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topic 23897

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


A discussion started in 2003 but continuing through 2018

2003

Q. 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


2003

A. The only dead 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 except when you want the color of a penny; brass is much yellower.

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


2003

thumbs up sign  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

Q. 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

A. 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, or the stanchions for the velvet ropes at a movie theatre, I'd call it brass.

Copper is closer to being pure, about 99.3% for what is called pure copper, but somewhat less than that for what are called dilute copper alloys. 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 the bottom of 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, then claiming that you adhere to some specific ASTM spec, I'm not sure that you can go much further than that. For what reason must you give it the name brass or copper with such positivity?

Regards,

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



March 24, 2018

Q. I have a lamp which is a warrior on a horse, saying Good-bye to his love. Three stained glass shades. Cannot find markings. Bought out of a 100 yr old house. Any ideas on date made?

Teri Coleman
- Hempstead, texas USA


March 2018

A. Hi Teri. This site focuses on metal finishing technology rather Antiques Roadshow issues. But if you mail a photo to we'll post it here; and then your likelihood of getting a response will be greatly improved, although it's probably still low.

Without a picture or markings, there's actually no reason to assume that an artist/craftsperson didn't fabricate it yesterday. Good luck.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"



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