Tombac

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Not to be confused with Tonbak.
Ottoman tombac ewer and basin set - 1870 - Collection of Turkish and Islamic Arts Museum - Brought to museum in 1926 from the tomb of Sultana Pertevniyal.

Tombac, as it is spelled in French, or Tombak, is a brass alloy with high copper content and 5-20% zinc content.[1] Tin, lead or arsenic may be added for colouration.[2][3] It is a cheap malleable alloy mainly used for medals, ornament, decoration and some munitions. In older use, the term may apply to brass alloy with a zinc content as high as 28%-35%.[1][4]

Etymology

The term tombak is derived from tembaga, an Indonesian/Malay word of Javanese origin meaning copper. Tembaga entered Dutch usage concurrent with their colonisation of Indonesia (see Dutch East Indies). Likely, the term was used generically to describe Indonesian high-copper brass items, including gamelan gongs. It is one of the very few Indonesian loan words used in English, German or Dutch.

Common Types

  • 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, hammering, embossing.

  • modern CuZn12

(not standardized) Same characteristics and applications as CuZn15; slightly different colour.

  • modern CuZn10

(DIN: CuZn10 ; UNS: C22000 ; BS: CW 501L (CZ 101) ; ISO: CuZn10) Similar characteristics and applications as CuZn15 und CuZn12; noticeable reddish colour.

  • modern White Tombak

CuZn10- that is Zinc content 10%, with trace arsenic

  • modern Enamel Tombak or Emailler Tombak

An alloy of 95% copper and 5% zinc is very suitable for enamelling, therefore the name.
Ure notes the following forms of Tombak in widespread use during the time the text was published (1856):[5]

    • "Gilting Tombak":
      • Copper 82%, Zinc 18%, Lead 1.5%, Tin 3%
      • Copper 82%, Zinc 18%, Lead 3%, Tin 1%
      • Copper 82%, Zinc 18%, Lead, Tin 0.2%

Copper 80%, Zinc 17%, 3% Tin

    • "Yellow Tombak of Paris" for gilt ornaments:

Copper 85%, Zinc 15%, trace% Tin

Copper 85.3%, Zinc 14.7%

    • Chrysochalk

Copper 86%, Zinc 14%

Copper 90%, Zinc 7.9%, 1.5% Lead

Copper 97.8%, Zinc 2.2%
Piggot states the brass used for machinery and locomotives in England was composed of Copper 74.5%, Zinc 25%and Lead 0.5%- which would make it a tombak according to Ure.[6] 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 1/2 ounce of zinc to the pound [sic: copper?]"[6]

Tempers

Typical tempers are soft annealed and rolled hard.

Applications

A "bronze" medal (actually tombac) from the 1980 Summer Olympics

Tombak is easy and soft to work by hand: hand tools can easily punch, cut, enamel, repousse, engrave, gilt or etch it. It has a higher sheen 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.

  • most commonly Tombak in modern society is used in medals and awards of lesser importance, such as the Dutch Oldensburge Long-Service Medallion for their Gendarmerie (Oldenburgse Onderscheiding voor Langdurige Dienst in de Gendarmerie).
  • the Pickelhaube and cuirass of the Imperial German and Prussian Army were at one time made of tombak
  • German, particularly Prussian field uniforms (which were also sold to equip the White Russians), had buttons and decorative fittings made of tombak.
  • currently tombak foils used in art and craft for decorative articles, especially as an economic alternative to very expensive gold leaf.
  • Industry uses tombak foil for heating foils and etch applications.
  • gilding metal is a type of tombak which is one of the most common jacketing materials for full metal jacket and jacketed hollow point bullets.
  • The 1980 Olympic 'Bronze' Medals were actually Tombak
  • During World War II Canada minted nickels in tombac in 1942 and 1943.
  • German military use for some combat medals, during World War II.

See also

References

  1. ↑ 1.0 1.1 http://www.market-metal.com/reviews/reviews_175
  2. ↑ Institute of Metals, Journal of the Institute of Metals Volume 43, Institute of Metals: 1930
  3. ↑ http://www.schlenk.de/index.php?id=519&L=1&kat=1.1.1#719
  4. ↑ 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
  5. ↑ 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
  6. ↑ 6.0 6.1 Aaron Snowden Piggot, The chemistry and metallurgy of copper, Lindsay and Blakiston: 1858: 388 pages: pp354, google book reference:

External links

Look up tombac in Wiktionary, the free dictionary.

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