Brass is an alloy of copper and zinc with proportions ranging from roughly 5% to 45% zinc. Unlike bronze, which pairs copper with tin, brass offers a distinctive golden colour, excellent machinability, and a lower melting point than either constituent metal. The alloy has been manufactured for at least 2,500 years, with Roman-era brass production using the cementation process: heating copper with the zinc ore calamine in a closed crucible. Modern brass production simply melts copper and zinc together, allowing precise control over composition and properties.
Key Alloy Grades
Cartridge brass, designated C260 under the Unified Numbering System, contains 70% copper and 30% zinc. This single-phase alpha brass combines excellent cold-working properties with a tensile strength of roughly 330 MPa in the annealed condition. Its name comes from its historic use in ammunition cartridge cases, where deep drawing required a metal that could stretch uniformly without tearing. The same properties make C260 ideal for architectural trim, lighting fixtures, and jewellery.
Free-cutting brass C360 adds roughly 2.5% to 3.7% lead to the copper-zinc matrix. The lead particles, insoluble in the brass, act as chip breakers during machining, allowing fast cutting speeds and long tool life. This grade achieves a machinability rating of 100%, the benchmark against which all other copper alloys are measured. Plumbing fittings, valve bodies, and screw-machine products dominate its market. Environmental regulations increasingly restrict lead in drinking-water components, pushing manufacturers toward lead-free alternatives such as bismuth-containing brasses, though these come at higher cost and with slightly reduced machinability.
Naval brass C464 contains approximately 60% copper, 39.2% zinc, and 0.75% tin. The tin addition improves resistance to dezincification in seawater, making this alloy the standard for marine hardware: propeller shafts, turnbuckles, and fasteners below the waterline. Its tensile strength of roughly 380 MPa matches that of mild structural steel.
Dezincification and DZR Brass
Dezincification is a selective corrosion process in which zinc leaches preferentially from brass exposed to certain water chemistries, leaving behind a porous, weakened copper sponge. Soft, acidic waters with high chloride content and low temporary hardness pose the greatest risk. Dezincification-resistant (DZR) brass contains small additions of arsenic, typically 0.02% to 0.06%, or antimony, which suppress the cathodic reaction that drives zinc dissolution. European standard EN 12164 mandates DZR brass for drinking-water fittings in designated risk areas, and UK water regulations require DZR components in all new installations since the late 1990s.
Musical Instruments and Hardware
Brass is the defining material of the orchestral brass family: trumpets, trombones, French horns, and tubas. Instrument makers prefer alloys around 70% copper for their combination of formability and acoustic properties. Hand-hammered brass instrument bells, formed on a mandrel from flat sheet, achieve a superior tone through work-hardening and variable wall thickness. In domestic hardware, brass doorknobs and handles exploit both the metal's warm colour and its inherent antimicrobial properties. Testing at the University of Southampton in 2015 showed that brass door furniture harbours far fewer bacteria than stainless steel equivalents, with the copper content providing ongoing passive disinfection in high-touch environments.