Tombac
Also: Red brass
Tombac is a copper-zinc alloy containing between 67% and 90% copper; its gold-like colour has long made it a favourite decorative material and a traditional coin metal.
Tombac (a word derived from the Malay tembaga, meaning copper) is a lustrous, gold-toned copper-zinc alloy whose copper share sits somewhere between 67% and 90% by weight. The more copper it contains, the redder and more gold-like the finished metal appears - which is precisely why craftsmen have reached for tombac as an affordable stand-in for gold for centuries.
Composition and grades
| Name | Copper | Zinc | Colour |
|---|---|---|---|
| Red tombac | 85-90% | 10-15% | coppery gold |
| Yellow tombac | 72-80% | 20-28% | brassy gold |
| White tombac (Prince's metal) | 67-72% | 28-33% | pale gold |
Small additions of lead, arsenic or tin may be used to fine-tune workability, but they do nothing to change the essential fact that tombac is a base metal with no precious metal value whatsoever.
Where tombac is used
Tombac turns up wherever a gold-like appearance is wanted without a gold-like price tag:
- Coins and medals: Countless circulating coins, orders and decorations are struck from tombac, sometimes with a thin coat of gold on top (gold plating). Modern bimetallic coins frequently use tombac for the core or the outer ring.
- Jewellery and ornaments: In costume jewellery and decorative fittings, tombac mimics the look of yellow gold convincingly.
- Engineering: Thanks to its excellent cold-forming behaviour and corrosion resistance, tombac is found in cartridge cases, watch cases and plumbing fixtures.
Tombac and precious metal valuation
Because tombac contains no precious metal at all, it is only relevant to the melt value calculator through the prevailing copper price. Objects made of tombac - even gilded ones - have no intrinsic gold value; what matters is solely the material worth of the copper and zinc they contain.
Tombac material value ~ weight (g) x copper share x copper price (EUR/g)
Gilded tombac pieces are normally traded as base metal at the point of sale, provided the gold layer is thinner than roughly 0.5 microns - at that thickness the amount of gold is negligible.
Telling tombac apart from similar alloys
- Nickel silver: copper-zinc-nickel, silvery in colour - contains no silver.
- Red gold: a genuine gold-copper alloy with a defined fineness (for example 750/1000 Au).
- Gold filled / gold double: a mechanically bonded gold layer over a base metal - far more gold than mere plating.
In a nutshell
Tombac is a high-quality imitation of gold with no precious metal content at all - visually persuasive, yet worth only as much as the copper inside it. Anyone valuing a tombac object should look to the current copper price, not to the gold market.