Tombac, or tombak, is a brass alloy with high copper content and 5–20% zinc content.[Institute of Metals, Journal of the Institute of Metals Volume 43, Institute of Metals: 1930][
Tibor Eric Robert Singer, German-English dictionary of metallurgy: with related material on ores, mining and minerals, crystallography, welding, metal-working, tools, metal products, and metal chemistry, McGraw-Hill: 1945: 298 pages]
Etymology
The term
tombak is derived from
tembaga, an Indonesian/
Malay language word of Javanese origin meaning 'copper'.
Tembaga entered Dutch usage concurrent with their colonisation of
Indonesia. Likely, the term was used generically to describe Indonesian high-copper brass items, including
gamelan . It is one of the very few Indonesian loan words used in
English language or
German language.
Common types
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Modern CuZn15 (DIN: CuZn15 ; UNS: C23000 ; BS: CW 502L (CZ 102) ; ISO: CuZn15) – tombak with a gold colour, very good for cold forming, suitable for pressing, , or embossing
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modern CuZn12 (not standardized) – same characteristics and applications as CuZn15, slightly different colour
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modern CuZn10 (DIN: CuZn10; UNS: C22000; BS: CW 501L (CZ 101); ISO: CuZn10) – similar characteristics and applications as CuZn15 and CuZn12, noticeable reddish colour
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modern white tombac – CuZn10 that is zinc content 10%, with trace arsenic
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modern enamel tombac or emailler tombak – an alloy of 95% copper and 5% zinc, suitable for enamelling, therefore the name.
Andrew Ure notes the following forms of tombak in widespread use during the time the text was published (1856):[Andrew Ure, A dictionary of arts, manufactures and mines: containing a clear exposition of their principles and practice Robert Hunt (ed.), D. Appleton & Co.: 1856: pp243]
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"Gilting tombac":
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Copper 82%, zinc 18%, lead 1.5%, tin 3%
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Copper 82%, zinc 18%, lead 3%, tin 1%
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Copper 82%, zinc 18%, lead, tin 0.2%
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"France tombac for sword handles", Hilt and fittings: copper 80%, zinc 17%, 3% tin
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"Yellow tombac of Paris" for gilt ornaments: copper 85%, zinc 15%, trace% tin
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"Hanover tombac": copper 85.3%, zinc 14.7%
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Chrysochalk: copper 86%, zinc 14%
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"Red tombac of Paris": copper 90%, zinc 7.9%, 1.5% lead
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"Red tombac of Vienna": copper 97.8%, zinc 2.2%
Piggot states the brass used for machinery and in England was composed of copper 74.5%, zinc 25%, and lead 0.5%, which would make it a tombac according to Ure.[Aaron Snowden Piggot, The chemistry and metallurgy of copper, Lindsay and Blakiston: 1858: 388 pages: pp354, google book reference: [1]]
Piggot's own definition of tombak is problematic at best: "red brass, or tombak, as it is called by some, has a great preponderance of copper, from 5 ounces of zinc down to 1/4 ounce of zinc to the pound of."
Tempers
Typical tempers are soft annealed and rolled
hardness.
Applications
Tombac is soft and easy to work by hand: hand tools can easily punch, cut,
Vitreous enamel,
repousse,
Engraving,
Gilding, or
etch it. It has a higher than most brasses or copper, and does not easily
tarnish.
Historically, it was used by the Javanese as a
faux gold finish for
objects d'art and ornaments.
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Most commonly, tombac in modern society is used in medals and of lesser importance, such as the German Oldenburg Long-Service Medallion for their Gendarmerie, and the Visit to Ireland Medal 1900 for the Irish police forces.
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The Pickelhaube and cuirass of the Imperial German and Prussian Army were at one time made of tombac.
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German, particularly Prussian, field (which were also sold to equip the White Movement), had and decorative fittings made of tombac.
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Currently, tombac foils are used in arts and crafts for decorative articles, especially as an economic alternative to very expensive gold leaf.
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Industry uses tombac foil for heating foils and etch applications.
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Gilding metal is a type of tombac which is one of the most common jacketing materials for full metal and hollow-point jacketed bullets.
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The 1980 Olympic 'Bronze' medals were actually tombac.
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During World War II, Canada minted 5-cent pieces (nickels) in tombac in 1942 and 1943.
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The German military used it for some combat medals during World War II.
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The Swedish armed forces adopted a special-service round for the Carl Gustav m/45 submachine gun with a tombac-plated steel jacket surrounding the lead core of the bullet loaded in the cartridge. While Gun barrel can cut into the tombac, the steel jacket resists deformation and thus causes the gas pressure to rise higher than the previous soft-jacketed m/39, giving the 6,8-g (106-grain) bullet a muzzle velocity of .
[Arméstabens taktiska avdelning februari 1962 : "Erfarenheterna från striderna i Kongo under september och december 1961"]
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Brass alloys, including tombak, are occasionally used in architecture, such as ornaments, roofs or outside wall plating. It withstands corrosion well.
See also
External links
