Copper, Brass or Bronze? How to Tell

Copper, brass and bronze are related. Brass is copper mixed with zinc, and bronze is copper mixed mainly with tin. They are graded and paid differently, so it is worth telling them apart before you come in. You need good light, a magnet, and a file or some sandpaper.

Colour

• Copper: reddish-pink when clean, turning brown and eventually green as it ages.
• Brass: yellow, like gold, going dull and brownish as it tarnishes.
• Bronze: reddish-brown or dull gold, darker and browner than brass.

Tarnish hides the colour, so look at a fresh surface. File or sand a small spot until it shines: copper shows salmon pink, brass bright yellow, and bronze a reddish gold.

The magnet test

None of the three is magnetic. If a magnet sticks, it is not solid copper, brass or bronze. It is plated or painted steel, or there is steel inside it, such as a screw or an insert.

Where each one turns up

• Copper: water pipe, electrical wire, busbar, and the inner tank of some older hot water systems.
• Brass: taps, valves, plumbing fittings, keys, door handles and hinges, and ornaments.
• Bronze: bearings and bushes, valve bodies, boat propellers and fittings, statues and plaques.

How they are graded

Copper goes into the copper grades, from bright wire to No. 1 and No. 2, depending on how clean it is. Brass goes as mixed brass, or as coast brass when it is clean and unplated. Gun metal, the bronze used in valve bodies and bearings, is bought with mixed brass. For other bronze, send us a photo.

Keep the three apart. Brass fittings left on copper pipe take the copper down a grade, and a mixed bag is graded on what is actually in it.