Brass has a muted yellow color, somewhat similar to gold. It is relatively resistant to tarnishing, a layer of corrosion, and is often used as decoration and for coins. In antiquity, polished brass was often used as a mirror.
Brass has likely been known to humans since prehistoric times, even before zinc itself was discovered. It was produced by melting copper together with calamine, a zinc ore. In the German village of Breinigerberg, an ancient Roman settlement was discovered where a calamine ore mine existed. During the melting process, the zinc is extracted from the calamine and mixes with the copper. Pure zinc, on the other hand, has too low a boiling point to have been produced by ancient metalworking techniques. The many references to 'brass' appearing throughout the King James Bible are thought to signify another bronze alloy, or copper, rather than the strict modern definition of 'brass'.
The malleability and acoustic properties of brass have made it the metal of choice for brass musical instruments such as the trombone, tuba, trumpet, euphonium, and the French horn. Even though the saxophone is classified as a woodwind instrument and the harmonica is a free reed aerophone, both are also often made from brass. In organ pipes designed as "reed" pipes, brass strips are used as the "reeds".
Brass has higher malleability than copper or zinc. The relatively low melting point of brass (900 to 940°C, depending on composition) and its flow characteristics make it a relatively easy material to cast. By varying the proportions of copper and zinc, the properties of the brass can be changed, allowing hard and soft brasses. The density of brass is approximately .
Today almost 90% of all brass alloys are recycled. Because brass is nonmagnetic, it can be separated from ferrous scrap by passing the scrap near a powerful magnet. Brass scrap is collected and transported to the foundry where it is melted and recast into billets. Billets are heated and extruded into the desired form and size.
Aluminum makes brass stronger and more corrosion resistant. Aluminum also causes a highly beneficial hard layer of aluminium oxide (Al2O3) to be formed on the surface that is thin, transparent and self healing. Tin has a similar effect and finds its use especially in sea water applications (naval brasses). Combinations of iron, aluminum, silicon and manganese make brass wear and tear resistant. A well known alloy used in the automotive industry is 'LDM C673', where the combination of manganese and silicon leads to a strong and resistant brass.
The copper in brass makes brass germicidal, via the oligodynamic effect. For example, brass doorknobs disinfect themselves of many bacteria within eight hours. This effect is important in hospitals, but useful in many contexts.
Brass door hardware is generally lacquered when new, which prevents tarnishing of the metal for a few years when located outside (and indefinitely when located indoors). After this most manufacturers recommend that the lacquer is removed (e.g. with paint stripper) and the items regularly polished to maintain a bright finish. Unlacquered brass weathers more attractively than brass with deteriorated lacquer, even if polishing is not carried out. Freshly polished brass is similar to gold in appearance, but becomes more reddish within days of exposure to the elements. A traditional polish is Brasso.
Brass was used to make fan blades, fan cages and motor bearings in many antique fans that date before the 1930s. Brass can be used for fixings for use in cryogenic systems, however its use is not limited to this.
Due to its natural heat conducting properties and its availability, brass was used to create the infamous Brazen Bull, a torture and execution device in ancient Greece.
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