Brass vs bronze: what's actually the difference?

What's actually different between brass and bronze?

The recipe. Brass is copper with zinc mixed in. Bronze, in the original sense, is copper with tin. That one ingredient swap sets the colour, the price, and the day job: brass became the bright, cheap, easy-machining metal, and bronze became the tough, slippery one that shrugs off seawater.

Bronze is the older idea by about three thousand years. Copper-tin bronze shows up around 3300 BC and mattered enough that we named the Bronze Age after it. Brass had to wait on zinc, which boils away at smelting heat. Roman founders made it by baking copper in crushed zinc ore so the vapour soaked in. Clever, slow, and expensive, which is why nobody talks about a Brass Age.

Here's the honest wrinkle: "bronze" stopped meaning just copper and tin a long time ago. It's now the family name for copper alloys built on almost anything except zinc. Aluminum bronze contains no tin at all. Phosphor bronze and silicon bronze are separate branches. And "manganese bronze", the boat-prop alloy, is roughly 39% zinc, which makes it a brass wearing a bronze badge. When the spec matters, trust the C number on the bar, not the nickname.

How do you tell brass from bronze by looking at them?

Start with colour on fresh metal. Brass is a clean, bright yellow, the colour of a trumpet or an old door handle. Bearing bronze is browner and redder, closer to a dull penny. File a small patch shiny before you judge, because weathered brass and weathered bronze both fade to the same tired brown.

The magnet test won't help. Brass and bronze are both copper alloys, and a magnet slides straight off each of them, so a magnet only proves the part isn't steel. The one part-exception is aluminum bronze: C954 carries 3-5% iron, enough that a strong magnet drags a little instead of letting go clean.

Aluminum bronze muddies the colour test too. It runs a pale gold that sits closer to brass than to penny brown. So if you're matching a mystery bushing on a machine that matters, don't trust shade at all. Match the grade off the drawing, the parts book, or the old supplier, and buy that.

Why are bushings bronze instead of brass?

Because bearing bronze was engineered to live against a rotating steel shaft, and brass wasn't. C932, the bearing trade's SAE 660, is roughly 83% copper, 7% tin, 7% lead, and 3% zinc. The tin dissolves into the copper and builds a strong, wear-resistant body. The lead never dissolves. It stays scattered through the casting as soft microscopic pockets.

Those pockets are the whole trick. Under load they smear across the running surface as a thin film, a lubricant cast right into the metal, still working when the grease schedule slips. Grit embeds in the soft lead instead of scoring the shaft. And the bronze stays a touch softer than hardened steel on purpose: the cheap, replaceable bushing wears so the expensive shaft doesn't.

Brass can stand in on light duty, a hinge pin or a hand-cranked roller. Put C360 against a loaded, spinning shaft, though, and it wears quickly, with nothing in its makeup feeding the running surface the way C932's lead does. If the part spins, slides, or carries thrust, make it bronze.

Which one survives salt water?

Bronze, and it isn't close. High-zinc brass has a failure mode all its own called dezincification: salt water slowly leaches the zinc out of the alloy and leaves a weak, spongy, copper-rich shell. The part holds its shape, looks nearly fine, and crumbles under the next real load. C360 brass is about 35% zinc, so it has plenty to lose.

The warning sign is colour: splotchy pink or reddish patches blooming on yellow metal mean the zinc is already leaving. Bronze mostly opts out of the disease. C932 carries only about 3% zinc and C954 essentially none, so there's nothing for the sea to strip. C954 goes a step further and grows a tough aluminum-oxide skin, which is why it earns marine hardware and pump duty.

That's the story behind boatyard wisdom too: proper seacocks, thru-hulls, and prop hardware are bronze. The classic trap is "manganese bronze" props, which are metallurgically brass and dezincify like one. Salt water, splash zone, or a trailer that gets dunked every weekend: buy bronze and stop thinking about it.

Is brass or bronze easier to machine?

Brass, and it's the yardstick for everything else. C360 sits at 100 on the machinability scale, the score other alloys are graded against. C932 bearing bronze rates about 70: its lead breaks chips the same way, so boring a bushing to size is quick, clean work. C954 aluminum bronze rates about 60 and makes you earn it.

Earning it means rigid setups, sharp carbide, and slower feeds, because C954 is strong: 85,000 psi minimum tensile as cast, about double C932, around 170 Brinell. In exchange you get gears, worm wheels, and wear parts that hold up under loads that would smear a softer bronze.

Two bits of shop trivia, both true. Bronze running on steel resists galling, the cold-welding seizure that ruins same-on-same metal pairs, which is half the reason worm gears ride bronze. And aluminum bronze doesn't spark like steel, so the non-sparking hammers and wrenches sold for refineries and grain elevators are aluminum bronze or beryllium copper. Already settled on brass and just need the grade? Our 360 vs 260 brass guide picks it in one question.

What do brass and bronze cost from our rack?

Brass is the cheaper buy, and bronze is sold differently, not just priced higher. Our C360 comes as drawn bar: flat, round, hex, and square, plus some sheet, cut to the inch. Our bronze is rotocast, meaning the molten metal was spun in a mould while it froze, which packs the casting dense and uniform. Most of it sells as tube sized for bushing blanks.

So you don't buy bronze by the foot the way you'd buy brass hex. Pick the tube whose bore and wall bracket your finished bushing, order a 1″ or 2″ slice from the rotocast bronze rack, and machine it to final size. Type your length in inches on the product page and the price shows up. Cuts are free, to ±1/8″.

The table tells you how to shop. A bushing job wants the $8.67 slice, not the $121.73 stick, so let the tube do the roughing for you. Volume discounts of 5-15% apply automatically as the order grows, the order minimum is $40, and prices update daily; our June 2026 metal price guide shows where brass and bronze sit against steel and aluminum. First time buying by the inch? Here's how cut-to-length ordering works.

Order by 1pm Atlantic on a business day and it usually ships the next business day, up to 96″ a piece, anywhere in Canada, or pick it up free at our Dartmouth shop. Need phosphor bronze, silicon bronze, or a C954 size you don't see online? Send a quote request and we'll source it, usually in 2-21 days, with the price in front of you before you commit.