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  for Metal Finishing since 1989
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Metal identification

Is there an easy way to tell the difference between silver and aluminum. If there is what is it. I looking at recycling for the wireless industries.

Thanks,

Johnny Fraley
- Plano, Texas
2003

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First of two simultaneous responses --

Dear Mr Fraley,

Assuming you only have aluminium or silver, you can tell the difference by immersing the part in warm is 50% nitric acid. If there is a reaction and the surface is attacked it is silver, if nothing happens it is aluminium.

Kind regards,

Sjamp van Esch
- Eindhoven, The Netherlands
2003

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Second of two simultaneous responses --

Nitric Acid attacks silver. Nitric Acid does not attack Aluminum.

Robert H Probert
Robert H Probert Technical Services

Garner, North Carolina

2003

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First of three simultaneous responses --

Nitric acid is hazardous and I wouldn't suggest it if there's a suitable alternative. I'm more of a kitchen chemist and "Draino" comes to mind. Straight caustic will dissolve the aluminum and leave the silver behind (might be a little gray or blackened, but basically intact).

Milt Stevenson, Jr.
Syracuse, New York
2003

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Second of three simultaneous responses --

You received good advice about nitric acid testing. But also note that silver weighs more than three times as much as aluminum, so a small amount of experience may help you immediately judge which one you are dealing with.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2003

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Third of three simultaneous responses --

Nitric is OK but highly obnoxious, dangerous and toxic. You can alternatively use muriatic (30% hydrochloric) acid or a solution of 20% caustic soda ⇦liquid caustic soda in bulk on Amazon [affil link] dissolved in tap water. Both will attack aluminum very fast but not silver.

Guillermo Marrufo
Monterrey, NL, Mexico
2003