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topic 23897

How do you identify if old lamp is brass or copper or bronze?


I have an old lamp that needs to be cleaned, it had green and red spots but after using some vinegar it only has some of the red spots left..

What is best way to clean those and how do you tell what metal it is?

Jason Hall
- Fort Lauderdale, Florida, United States


The only easy step is to test it with a magnet. If it's magnetic, it is plated steel rather than either brass or copper. Copper is not as strong and stiff as brass, and is more expensive, so it usually isn't used for lamps. Copper is the color of a penny, brass is much yellower.

Ted Mooney, Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey


Thank You, the Lamp is not magnetic although the thinner pieces are golden and the thicker parts of the lamp have a deeper darker color. It looks like two different types of metal.

Jason Hall (returning)
- Ft. Lauderdale, Florida

November 30, 2010

I have applied Brasso [linked by editor to product info at Amazon] to a hundred year old Middle Eastern coffee table. Initially it was almost black, and now it's as shiny as a penny. How do I MAKE SURE that it's actually copper and not brass. Is there a simple "homegrown" procedure to differentiate between both metals?

Joe Bigio
- Clearwater, Florida USA

November 30, 2010

Hi, Joe. I'm not sure that your question is quite as meaningful as you would like it to be.

Brass is an alloy of zinc and copper, generally ranging from about 60% copper (muntz metal), through 70% (cartridge brass) on up to about 85% (red brass). If the table is the color of a bullet cartridge, or a lamp, I'd call it brass.

Copper is closer to being pure, about 99.3% for what is called pure copper, and somewhat less than that for what is called a dilute copper alloy. The impurity metals may be zinc, or lead, or iron, etc. If it's the color of a penny or a piece of wire or a Revereware pot, I'd call it copper.

Short of having x-ray fluorescence analysis performed and coming up with an exact grade or exact chemical analysis, I'm not sure that you can go much further than that. For what reason must you give it the name brass or copper?


Ted Mooney,
Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

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