter makes it ideal for ornate brooches, earrings and rings.
When pewter is cast in a slate or green soapstone mould, and used with a backing plate, it can be easily poured from the edge of the mould. Using this process can produce hundreds of copies without cast deformation or mould wear. Pewter offers fast set-up, melting and cooling, which complements a mass production process for one or several objects.
Spin casting pewter involves the force of circular rotation while the cast sits in a mould. After the mould has been filled with the casting material, it is rotated to saturate all the interior channels and sides. The technique has also been called centrifugal rubber mould casting. It flushes air pockets out of the casting material, to ensure a solid, non-porous form.
Slush casting works well for certain applications with pewter. When the molten alloy is poured into a cool mould, it hardens fast and creates a shell figure or external outline. The procedure reduces the overall weight of the cast and retains the fine exterior details, but loses some definition on the inside. Slush casting works well for cupboard and door handles. Candlesticks and decorative vases benefit from the cold mould technique, in which quality and appeal do not suffer.
A lead-free, non-toxic pewter called Tin Base Fine Pewter has been produced that contains 92 per cent tin and 7.75 per cent antimony. It has only .25 per cent copper. The copper additive makes the metal more malleable or ductile, allow the use of a hammer for shaping, if necessary. The melting temperature is a very low 239 to 246 degrees Celsius.
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