Chemistry:Tombac

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Tombac, or tombak, is a brass alloy with high copper content and 5–20% zinc content. Tin, lead or arsenic may be added for colouration.[1] [failed verification]</ref>{{dead link|date=May 2026} It is a cheap malleable alloy mainly used for medals, ornament, decoration and some munitions. The term may apply to brass alloy with higher zinc content.[2]{{failed verification|date=May 2026} !--A commercial metal sales site, and not a reliable source for this type of academic mettalurgical information:[3]-->

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. 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 or German.

Common types

Andrew Ure, writing in the late 19th century, and summarising with regard to "Tomba[c], or red brass", states that "in the cast state, [it] is an alloy of copper and zinc, containing not more than 20 per cent of the latter constituent."[4]: p. 243  He notes that the specific gravity of brass, in general, is "greater than the mean density of its constituents, varying from 7.82 to 8.73, according to the proportion of zinc and copper".[4]: pp. 243f  He goes on to note, with regard to tombac in particular—which he uniformly spells as "tombak" (as will thus appear in his quotations)—that its specific gravities are yet higher, with "sheet tombak (81.25 copper + 18.75 zinc) [being] 8.788" and that "tombak wire (87.5 copper + 12.5 zinc) has been found so great as 9.00".[4]: p. 244 

On publishing his A dictionary of the Arts, Manufactures, and Mines in England in 1839, and republishing in the U.S. 1856, Ure noted that,

"Red brass, the Tombak of some... consists of more copper and less zinc, than go to the composition of [yellow] brass [at 70 copper, 30 zinc[4]: p. 243 ]; [Tombak] being from 2½ to 8 or 10 of the former [copper] to 1 of the latter [zinc]. At the famous brass works of Hegermühl... 11 parts of copper are allowed with 2 of zinc into red brass, from which plates are made that are afterward rolled into sheets. From such an alloy the Dutch foil, as it is called, is manufactured at Nürnberg; Pinchbeek, Similor, Mannheim gold, are merely different names of alloy similar to Prince's metal. The last consists of 3 of copper and 1 of zinc, separately melted, and suddenly incorporated by stirring.[5]: p. 165 [4]: p. 239 

A.S. Piggot, writing in 1858, offered a distinct definition of tombac (likewise using the varian "k" spelling), and perhaps drawing from Ure, stated that:

Red brass, or tombak, as it is called by some, has a great preponderance of copper, from 5 ounces of zinc down to ¼ ounce of zinc to the pound [of copper]. At Hegermühl, 11 parts of copper are alloyed with 2 of zinc to make a red brass, which is afterward rolled into sheets. At Nürnberg, Dutch foil is made from a similar alloy.[6]: p. 355 

Piggot also states separately that the brass used for machinery and locomotives in England was composed of copper 74.5%, zinc 25%, and lead 0.5%,[6]: p. 354  a combination that would make it a tombac according to Ure.[citation needed][original research?]

Other tombac compositions that Ure reports are:[4]: p. 243 

  • "tombak for making gilt articles"—
    • Copper 82.0%, zinc 18.0%, lead 1.5%, tin 3.%;
    • Copper 82%, zinc 18%, lead 3%, tin 1%; and
    • Copper 82.3%, zinc 17.5%, tin 0.2%.[4]: p. 243  And
  • "French tombak for sword handles, &c.": copper 80%, zinc 17%, tin 3%;
  • "tombak of the Okar, near Goslar, in the Hartz": copper 80%, zinc 17%, tin 3%;
  • "yellow tombak of Paris for gilt ornaments": copper 85%, zinc 15%, tin a trace percentage;
  • "tombak for [gilt ornaments] from... Hanover": copper 85.3%, zinc 14.7%;
  • a tombak he refers to as "chrysochalk": copper 86%, zinc 14%;[4]: p. 243 [7]
  • "Red tombac from Paris": copper 90.0%, zinc 7.9%, 1.6% lead; and
  • "Red tombac of Vienna": copper 97.8%, zinc 2.2%.[4]: p. 243 


Other alloy formulations include:[according to whom?]


Ure goes on to report a further composition, with proportions given in the "parts" of each metal—

  • "Prince's metal": 3 parts copper and 1 part zinc.[4]: p. 243 

He then goes on to report further compositions, in "parts", starting from copper and "yellow brass" (the "mean proportion... [of that being] 30 zinc to 70 copper"[4]: p. 243 ), rather than presenting fundamental constituents—

  • "Pinchbeck": "2 parts copper and 1 yellow brass";[4]: p. 243 [8] and
  • "Mannheim gold (semilor)": 2.8 parts copper, 1.2 parts yellow brass, 0.3 parts tin.[4]: p. 243 [9][10]

Ure goes on to note that the alloy from which a form of "white metal buttons" are cast is composed of 3.2 parts yellow brass, 0.4 parts zinc, 0.2 parts tin.[4]: p. 243 [11][12][13]


With regard to modern forms, compositions include:[according to whom?]

Tempers

Typical tempers are soft annealed and rolled hard.[citation needed]

Applications

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


Tombac is soft and easy to work by hand: hand tools can easily punch, cut, enamel, repousse, engrave, gild, 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, tombac in modern society is used in medals and awards 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.[14]
  • The Pickelhaube and cuirass of the Imperial German and Prussian Army were at one time made of tombac.
  • German, particularly Prussian, field uniforms (which were also sold to equip the White Russians), had buttons and decorative fittings made of tombac.
  • Currently, tombac foils are used in arts and crafts for decorative articles, especially as an economic alternative to very expensive gold leaf.
  • Industry uses tombac foil for heating foils and etch applications.
  • Gilding metal is a type of tombac which is one of the most common jacketing materials for full metal and hollow-point jacketed bullets.
  • The 1980 Olympic 'Bronze' medals were actually tombac.
  • During World War II, the Royal Canadian Mint produced 5-cent pieces (nickels) in tombac in 1942 and 1943.
  • The German military used it for some combat medals during World War II.
  • 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 the lands of the 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-gram (105 gr) bullet a muzzle velocity of 420 m/s (1,378 ft/s).[15]
  • Brass alloys, including tombak, are occasionally used in architecture, such as ornaments, roofs or outside wall plating. It withstands corrosion well.[16]

See also

  • Chemistry:Tumbaga – Non-specific alloy of gold and copper used in pre-Columbian Mesoamerica

References

  1. ↑ Unstated. (1930). "Unstated title.". Journal of the Institute of Metals 43: Unstated issue, pg. nos.. 
  2. ↑ Singer, T.E.R. (1945). "Unspecified entry.". German-English Dictionary of Metallurgy: With Related Material on Ores, Mining and Minerals, Crystallography, Welding, Metal-working, Tools, Metal Products, and Metal Chemistry. New York, NY: McGraw-Hill. p. unstated.. https://books.google.com/books?id=_VSFAAAAIAAJ. Retrieved 2026-05-13.  Note, no book content is available at this web link.
  3. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named market-metal.com
  4. ↑ 4.00 4.01 4.02 4.03 4.04 4.05 4.06 4.07 4.08 4.09 4.10 4.11 4.12 4.13 Ure, Andrew (1856). Hunt, Robert. ed. A Dictionary of Arts, Manufactures, and Mines: Containing a Clear Exposition of Their Principles and Practice. I. New York, NY: D. Appleton & Co.. pp. 47, 239, 243f. https://archive.org/details/dictionaryofart01urea/page/239/mode/1up?q=tombak. Retrieved 2026-05-13. 
  5. ↑ Ure, Andrew (1839). A Dictionary of Arts, Manufactures, and Mines: Containing a Clear Exposition of Their Principles and Practice (first, illustrated ed.). London, England: Longman, Orme, Brown, Greene, & Longmans. pp. 30, 165, 1258. http://archive.org/details/b2930345x. Retrieved 2026-05-13. 
  6. ↑ 6.0 6.1 Piggot, Aaron Snowden (1858). The Chemistry and Metallurgy of Copper (illustrated ed.). Philadelphia, PA: Lindsay and Blakiston. p. 354f. ISBN 9780608406817. https://books.google.com/books?newbks=0&id=XnIQAAAAIAAJ&q=tombak#v=snippet&q=tombak&f=false. Retrieved 2026-05-13. "[Subtitle] Including a Description of the Principal Copper Mines of the United States and Other Countries, the Art of Mining and Preparing Ores for Market, and the Various Processes of Copper Smelting, &c." 
  7. ↑ Erhard Brepohl purportedly lists the composition of chrysochalk, which he refers to as "Alkeizatlee", as being: copper 66.4%, zinc 16.6%, lead 5.7%, tin 10%, magnesium 1.3%, see Brepohl, Erhard (1982) (in ru). Теория и практика ювелирного дела. Leipzig, Germany: Veb. Fachbuchverlag. https://djvu.online/file/JWrBoH0g0FwEz. Retrieved 2026-05-13.  Note, this citation is an amalgam of the original German edition, the source of the Russian translation, and the translated volume (both incomplete). The publisher's information is from the German source edition, the web link is to the Russian translation (the details of which have yet to be extracted).
  8. ↑ By observation, this Pinchbeck is 2 parts copper, and, from the yellow brass, 0.7 parts copper and 0.3 parts zinc, or, in toto, 2.7 parts copper and 0.3 parts zinc (i.e., 9 parts copper and 1 part zinc).
  9. ↑ Each numeric component of this Ure formulation is presented here, divided by 10, to make its comparison to Pinchbeck the easier.
  10. ↑ By observation, this Mannheim gold is 2.8 parts copper, and, from the yellow brass, (0.7 x 1.2) parts copper and (0.3 x 1.2) parts zinc; simplifying and including the tin, this is (2.80 + 0.84) parts copper, 0.36 parts zinc, 0.3 parts tin. Summing and simplifying, this is, in toto, 3.64 parts copper, 0.36 parts zinc, and 0.3 parts tin (i.e., 10.11 parts copper, 1.00 parts zinc, and 0.83 parts tin).
  11. ↑ See the notes that follow, and the described composition of Prince's metal, above.
  12. ↑ Each numeric component of this Ure formulation are again presented here, divided by 10, for consistency.
  13. ↑ By observation, this cast button alloy is, from the yellow brass and zinc, (3.2 x 0.7) parts copper, and (3.2 x 0.3) plus 0.4 parts zinc, plus its 0.2 parts tin, or, simplifying, 2.24 parts copper, (0.36 + 0.4) parts zinc, 0.2 parts tin. Summing, this is, in toto, 2.24 parts copper, 0.76 parts zinc, and 0.2 parts tin (i.e., 2.95 parts copper, 1.00 parts zinc, and 0.26 parts tin).
  14. ↑ Craig, John Herbert McCutcheon (1953). The Mint; a history of the London Mint from A.D. 287 to 1948. Cambridge University Press. p. 325. https://archive.org/details/minthistoryoflon0000crai/page/325/mode/1up. 
  15. ↑ Arméstabens taktiska avdelning februari 1962 : "Erfarenheterna från striderna i Kongo under september och december 1961"
  16. ↑ "Brass Sheet Metal Dealer on the Alloy's Use in Architectural Projects". Rotax Metals. 31 July 2014. https://www.rotaxmetals.net/brass-sheet-metal-dealer-on-the-alloys-use-in-architectural-projects/. Retrieved 14 July 2019. 

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