Tuesday, 28 December 2010

sandcasting with pewter

WHAT IS PEWTER?
Pewter is a malleable metal alloy, traditionally 85-99% tin, with the remainder consisting of copper, antimony, bismuth and lead. Copper and antimony act as hardeners while lead is common in the lower grades of pewter, which have a bluish tint. It has a low melting point, around 170–230 °C, depending on the exact mixture of metals. The word pewter is probably a variation of the word spelter, a colloquial name for zinc. Pewter was first used around the beginning of the Bronze Age in the Near East. The earliest piece of pewter found is from an Egyptian tomb from 1450 BC.

A typical European casting alloy contained 94% tin, 1% copper, and 5% antimony. A European pewter sheet would contain 92% tin, 2% copper, and 6% antimony. Asian pewter, produced mostly in Malaysia, Singapore, and Thailand, contains a higher percentage of tin, usually 97.5% tin, 1% copper, and 1.5% antimony. This makes the alloy slightly softer.

WHAT DOES PEWTER GET CAST INTO?

Pewter is an alloy of tin that has been gracing homes for more than 3500 years. The Egyptian civilisation, the Roman Empire and mediaeval Europe all appreciated its qualities. Today's pewter maintains its soft shine and represents an environmentally sound metal that is wholly appropriate for the use of contemporary artists.

Modern British pewter is an alloy of tin (92%), antimony (6%) and copper (2%), sometimes referred to as Britannia Metal. Because it is lead-free, it keeps its bright shine and is non-toxic. Some old pewter develops a grey patina and has a metallic smell due to its lead content. In the 14th Century, because pewter could be worked so easily, it largely replaced wood, pottery, stone and leather as the main material for the making of domestic items. Furthermore, worn out pewter items could be recycled.

The Worshipful Company of Pewterers was set up to control the quality of pewter and the trade became of great economic importance. This situation lasted until the start of the 19th Century when fine china, glass and stainless steel became available in large quantities. Craftsmen today use techniques such as casting, spinning, hammering and chasing to produce a range of decorative products for use in the home or the office, often to celebrate important events.

About Sandcasting

Sand casting is used to make large parts (typically Iron, but also Bronze, Brass, Aluminum). Molten metal is poured into a mold cavity formed out of sand (natural or synthetic).

Petrobond sand
This is fine sand that has been mulled with an oil based binding agent called Petrobond. Because it has no water, there is no steam- and while some gases are liberated from the oil, I haven't found venting to be necessary. The sand has a somewhat oily texture and smells bad after it has been burnt by the molten metal- but it works well and eliminates some trickiness from the casting process. The sand closest to the molten metal will be burnt to black dry sand after casting. This used sand can be blended back into the mix or can be scraped away (as best as you are able) and discarded. Unburnt sand can be used again

Sandcasting instructional video


Artists who use sandcasting with pewter

Michael Ricker - USA
http://www.ricker.com/index.cfm?fuseaction=category.display&category_id=201







Partners In Pewter - UK
http://www.partnersinpewter.co.uk/gallery/?p=5&a=mag&cat_id=1




Ramshorn Studio - USA
http://www.ramshornstudio.com/retail/index1.html



Richard Neal - UK
http://www.lifesculptures.co.uk/index.asp



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