Chemistry:Gilding metal
Gilding metal is a form of brass (an alloy of copper and zinc) with a much higher copper content than zinc content. Exact figures range from 95% copper and 5% zinc[1] to “8 parts copper to 1 of zinc” (11% zinc) in British Army Dress Regulations.[2]
Gilding metal is used for various purposes, including the jackets of bullets, driving bands on some artillery shells,[3] as well as enameled badges and other jewellery. The sheet is widely used for craft metalworking by hammer working.[1] It is also used particularly as a lower-cost training material for silversmiths. Starting in 1944, shell casings made of gilding metal were melted down by the United States Mint to be made into pennies.[4] These pennies replaced the less popular steel cent of 1943, and the pennies of this composition were produced until 1946.
Gilding metal was also used for the "bronze" Olympic medal at the 2020 Summer Olympics held in Tokyo, Japan in 2021.[5]
Gilding metal may be annealed by heating to between 800–1,450 °F (427–788 °C).[6] It should be cooled slowly afterwards, to reduce risk of cracking.[7]
See also
- Pinchbeck alloy
References
- ↑ 1.0 1.1 Untracht, Oppi (1968). Metal Techniques for Craftsmen. p. 18. ISBN 0-7091-0723-4.
- ↑ War Office (1904) Dress Regulations for the Officers of the Army (Including the Militia). London: HMSO. p. 4
- ↑ "105mm Advanced Cannon Artillery Ammunition Program (ACA2P) § 155mm M107". http://www.gd-ots.com/sitepages/artillery.html.
- ↑ "1943 Steel Cent | Lincoln Steel Penny" (in en-US). https://lincolncents.net/1943-lincoln-steel-cent/.
- ↑ "How much are Olympic medals worth?" (in en-US). https://www.cnn.com/2021/07/31/sport/olympic-medals-value-explainer-scli-intl/index.html.
- ↑ Untracht, p. 49–50
- ↑ Untracht, p. 246
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