Typically, brass is comprised of 67% copper and 33% zinc. As a general rule, the more zinc, the lighter the color of the brass.
Brass is an alloy of zinc and copper. Low zinc alloys will exhibit a darker red hue and are often referred to as red brass. Though zinc will always be the second most prevalent metal in brass, the addition of other metals such as tin, arsenic, iron and antimony are commonly included to further improve the physical and mechanical properties of the alloy. While the appearance of brass adds to its desirability, these manipulated features such as strength, hardness and formability more often determine the utility of brass in a given application.
Brass exhibits many of the physical properties of pure copper to some degree. Malleable and a relatively good conductor of heat and electricity, easily machined brass is commonly used in screws, casings, heat exchanges, pressure vessels and electrical equipment. As brass is stronger than pure copper and resistant to corrosion it is also employed in numerous tubing and piping applications. Non-sparking brass is popular in petrochemical processing industries as well as more commonplace settings requiring low friction such as in locks, gears, bearings, doorknobs, ammunition and valves. The list of applications in which brass is a popular choice is extremely long and variable from radiators to a host of musical instruments.
Like its base metal copper, brass is relatively malleable and thus easily formed through a number of manufacturing processes. Before machining, however, brass production must begin with combining the appropriate amounts of copper, zinc and other metals. To achieve this, the suitable metal scrap is weighed and transferred in pre-specified amounts into a furnace.
An electric furnace is commonly used as the temperature needs to reach 1920°F (1050°C). At such temperatures the metal becomes molten allowing for homogenization of the final product. If needed additional scrap is added to the mixture. Once the proper re-crystallization occurs, the metal is poured or cast into stock shapes and allowed to cool before further processing. These billets and ingots are then hot or cold rolled, extruded and cut into more finished stock shapes. Stock brass comes in a number of forms, the selection of which depends on the final product. Brass bars, plates, sheets, foils, strips, rods and more are designated by the specific features of their alloyed composition.
All brass alloys are first designated by the letter C, for copper which is then followed by a five digit number which provides suppliers and manufacturers with more information. Numbers beginning with one through seven signify brass that can be machined or forged, while numbers starting with eight or nine can only be finished through casting. It is important to consider these and other features such as length, weight, width, shape and elemental composition with regard for the intended use of brass forms.