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How to assay silver

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  • How to assay silver

    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

  • #2
    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!
    Just got my head together
    now my body's falling apart

    Comment


    • #3
      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

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      • #4
        http://www.contenti.com/products/testing/450-217.html
        Also download the PDF instruction sheet.
        Glen
        Been there, probably broke it, doing that!
        I am not a lawyer, and never played one on TV!
        All the usual and standard disclaimers apply. Do not try this at home, use only as directed, No warranties express or implied, for the intended use or the suggested uses, Wear safety glasses, closed course, professionals only

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        • #5
          Dumb idea

          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.

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          • #6
            "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
            Just got my head together
            now my body's falling apart

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            • #7
              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.
              Free software for calculating bolt circles and similar: Click Here

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              • #8
                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
                Just got my head together
                now my body's falling apart

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                • #9
                  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

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                  • #10
                    "Besides, a few mg of gun cotton might be fun "

                    A few mg of guncotton is a lot of fun

                    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.
                    Just got my head together
                    now my body's falling apart

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                    • #11
                      Originally posted by Evan
                      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..."
                      Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                      ~Practitioner of the Electromechanical Arts~

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                      • #12
                        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.
                        Free software for calculating bolt circles and similar: Click Here

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                        • #13
                          I was always taught that silver turned milky white when exposed to the acid treatment not black.Alistair
                          Please excuse my typing as I have a form of parkinsons disease

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                          • #14
                            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.

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                            • #15
                              "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.
                              1601

                              Keep eye on ball.
                              Hashim Khan

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