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FIELD GUIDE
Brass vs bronze: how to tell them apart.
Brass and bronze are both copper alloys, both gold-ish to red-ish, and both non-magnetic — which is why sellers mix them up. Four field tests, in order, settle it: color, magnet, weight and markings, and the file scratch.
TEST 1 — COLOR
Gold-yellow vs reddish-brown
Color is the fastest test and it's right most of the time. Brass runs gold-yellow (copper plus zinc); bronze runs reddish-brown (copper plus tin). Hold the piece in good light and compare it to something you know.
The honest caveat: tarnish lies. Old brass goes brown and old bronze goes dark, and red brass sits between the two. If the color is ambiguous, don't guess — move to test 4.
TEST 2 — MAGNET
Neither one sticks
Brass and bronze are both non-magnetic: a magnet won't grab either one. This test doesn't separate brass from bronze — it separates both of them from steel and from plated junk.
If the magnet sticks firmly, the piece is steel or iron — possibly with a thin brass or bronze-colored plating. Test several spots: a steel screw in a brass valve will grab the magnet locally without meaning the whole valve is steel.
TEST 3 — WEIGHT, MARKINGS & HISTORY
Heavy, stamped, or obvious by origin
Both are dense — a brass or bronze part feels heavy for its size compared to aluminum or zinc die-cast. Bronze typically feels a touch heavier than brass, but that's a tiebreaker, not a test.
Markings beat guessing. Mill products are often stamped with C-numbers — C360, C932, C521 — and the stamp is the final word. And consider what the piece was: plumbing fittings and valves lean brass; bearings, bushings, and gears lean bronze. What the C-numbers mean.
TEST 4 — FILE SCRATCH
The honest test under the tarnish
Take a file to a hidden edge and scratch through the surface. Gold-yellow scratch: brass. Reddish-brown scratch: bronze. Gray underneath: plating over steel — not solid at all.
One thing the internet gets wrong: the spark test. Grinding a piece to read its sparks is a steel-shop test — it tells you about carbon in steel, and it tells you nothing useful about brass or bronze. Don't grind your brass; file it.
WHEN IN DOUBT
Don't guess — text a photo
If the four tests still leave you unsure, that's normal — the line between red brass and bronze is genuinely hazy, even for buyers. Text a clear photo of the piece to 312-880-8174 and we'll call it for you before you drive anywhere.
RELATED
Keep reading the brass & bronze dictionary.
Brass & Bronze Dictionary — the full hub of alloy-by-alloy guides. Yellow Brass — the gold-yellow workhorse. Bronze — the copper-plus-tin family. How Brass & Bronze Get Graded — what the ID protects.
FREQUENTLY ASKED QUESTIONS
Brass vs bronze questions, answered.
Will a magnet stick to brass or bronze?
No. Neither brass nor bronze is magnetic. If a magnet sticks, the piece is steel or iron — possibly plated to look like brass or bronze.
What is the easiest way to tell brass from bronze?
Color: brass is gold-yellow, bronze is reddish-brown. When tarnish hides the color, a file scratch on a hidden edge shows the true metal underneath.
Should I do a spark test on brass or bronze?
No. The spark test is a steel test — it reads carbon in steel and tells you nothing about copper alloys. File the piece instead of grinding it.
What if I still can't tell what I have?
Text a photo to 312-880-8174 — we'll identify it for you. https://ironcrestindustrialsurplus.com/brass-vs-bronze has the full four-test walkthrough.
Text a photo of your brass or bronze to Sonny at 312-880-8174 — or call 312-880-8174 for today's number.
TODAY'S NUMBER
Call for today's number.
Prices move with the market daily. Text a photo of your brass or bronze and get today's number — quoted against the market, honored at pickup. Same-day pickup in Chicago — and I'll travel nationwide for the right load.
HOW SELLING WORKS
Three steps to an offer.
Material review
We review what the material is, its condition and quantity, and whether it fits a direct purchase.
Receive an offer
For qualifying material, we discuss a direct purchase offer and the next steps.