Brass is used in everything from plumbing fittings and electrical connectors to musical instruments, ammunition casings, and door hardware. It’s one of the most versatile metal alloys in existence, combining copper (50 to 95 percent) with zinc (5 to 50 percent) in ratios that can be tuned to emphasize different properties: corrosion resistance, malleability, electrical conductivity, or ease of machining. That flexibility is why brass shows up in so many industries.
Plumbing Fittings and Valves
Brass has been a staple in plumbing for generations because it resists corrosion from water, forms tight threaded seals, and lasts for decades. Faucets, shut-off valves, hose connectors, and pipe fittings are commonly made from brass alloys. The material holds up well in both hot and cold water systems and doesn’t degrade the way some plastics can over time.
One important shift in recent years involves lead content. Older brass plumbing components contained up to 8 percent lead to improve machinability. Under updated federal rules through the Safe Drinking Water Act, brass products that contact drinking water now must contain no more than a weighted average of 0.25 percent lead across their wetted surfaces. If you’re replacing old brass fittings in your home, look for products labeled “lead free” to meet this standard.
Electrical Connectors and Terminals
More electrical contacts, terminals, and switches are stamped from brass containing 30 percent zinc than from any other copper alloy. That might seem surprising, since this brass carries only about 28 percent of pure copper’s electrical conductivity. The tradeoff is worth it: brass is far easier to stamp into complex shapes, it resists corrosion at contact points, and it springs back reliably when plugged and unplugged repeatedly. For applications demanding higher conductivity, manufacturers use lower-zinc versions. A 5 percent zinc brass, for example, reaches 56 percent of copper’s conductivity while still being easier to form than pure copper. Because zinc costs less than copper, higher-zinc brasses also keep material costs down.
Musical Instruments
Trumpets, trombones, tubas, and French horns are all commonly made from brass, though the name “brass instrument” actually refers to how sound is produced (buzzing lips into a mouthpiece) rather than what the instrument is made of. Some brass instruments are built from other metals entirely. Still, brass is the dominant choice because it’s easy to bend into complex tubing shapes, takes a smooth polish, and resists tarnish from moisture and handling.
The shape of the tubing matters more to the sound than the metal itself. Cylindrical bore instruments like trumpets and trombones can produce the classic “brassy” blare because of how sound waves behave in straight tubing. Conical bore instruments like flugelhorns and tubas produce a mellower tone. Mouthpieces are typically machined from solid brass and shaped into three parts: a cup, throat, and backbore, each influencing how the player’s vibration enters the instrument.
Ammunition Casings
Most centerfire ammunition uses brass cartridge cases, and the reason comes down to one property: malleability. When a round fires, the expanding gases push the brass case outward so it forms a tight seal against the chamber walls. This prevents hot gas and carbon residue from blowing back into the action, reducing wear on the firearm. Steel casings, by comparison, are too rigid to form that seal reliably, which leads to more fouling and faster wear.
Brass cases can also be reloaded. Shooters resize the spent case back to its original dimensions, seat a new bullet, and fire it again. Brass tolerates this reforming without cracking or splitting, which makes reloading practical and keeps long-term ammunition costs lower for frequent shooters.
Germ-Killing Surfaces
Brass kills bacteria on contact, a property it inherits from its copper content. The surface releases copper ions that damage bacterial membranes, proteins, and DNA. In lab testing, brass surfaces reduced antibiotic-resistant bacteria by over 99 percent within just five minutes of contact, while stainless steel showed dramatically less effect. This held true across multiple resistant strains, including types related to staph and hospital-acquired infections.
That’s why brass doorknobs, handrails, and push plates have seen renewed interest in hospitals, schools, and public transit. The antimicrobial effect doesn’t wear off or require chemical treatment. It works passively, every time someone touches the surface.
Non-Sparking Safety Tools
In environments with flammable vapors, explosive dust, or volatile solvents, a single spark from a dropped wrench can be catastrophic. Brass is one of several alloys classified as “non-sparking,” meaning it produces far less risk of ignition on impact than steel. Wrenches, hammers, scrapers, and pry bars made from brass or bronze alloys are standard equipment in oil refineries, chemical plants, grain elevators, and ammunition factories. The Canadian Centre for Occupational Health and Safety lists brass alongside bronze and copper-beryllium alloys as approved materials for these settings.
Precision Machined Parts
Brass is the easiest common metal to machine. A specific alloy known as free-cutting brass holds a machinability rating of 100, which serves as the benchmark that all other metals are measured against. It cuts cleanly, produces small chips that clear away easily, and causes minimal tool wear. That’s why it dominates production of gears, lock cylinders, clock components, valve stems, and the countless small precision parts that fill industrial catalogs. When a manufacturer needs to produce thousands of identical threaded or knurled components at high speed, brass is usually the first material considered.
Marine Hardware (With Caution)
Brass appears throughout boats in the form of porthole frames, cabin hardware, and decorative fittings. However, it has a serious weakness in saltwater: dezincification. Seawater selectively corrodes the zinc out of brass, leaving behind a porous, pinkish copper shell that looks intact but has almost no structural strength. A dezincified propeller or through-hull fitting can crumble under load without warning.
For anything below the waterline, true bronze (a copper-tin alloy with little or no zinc) is the safer choice. Common marine brasses include red brass (85 percent copper, 15 percent zinc), naval brass (60/40), and admiralty brass (70/30), but even these carry dezincification risk in raw-water applications. Manganese “bronze,” despite its name, is actually a brass alloy with 40 percent zinc and is particularly vulnerable. If you’re replacing fittings on a boat, confirming whether a part is genuine bronze or just labeled that way can prevent a dangerous failure.
Decorative and Architectural Uses
Brass has a warm, gold-like color that makes it a popular choice for decorative hardware, light fixtures, cabinet pulls, and architectural trim. Low-zinc brasses (under 20 percent zinc) tend toward a reddish hue, while high-zinc “yellow brasses” with over 30 percent zinc have the bright gold tone most people associate with the metal. Over time, brass develops a natural patina that many people find attractive, though it can be polished back to a mirror finish.
Recycling and Sustainability
Brass is one of the most recycled metals. Construction and demolition waste containing brass and other metals has a recycling rate of roughly 70 percent in the United States. Unlike plastics, brass can be melted down and recast repeatedly without losing its essential properties. Scrap brass from old plumbing, spent casings, and obsolete hardware feeds back into foundries to produce new components, reducing the need for freshly mined copper and zinc. Newer hydrometallurgical recovery methods are making it possible to extract brass and copper from complex waste streams like electronics at lower temperatures, cutting energy use and emissions in the process.