Brass

"Arsenical brass" redirects here. Not to be confused with arsenical bronze or arsenical copper.
For other uses, see Brass (disambiguation).

Islamic Golden Age brass astrolabe
Brass lectern with an eagle. Attributed to Aert van Tricht, Limburg (Netherlands), c. 1500.

Brass is an alloy of copper and zinc, in proportions which can be varied to achieve different colours and mechanical, electrical, acoustic and chemical properties,[1] but copper typically has the larger proportion, generally 66% copper and 34% zinc. In use since prehistoric times, it is a substitutional alloy: atoms of the two constituents may replace each other within the same crystal structure.

Brass is similar to bronze, a copper alloy that contains tin instead of zinc.[2] Both bronze and brass may include small proportions of a range of other elements including arsenic, lead, phosphorus, aluminium, manganese and silicon. Historically, the distinction between the two alloys has been less consistent and clear,[3] and increasingly museums use the more general term "copper alloy".[4]

Brass has long been a popular material for its bright gold-like appearance and is still used for drawer pulls and doorknobs. It has also been widely used to make sculpture and utensils because of its low melting point, high workability (both with hand tools and with modern turning and milling machines), durability, and electrical and thermal conductivity. Brasses with higher copper content are softer and more golden in colour; conversely those with less copper and thus more zinc are harder and more silvery in colour.

Brass is still commonly used in applications where corrosion resistance and low friction are required, such as locks, hinges, gears, bearings, ammunition casings, zippers, plumbing, hose couplings, valves and electrical plugs and sockets. It is used extensively for musical instruments such as horns and bells. The composition of brass makes it a favorable substitute for copper in costume jewelry and fashion jewelry, as it exhibits greater resistance to corrosion. Brass is not as hard as bronze and so is not suitable for most weapons and tools. Nor is it suitable for marine uses, because the zinc reacts with minerals in salt water, leaving porous copper behind; marine brass, with added tin, avoids this, as does bronze.

Brass is often used in situations in which it is important that sparks not be struck, such as in fittings and tools used near flammable or explosive materials.[5]

  1. ^ Engineering Designer 30(3): 6–9, May–July 2004
  2. ^ Machinery Handbook, New York, Industrial Press, Edition 24, p. 501
  3. ^ Bearings and bearing metals. The Industrial Press. 1921. p. 29.
  4. ^ "copper alloy (Scope note)". British Museum. The term copper alloy should be searched for full retrievals on objects made of bronze or brass. This is because bronze and brass have at times been used interchangeably in the old documentation, and copper alloy is the Broad Term of both. In addition, the public may refer to certain collections by their popular name, such as 'The Benin Bronzes' most of which are actually made of brass.
  5. ^ "Hand Tools – Non-sparking tools". Canadian Center for Occupational Health and Safety. 1 December 2017. Retrieved 30 April 2022.