Brass is an alloy, or combination, of copper and zinc. Ancient civilizations in the Near East and the Roman Empire produced it in small amounts more than 2,500 years ago, using it for decorative purposes and to produce objects such as cooking pots, utensils and armor. It was not mass-produced until the 18th century, when a reliable metallurgy processing method for producing the high temperatures (1,665 F) required to melt zinc was discovered.
Brass has been manufactured, albeit in a rudimentary form, since ancient times: some archaeologists believe as far back as the Early Stone Age. But brass never had an "age" of its own, like the Bronze or Iron ages, because the technology required to produce enough heat to melt one of its ingredients, zinc, was not available in the primitive societies of those periods. Brass was first produced in the Near East approximately 2,500 years ago and from there the knowledge of how to make it spread to Europe. It was used to make decorative objects, pots, utensils, armor and coins until the 18th century, when new metallurgy processes made it possible to mass produce it. It has been used increasingly in manufacturing applications up to the present day.
Properties of Brass
The properties of brass vary according to the ratio of copper (55 to 90 percent) to zinc (10 to 45 percent) and the addition of small amounts of other metals such as tin, aluminum, lead and nickel. A good conductor of heat and electricity, brass is valued for its strength and malleability, which means it is both durable and easy to shape and stamp when making hardware and decorative objects. It also has acoustic abilities that make it a good choice in the manufacture of metallic musical instruments. Brass has anti-corrosive abilities that make it useful for naval hardware applications, and its antimicrobial characteristics are valued in hospital settings where the spread of infection is a concern. Hospital-acquired pathogens such as MRSA cannot survive on brass doorknobs and fingerplates for more than a few hours. Brass presents in colors that range from red to gold to silver, depending on its composition.
Brass is forged using cold working methods or hot rolling methods. Cold working is used for brasses that contain less than 40 percent zinc; hot rolling methods are used for brass alloys that contain more than 40 percent zinc. Cold working methods (alpha brasses) are used to produce screws, pins, bolts and ammunition cartridges. Hot rolling methods (beta brasses) are used to make tubing, jewelry, clock parts, springs, flanges, faucet handles, sprinkler heads and door and window fittings. Brass also can be cast in molds and extruded.
The brass industry is well-organized when it comes to recycling its scrap, which makes new brass items manufactured from it more economical, about 40 percent cheaper than brass produced from ore. Brass made from scrap is also ecologically sustainable, because it saves natural resources that would be expended producing it from copper and zinc. Brass scrap is made from pieces trimmed off during manufacturing, called offcuts, and scrap from machining, stamping and presswork, called swarf. This recycled scrap is easily melted and reformed, another way that using it keeps down the cost of producing articles made from it.