Brass Composition, Properties, and Comparison With Bronze

brass container
Brass is a common metal alloy made primarily of copper and zinc, often with lead. Qing Zhou / EyeEm / Getty Images

Brass is an alloy made primarily of copper and zinc. The proportions of the copper and zinc are varied to yield many different kinds of brass. Basic modern brass is 67% copper and 33% zinc. However, the amount of copper may range from 55% to 95% by weight, with the amount of zinc varying from 5% to 40%.

Lead commonly is added to brass at a concentration of around 2%. The lead addition improves the machinability of brass.

However, significant lead leaching often occurs, even in brass that contains a relatively low overall concentration of lead.

Uses of brass include musical instruments, firearm cartridge casing, radiators, architectural trim, pipes and tubing, screws, and decorative items.

Brass Properties

  • Brass often has a bright gold appearance, however, it can also be reddish-gold in color or silvery-white. A higher percentage of copper yields a rosy tone, while more zinc makes the alloy appear silver.
  • Brass has a higher malleability than either bronze or zinc.
  • Brass has desirable acoustic properties appropriate for use in musical instruments.
  • The metal exhibits low friction.
  • Brass is a soft metal that may be used in cases when a low chance of sparking is necessary.
  • The alloy has a relatively low melting point.
  • It's a good conductor of heat.
  • Brass resists corrosion, including galvanic corrosion from salt water.
  • Brass is easy to cast.
  • Brass is not ferromagnetic. Among other things, this makes it easier to separate from other metals for recycling.

Brass vs. Bronze

Brass and bronze may appear similar, yet they are two distinct alloys. Here's a comparison between them:

CompositionAlloy of copper and zinc. Commonly contains lead. May include iron, manganese, aluminum, silicon, or other elements.Alloy of copper, usually with tin, but sometimes other elements, including manganese, phosphorus, silicon, and aluminum.
ColorGolden yellow, reddish gold, or silver.Usually reddish brown and not as bright as brass.
PropertiesMore malleable than copper or zinc. Not as hard as steel. Corrosion resistant. Exposure to ammonia may produce stress cracking. Low melting point.Better conductor of heat and electricity than many steels. Corrosion resistant. Brittle, hard, resists fatigue. Usually a slightly higher melting point than brass.
UsesMusical instruments, plumbing, decoration, low-friction applications (e.g., valves, locks), tools and fittings used around explosives.Bronze sculpture, bells and cymbals, mirrors and reflectors, ship fittings, submerged parts, springs, electrical connectors.
HistoryBrass dates back to around 500 B.C.E.Bronze is an older alloy, dating back to about 3500 B.C.E. 

Identifying Brass Composition by Name

Common names for brass alloys may be misleading, so the Unified Numbering System for metals and alloys is the best way to know the composition of the metal and predict its applications. The letter C indicates brass is a copper alloy. The letter is followed by five digits. Wrought brasses, which are suitable for mechanical forming, begin with 1 through 7. Cast brasses, which may be formed from molded molten metal, are indicated using an 8 or 9.