How to identify scrap metal and tell copper from brass
Start with a magnet, then scratch a hidden spot and check the weight. Copper is reddish-gold, brass is yellow, and neither sticks to a magnet. No test is certain on its own. Never use sparks, flame or acid.
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To tell copper from brass, scratch a hidden spot and look at the bare metal. Copper is reddish-gold. Brass is yellow.
Copper, brass and bronze don't stick to a magnet, so colour, weight and what the item was are your best clues. Treat a home result as a good guess, not proof.
To compare 15 metals side by side, see the identification chart.
- About a thirdthe weight of aluminium against steel of the same size and shapeAustralian Aluminium Council
- Over 2 timeshow much heavier common zinc die-cast alloys are than aluminiumInternational Zinc Association, Royal Society of Chemistry
- About 5%the weight gap between copper and 70/30 brass, too small to tell them apartRoyal Society of Chemistry, Wieland Concast
- Nopull from a magnet on copper, brass or bronzeCanadian Conservation Institute
What are the safe home tests?
Try these four in order and stop when you are sure. Each one narrows the options.
No test is certain on its own, so use two or three together. Test a clean spot on something you own.
| Test | How to do it | What it tells you | What it can't tell you |
|---|---|---|---|
| 1. Magnet | Hold a strong magnet on a flat, clean spot. A fridge magnet is often too weak. | A firm stick means steel, iron, cast iron or a magnetic stainless steel. No stick rules out plain steel and iron. | Which non-magnetic metal you have. A weak pull can mean a steel screw, spring or core. |
| 2. Scratch | Scratch a hidden spot with a key or knife tip. Look at the bare metal, not paint, rust or tarnish. | The true colour: reddish-gold copper, yellow brass, silvery-white aluminium. Grey under a coloured coat means plating. | Which alloy it is. Alloys cannot be told apart by colour alone. |
| 3. Weight | Lift it and compare it with a steel item of the same size. | Aluminium weighs about a third as much as steel. Lead weighs more than steel. | Copper from brass, or stainless steel from plain steel. Their weights are too close. Hollow or thin pieces can also mislead. |
| 4. Use and stamps | Think about where the item came from. Check the underside for a stamp. | Pipe and wire are usually copper. Taps, valves and keys are usually brass. A stamp may name the grade, such as 304 or 316. | Anything about parts that were re-used or plated. |
Source: Canadian Conservation Institute, Canadian Conservation Institute notes, Royal Society of Chemistry on copper, Royal Society of Chemistry on aluminium, Australian Aluminium Council, checked 2 October 2026
If the magnet sticks firmly, see scrap steel and iron to sort light iron, heavy steel and cast iron.
Do
- Scratch a hidden spot, such as an underside, a thread or a cut end
- Use two or three tests together
- Compare weight with a steel item of the same size
- Photograph what you find and tell the buyer
Don't
- Judge by paint, rust, plating or dirt
- Trust colour alone
- Treat a home result as proof
- Test items you don't own
How do you tell copper from brass and bronze?
Scratch a hidden spot and compare the bare colour. The Royal Society of Chemistry calls copper a reddish-gold metal. The Canadian Conservation Institute says brass is quite yellow, though it can be red. It says bronze runs from a warmer gold than brass to golden brown.
Use is a good clue. Pipe and electrical wire are usually copper. Taps, valves, fittings, keys and door hardware are usually brass. Bearings, bushes, boat fittings and statues are often bronze. The scrap copper and scrap brass pages list the grades of each that Forge Recyclers buys.
The names overlap. The Recycled Materials Association (ReMA) publishes scrap specifications for buyers and sellers. It describes red brass scrap, such as valves and machinery bearings, as castings made of copper, tin, zinc and/or lead. It also lists some grades as bronze/brass. So a yard may use a different word from you for the same piece.
Two traps catch people out.
| Trap | What you see | How to check |
|---|---|---|
| Plated steel | A copper or brass colour that a magnet sticks to | Scratch an edge. Grey metal shows under the coat. The Canadian Conservation Institute says brass-plated iron is magnetic. |
| Nickel silver | A silvery metal with no silver in it. It can pass for stainless steel or aluminium. | It is much heavier than aluminium. A stamp such as EPNS names it. Stainless steel needs an analyser test. |
Source: International Copper Association, Canadian Conservation Institute notes, University of Illinois, checked 2 October 2026
If you need certainty, an analyser can test it. The British Metals Recycling Association says X-ray fluorescence (XRF) is a key tool for metal recyclers to identify alloys and sort them into grades. You can't match that by eye, and you don't need to before you ask for a quote.
Is stainless steel magnetic?
It depends on the grade. Stainless steel is a family of alloys, not one metal.
| Family | Does a magnet stick? |
|---|---|
| Austenitic, such as 304 and 316 | Not when annealed. Heavy bending or pressing can add a weak pull. |
| Ferritic, such as 430 | Yes |
| Martensitic | Yes |
| Duplex | Yes |
Source: British Stainless Steel Association, Carpenter Technology, World Stainless, Euro Inox, checked 2 October 2026
A sink shows the problem. The British Stainless Steel Association says the flat drainer can have little magnetic response, while the pressed bowl has more. So one sink can give two answers, and a strong pull doesn't prove it is plain steel.
A magnet also can't tell one stainless grade from another. Carpenter Technology says a grade's magnetic response varies with its chemistry and how much it has been cold worked.
Grade matters for value, so look for a stamp on sinks, tanks and fittings, or ask us when you send photos. What scrap metal is worth the most explains why. For grades 304, 316 and 430, see the stainless steel scrap page.
How do you tell aluminium from zinc die-cast?
Cast zinc alloys and aluminium are both silvery, and neither sticks to a magnet. Both turn up in handles, housings and small fittings, so they are easy to mix up. Weight tells them apart.
The Australian Aluminium Council says aluminium can weigh one third as much as steel of the same size and shape. The Royal Society of Chemistry gives aluminium's density as 2.70 g per cm3. The International Zinc Association lists common zinc die-casting alloys at 6.6 to 6.8. So a zinc part weighs more than twice as much as an aluminium part of the same size.
The Association also says makers can finish zinc castings to look like solid gold, weathered brass or stainless steel. A chrome-look handle that doesn't stick to a magnet but feels heavy may be zinc. Hold two parts of similar size side by side. The heavier one is the zinc.
The chart shows how heavy each pure metal is for its size. Zinc die-cast alloys weigh a little less than the pure zinc shown.
Density is the weight of one cubic centimetre. Compare pieces of the same size. Steel is mostly iron and weighs about 7.85 (Australian Steel Institute), so iron is a fair guide for steel. Alloys differ a little from these pure-metal values.
View as a table
| Item | g per cm3 |
|---|---|
| Lead | 11.3 |
| Copper | 8.96 |
| Iron | 7.87 |
| Tin | 7.29 |
| Zinc | 7.13 |
| Aluminium | 2.7 |
Sources: Lead, Royal Society of Chemistry periodic table; Copper, Royal Society of Chemistry periodic table; Iron, Royal Society of Chemistry periodic table; Tin, Royal Society of Chemistry periodic table; Zinc, Royal Society of Chemistry periodic table; Aluminium, Royal Society of Chemistry periodic table; Designing for galvanizing (density of steel), Australian Steel Institute. Checked 2 October 2026.
For all 15 metals, see the identification chart.
Which tests should you never use?
Some online guides suggest spark testing, burning or acid. Skip all three.
When should you ask us to identify it?
If two or three tests disagree, or the pile is large or valuable, let us identify it. Take these photos first.
Photos to send
Start on the quote page, add your photos to the form, and Forge Recyclers replies with what to do next.
Before any pick-up, read what to sort and leave out in the preparation guide. For the ID and records a buyer may ask for, see selling scrap metal in Queensland.
Frequently asked questions
Does a magnet stick to brass?
Not normally. Brass is copper and zinc, and neither is magnetic. The Canadian Conservation Institute says brass-plated iron does stick. A strong pull usually means steel under a brass-coloured coat. A weak pull can mean a steel screw or spring inside. Scratch a hidden spot to see what is underneath.
Is stainless steel magnetic?
It depends on the grade. Ferritic, martensitic and duplex grades stick to a magnet. Austenitic grades such as 304 don't when annealed, but Carpenter Technology says heavy cold working can make 304 weakly magnetic. A magnet can't tell you which grade you have.
Can vinegar tell copper from brass?
No. Vinegar doesn't identify a metal. A gentle scratch on a hidden spot shows the colour without chemicals. Brisbane City Council lists corrosive and toxic items as hazardous waste, so keep acids out of an identification job. If the colour is still unclear, send us a photo.
How can I tell solid brass from brass-plated steel?
Hold a magnet to it. A strong pull means steel under the plating. Then scratch a hidden spot. Yellow metal underneath suggests solid brass, and grey metal suggests plating. Weight won't settle it, because brass and steel are close (about 8.5 and 7.85 g per cm3).
What could it be if a magnet does not stick?
Copper, brass, bronze, aluminium, zinc, lead or a non-magnetic stainless steel grade are the usual candidates. Use colour and weight next. Reddish-gold and heavy suggests copper, yellow and heavy suggests brass, and silvery and light suggests aluminium. Confirm with a scratch on a hidden spot.
How do I tell aluminium from stainless steel?
Pick both up. Aluminium can weigh about a third as much as steel of the same size and shape (about 2.7 against 7.85 g per cm3). Stainless steel weighs about the same as steel. A magnet won't help, because both can be non-magnetic. A heavy silvery item is not aluminium.
Sources
- Magnetic properties of stainless steels, Carpenter Technology (checked 2 October 2026)
- Mechanical and physical properties of stainless steels, World Stainless (International Stainless Steel Forum) (checked 2 October 2026)
- Aluminium properties, Australian Aluminium Council (checked 2 October 2026)
- Copper attributes and alloys, International Copper Association (checked 2 October 2026)
- Alloys, Zinc Die Casting, International Zinc Association (checked 2 October 2026)
- Copper, Royal Society of Chemistry periodic table (checked 2 October 2026)
- Aluminium, Royal Society of Chemistry periodic table (density 2.70 g per cm3) (checked 2 October 2026)
- ReMA ISRI Scrap Specifications Circular (grade names such as red brass), Recycled Materials Association (checked 2 October 2026)
- A to Z of metal recycling, British Metals Recycling Association (checked 2 October 2026)
- Don't bin your batteries, Queensland Government (checked 2 October 2026)
- Hazardous waste disposal, Brisbane City Council (checked 2 October 2026)
- Air and odour complaints, backyard burning, Brisbane City Council (checked 2 October 2026)
- Basic care: recognizing metals and their corrosion products, Canadian Conservation Institute (checked 2 October 2026)
- Identifying archaeological metal (CCI Notes 4/1), Canadian Conservation Institute (checked 2 October 2026)
- Object materials, Preservation Self-Assessment Program, University of Illinois (checked 2 October 2026)
- Is stainless steel non-magnetic? British Stainless Steel Association (checked 2 October 2026)
- Stainless steel: tables of technical properties, Euro Inox (2007), hosted by World Stainless (checked 2 October 2026)
- Die casting brochure, International Zinc Association (checked 2 October 2026)
- C26000 cartridge brass data, Wieland Concast (checked 2 October 2026)
- Designing for galvanizing (density of steel), Australian Steel Institute (checked 2 October 2026)
- ReMA's ISRI Specifications, July 2026, Recycled Materials Association (checked 2 October 2026)
Related pages
Got scrap metal to sell?
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