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ZINOM
03-26-2007, 10:05 AM
Hi Guys,

I have some stuff that I THINK may be silver (left to me by a friend along with some of her art school stuff), and I'm wondering if is in fact silver.

Does anyone know if there is a home method to assay the metal, or if it would be common for a local jeweler to be able to do it in-house.

I would like to maybe make my wife a little ring or something but I'd like to know what I'm working with first.

Thanks for your help,

John

Swarf&Sparks
03-26-2007, 10:11 AM
Only sure method I know is the old "eureka!" But that requires a precise balance and a way to measure displacement.

Probably not practicable in small quantities, and if you go running down the street naked these days, you're gonna get busted!

Steve Steven
03-26-2007, 10:23 AM
Check on the Chaski board, guy named Harold, who is a moderator there, used to be in precious metals and has a lot of experience in this area., he can help you. Try this for URL, it might be right:
http://www.chaski.org/homemachinist/

Steve

PTSideshow
03-26-2007, 10:31 AM
http://www.contenti.com/products/testing/450-217.html
Also download the PDF instruction sheet.

ckelloug
03-26-2007, 10:38 AM
Take a sliver of the material. Put a few drops of strong nitric acid on it. If it turns black in sunlight, it's silver. If you spill it on yourself and then go out in the sun then it leaves a black spot you can't get off. . . Probably also an acid burn if you don't neutralize the acid before you spill it. . .

Note, the chemistry is correct but I have not done this. YMMV.

Swarf&Sparks
03-26-2007, 10:47 AM
"Take a sliver of the material. Put a few drops of strong nitric acid on it. If it turns black in sunlight, it's silver."

Errm, nope. Means it contains silver.

To take an extreme case, that test would work on old B&W film. As well as dissolving the celluloid backing all over your fingers, you would create guncotton :(

Evan
03-26-2007, 11:38 AM
Measure the thermal conductivity. Hold a small thin piece in your fingers and apply a flame nearby. If you detect an urgent need to drop it almost immediately it contains silver. None of the other white metals even come close. Aluminum is only half as conductive and zinc is about 1/4th.

Swarf&Sparks
03-26-2007, 11:45 AM
Evan, I've TIG welded aluminium.
It's conductive enough for me.
Felt an urgent need to rip my glove off to stop it burning my knuckle to the bone :D

ckelloug
03-26-2007, 11:47 AM
Ya Got me Swarf.

That's why I titled the post dumb idea. Doesn't gun cotton need a trace of Sulphuric acid as a catalyst to work right though? The metal test kit is definitely the easy good answer. The drop of nitric acid will tell you however that it isn't steel, isn't gold. If you have a mixture, then better chemistry is needed.

Besides, a few mg of gun cotton might be fun :D

Swarf&Sparks
03-26-2007, 11:52 AM
"Besides, a few mg of gun cotton might be fun :D"

A few mg of guncotton is a lot of fun :D

Anyway, unless you have more than a few gm of the (possibly) precious metal, would it not make more sense to sell it to a jeweller who can assay it?
You could then purchase sterling silver to do with as you choose.

Weston Bye
03-26-2007, 12:37 PM
Measure the thermal conductivity. Hold a small thin piece in your fingers and apply a flame nearby. If you detect an urgent need to drop it almost immediately it contains silver. None of the other white metals even come close. Aluminum is only half as conductive and zinc is about 1/4th.

"If you detect an urgent need to drop it almost immediately... "
Edit to read: "If you smell something stupid burning, drop it immediately..."

Evan
03-26-2007, 12:43 PM
It would be obvious if it is aluminum by the weight. That leaves metals that are no more than 1/4 or worse conductivity. Easy to tell, especially if you have ever made silver jewelery. Further, if it looks like silver it will usually be tarnished. German silver will not be. If it does contain silver it will likely be 80% or better.

If it looks tarnished then put it in a cup lined with aluminum foil and filled with warm salt water. If it brightens in a few minutes it's mainly silver. Pewter and or zinc won't lighten.

Alistair Hosie
03-26-2007, 01:38 PM
I was always taught that silver turned milky white when exposed to the acid treatment not black.Alistair

ckelloug
03-26-2007, 03:30 PM
Silver chloride is a white powder which comes from reacting silver with Hydrochloric Acid. Sivler nitrate which comes from Silver plus Nitric Acid is more of a clearish stuff that turns black when exposed to UV.

J Tiers
03-26-2007, 04:53 PM
"German silver", at least of the "nickle silver" variety, tarnishes just fine....... it turns a yellowish color and eventually gets to a near-black if exposed to sulphur-containing pollution.

We had plenty of trouble with it used as electrical connections on jacks where it was the "thru" connection if you didn't plug in. Opened the connection right up after a few months. We changed the plating.

Your Old Dog
03-26-2007, 07:16 PM
This is not scientific by any means but...........


Remember, there was a time when silver was very cheap to buy for artist. So, depending on when she bought this stuff...........

I have a lot of silver wire and silver sheet in my engraving tool box. All of it is tarnished to some extent. Also, if it's firm to bend try heating it and letting it cool and see if it anneals easier than you expect. (just drawing .010 fine gold wire thru a birthday candle anneals it on the spot)

Daminer
09-05-2007, 03:10 PM
Try to track down Harold V on the chaski board, he was/is involved in precious metal refining.....

http://www.chaski.org/homemachinist/

Considering cost and safety aspects of working with assaying chemicals, might be a lot cheaper and faster to find a jeweler who buys precious metals to work up an analysis for you.....

Jim

old-biker-uk
09-05-2007, 04:27 PM
Chromic acid solution, tiny (I mean tiny) drop on the test piece, immediate rinse off in water, an orange stain (silver chromate) indicates silver, brighter the colour, the higher the silver content. Good rough guide if you don't have a metalurgical lab in the basement.
No orange precipitate - no silver
Mark

stuntrunt
09-06-2007, 10:51 AM
If you clean the metal with some fine steelwool (wirewool) and put it between some other whitish metals of which you know what they are and that had the same wirewool treatment, it should be reasonably obvious. Put them next to eachother under the same lamp and look at the edges and darker (shadow) parts.
Nickel silver has a blue to green subtone
Ferrous metals tend to be very grey
Lead and pewter are grey as well, with a purple tinge
Aluminium is absolutely monochrome
White gold looks a bit like lead when unpolished
Silver is has a straw-yellow subtone.
It's propably not platinum -you'd know.
You can also compare to iridium if you have an expensive fountain pen or a siringe.
Also, the softer the silver, the purer it is...

SGW
09-06-2007, 11:02 AM
Mark Twain describes in considerable detail how to do a silver assay in his book "Roughing It."