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orionstarman
Penny Pincher Member
USA
106 Posts |
 Posted - 06/27/2009 : 20:11:10
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Is there some type of easy way to check the purity of silver bars or coins/rounds. I know that way back in the way backs there was something called a "touchstone" that was used to check the purity of gold. A person would rub the gold coin in question on the touchstone and could tell by the color of the mark left behind how pure it was. Is there any thing that simple for silver?
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Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.--Benjamin Franklin
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Country
1000+ Penny Miser Member
USA
3121 Posts |
Posted - 06/27/2009 : 20:24:57
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| Purity is one of the reasons I continue to like US 40% and 90% silver coins. When the going gets tough, how will you know that the bars and rounds are pure? Heck, how do you really know your 100 oz. bar is real today? |
---> Come to the new and improved realcent: http://realcent.org
The things that will destroy America are prosperity-at-any-price, peace-at-any-price, safety-first instead of duty-first, the love of soft living, and the get-rich-quick theory of life.
– Theodore Roosevelt
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Market Harmony
1000+ Penny Miser Member
USA
1274 Posts |
Posted - 06/27/2009 : 21:23:30
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quote:
Originally posted by orionstarman
Is there some type of easy way to check the purity of silver bars or coins/rounds. I know that way back in the way backs there was something called a "touchstone" that was used to check the purity of gold. A person would rub the gold coin in question on the touchstone and could tell by the color of the mark left behind how pure it was. Is there any thing that simple for silver?
Nitric Acid is used to test purity ranges. It is not extremely accurate, however. And, it only tells you ranges, at best. Basically, you either scratch the silver onto a testing stone and then apply the nitric acid solution, or if it is just bullion, then you can apply the nitric acid directly onto the bar. This will dull any finish.
The reaction of nitric acid applied directly on silver will turn different colors and shades. .900 to .999 and the nitric acid is deep red, or almost purple on top and creamy / light gray when you wipe away the acid. .770 to .900 is less red reaction, and dark gray when you wipe away the acid. .650 to .750 has a greenish reaction, and is light green when wiped away.
Some people claim that you can judge the purity by how reactive the acid is with the silver, but this is garbage. Nitric acid can be either diluted or old and less acidic. And nobody is good enough to give you the exact purity by just looking at the reaction. It is best to first test a known purity, and then do the same test on the piece in question. This gives you a base of knowledge first.
Nitric acid is dangerous stuff. Do not inhale the fumes, or get the acid on your skin. Do not get the dissolved silver (silver nitrate) on your skin as it will stain for days. The same goes for your sink, or whatever else the silver nitrate touches... it stains! Do not dump nitric acid down your drain as it will dissolve the metal. Wear thick rubber gloves and eye protection. Keep the reaction away from flame. Neutralize the acid with baking soda before discarding. |
goto the new and improved realcent: http://realcent.org |
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goldsilverpro
Penny Sorter Member
26 Posts |
Posted - 06/27/2009 : 22:58:41
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No offense but, except for the last paragraph, everything that Market Harmony just said is incorrect.
When nitric acid is put onto silver, it definitely does not produce a red color. If the silver is pure, the solution will be colorless.
What he had in mind was the use of Schwerter's solution, a combination of potassium dichromate, nitric acid, and distilled water. On pure silver, a drop of this will turn bright red. On sterling (92.5% silver), it will turn dark red. Here is a writeup on using this method.
You must be logged in to see this link. |
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Country
1000+ Penny Miser Member
USA
3121 Posts |
Posted - 06/28/2009 : 09:42:59
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| Goldsilverpro/Market Harmony - Your methods may detect if the surface of an object has a certain silver fineness. More to orionstarman's question, how would you check the purity of a silver bar? The silver bar could be silver plated or filled with metals of density similar to silver. Would the only way to check purity be to slice or drill a hole in the bar to test its insides for silver content? Would counterfeit rounds be done likewise? Is there a way to test, perhaps by harmonic sound testing, for purity without test cuts (in ancient times test cuts were common, especially on the ancient greek coins)? |
---> Come to the new and improved realcent: http://realcent.org
The things that will destroy America are prosperity-at-any-price, peace-at-any-price, safety-first instead of duty-first, the love of soft living, and the get-rich-quick theory of life.
– Theodore Roosevelt
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Edited by - Country on 06/28/2009 10:40:30 |
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orionstarman
Penny Pincher Member
USA
106 Posts |
Posted - 06/28/2009 : 10:01:10
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| Maybe something like the way the Ryedale scans copper pennies would work. You could put a standard of a known purity in some type of device and wave it over the coin/bar in question and get a red light green light kind of thing. |
Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.--Benjamin Franklin
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Edited by - orionstarman on 06/28/2009 10:03:22 |
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Market Harmony
1000+ Penny Miser Member
USA
1274 Posts |
Posted - 06/28/2009 : 10:13:49
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quote:
Originally posted by goldsilverpro
No offense but, except for the last paragraph, everything that Market Harmony just said is incorrect.
Any time that you must preface a statement by "no offense" you should immediately rethink exactly what you are about to say.
I have considerable doubts that the instructions are incorrect from which I was copying the information in my post. So, I decided to pull out some silver and the nitric acid solution and prove it... Here:
That reaction looks red to me, and the instructions are on the bottom.
If you reread my post, you'll see that I did use the word "solution" and not "high purity nitric acid" I have commonly heard the solution being referred to as just "nitric acid" from jewelers and coin shop owners. Nitric acid is clear in itself. And is used to dissolve precious metals in the refining process. Form what I have found, the highest purity that is commercially available was 80%. I believe it can be made pure through distilation, but I have never tried.
I've used plenty of this stuff to know how it works, it's shortcomings, and what it is really good for... only determining a large range of silver purity. However, I've tested this on other metals and have gotten false results. So really, these tests are not worth much my in my opinion.
I'm sure you meant the best for other readers by making your post. However, immediately discreditting me was not right. If you'd like to dispute anything about the testing, please do not tell it to me. I purchased the nitric acid solution from You must be logged in to see this link. and the solution and instructions are made by You must be logged in to see this link. Take it up with them. |
goto the new and improved realcent: http://realcent.org |
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Market Harmony
1000+ Penny Miser Member
USA
1274 Posts |
Posted - 06/28/2009 : 11:02:58
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quote:
Originally posted by Country
Goldsilverpro/Market Harmony - Your methods may detect if the surface of an object has a certain silver fineness. More to orionstarman's question, how would you check the purity of a silver bar? The silver bar could be silver plated or filled with metals of density similar to silver. Would the only way to check purity be to slice or drill a hole in the bar to test its insides for silver content? Would counterfeit rounds be done likewise? Is there a way to test, perhaps by harmonic sound testing, for purity without test cuts (in ancient times test cuts were common, especially on the ancient greek coins)?
Depending on the thickness of the plating, the nitric acid solution should dissolve the thin layer and then dissolve the base metal to show that the piece is not solid silver. You'll be able to see the color change.
Silver does have a distinctive ring to it when struck. But determining the purity based on the harmonics would require calculations and special equipment. Certainly, if you strike a bar and there is no ring, then you might have either struck it incorrectly or it is not solid silver.
Drilling and then assaying the drill sample has been common practice to determine the purity of large bars. You would have to contract with a lab to do this. Alternatively, you can remelt the silver to get a homogenous mix, cast it, then do a surface test.
For small rounds, I don't know why counterfeiting would be done unless the item would be able to sell at much higher to spot prices, such as numismatics. But if there was doubt, then a nondestructive test with a You must be logged in to see this link. would give you the assurance of purity. |
goto the new and improved realcent: http://realcent.org |
Edited by - Market Harmony on 06/28/2009 11:03:37 |
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Country
1000+ Penny Miser Member
USA
3121 Posts |
Posted - 06/28/2009 : 12:01:16
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Market Harmony - Thanks for you answers.
However, from what you stated, there doesn't seem to be any simple test available. It almost seems that you've got to take your silver bar to an expert to have it evaluated.
As for small rounds, I was thinking about the Chinese counterfeit rounds that will be coming our way (especially at higher silver spot prices) in the not too distinct future. |
---> Come to the new and improved realcent: http://realcent.org
The things that will destroy America are prosperity-at-any-price, peace-at-any-price, safety-first instead of duty-first, the love of soft living, and the get-rich-quick theory of life.
– Theodore Roosevelt
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orionstarman
Penny Pincher Member
USA
106 Posts |
Posted - 06/28/2009 : 18:18:00
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Well, based on the response so far it looks like there may be no simple test for the purity of silver coins/bars other than the faith and trust you place in the person you buy them from.
2000 years ago people were using gold and silver for money. In order for something to used for money it has to be excepted by everyone. In order for it to be excepted the people would have to know if it were truly gold or silver. If they had no easy and independent way of knowing if it was truly gold or silver than they had to depend on the word of the person they were taking it from, which almost makes it no better than fiat money.
I think that with the enormous cost and risk of life and limb that was involved in trading 2000 years ago a merchant would not set off across a dessert on a 2,3 or 4 month journey if they didn't know how to tell the difference between fake silver or silver of low quality from pure or high quality silver. I don't know maybe it was just experience if you handle silver every day you get to know it's feel and look and taste and sound.
It just seems to me that in this day and age that we might have a simple way to check. WTSHTF how do you convince someone that has never handled silver in their life to take your silver bar for that new set of tires or food or what ever? Having a ton of silver bars in my basement will do me no good if I can't easily convince people it is what I say it is. Trust will be something hard to come by WTSHTF. |
Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.--Benjamin Franklin
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Edited by - orionstarman on 06/28/2009 20:51:20 |
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theo
Penny Hoarding Member
USA
588 Posts |
Posted - 06/28/2009 : 20:23:04
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I'm no expert here, but wouldn't sizing and weighing the coin/bar on a digital scale give an assurance of pure silver with a 90% to 95% certainty? Doesn't every metal have its own weight/density? For example, lets say that I took a 1967 Washington Quarter, painted the sides silver and changed the date to "1961." My fake would be exposed by the fact that it weighs about .5 grams less on a digital scale (not to mention the chiming sound).
It would be similar with bars. If a standard size 5 ounce bar was actually silver plated copper it would probably weigh about 4.6 ounces since I believe copper is a little less dense than silver. You could, of course, mix a little lead in to increase the weight, but then the bar would be slightly attracted to magnets.
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theo
Penny Hoarding Member
USA
588 Posts |
Posted - 06/28/2009 : 20:38:18
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quote:
Originally posted by orionstarman
Well, based on the response so far it looks like there may be no simple test for the purity of silver coins/bars other than the faith and trust you place in the person you buy them from.
2000 years ago people were using gold and silver for money. In order for something to used for money it has to be excepted by everyone. In order for it to be excepted the people would have to know if it were truly gold or silver. If they had no easy and independent way of knowing if it was truly gold or silver than they had to depend on the word of the person they taking it from, which almost makes it no better than fiat money.
I think that with the enormous cost and risk of life and limb that was involved in trading 2000 years ago a merchant would not set off across a dessert on a 2,3 or 4 month journey if they didn't know how to tell the difference between fake silver or silver of low quality from pure or high quality silver. I don't know maybe it was just experience if you handle silver every day you get to know it's feel and look and taste and sound.
It just seems to me that in this day and age that we might have a simple way to check. WTSHTF how do you convince someone that has never handled silver in their life to take your silver bar for that new set of tires or food or what ever? Having a ton of silver bars in my basement will do me no good if I can't easily convince people it is what I say it is. Trust will be something hard to come by WTSHTF.
I see your point, however IMHO its probably best to avoid bartering with bars. Barter would most-likely be easier with commonly-known coins like 90% silver coins, 40% halves and even SAEs and Maple Leafs. If things fall a part I think the average person will become a coin expert fairly quickly. |
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orionstarman
Penny Pincher Member
USA
106 Posts |
Posted - 06/28/2009 : 21:37:42
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quote:
I see your point, however IMHO its probably best to avoid bartering with bars. Barter would most-likely be easier with commonly-known coins like 90% silver coins, 40% halves and even SAEs and Maple Leafs. If things fall a part I think the average person will become a coin expert fairly quickly.
I think that I would have to agree with that. When the hyperinflation sets in I think the SAEs and 90% silver coins would be more far more acceptable than bars and other rounds. I like the idea of the lower premiums on the generic rounds and bars but when push comes to shove the SAEs may hold a higher value than the generics because they are more recognizable. |
Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.--Benjamin Franklin
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goldsilverpro
Penny Sorter Member
26 Posts |
Posted - 06/28/2009 : 23:39:33
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Market Harmony,
That solution in your photo is not a nitric acid solution. Technically, when you say that, you are saying that it only contains nitric acid plus a solvent, such as water, which is not true. What it is is a solution that contains nitric acid - huge difference. It is actually called Schwerter's solution, a solution that contains potassium dichromate and nitric acid. You could have said that it's a nitric acid/potassium dichromate solution. If they called it a nitric acid solution on the instruction sheet, then they are in error.
This is not just an exercise is semantics. It is an exercise in communications. If someone had tried to follow what you said, it would not have worked because your instructions were incomplete.
Aqua regia is made up of nitric acid and hydrochloric acid and is used to dissolve gold. Similarly, this is not a nitric acid solution. It is an aqua regia solution or, a solution that contains nitric acid and hydrochloric acid. You could boil gold for 100 years in a nitric acid solution and you wouldn't dissolve any gold. Communications. |
Edited by - goldsilverpro on 06/30/2009 14:57:18 |
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goldsilverpro
Penny Sorter Member
26 Posts |
Posted - 06/30/2009 : 10:26:11
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Back to the original question. The following covers a few ways to test for fakes. I'm sure there are more.
Concerning pure silver (999, or better) coins and bars.
First of all, pure silver is the whitest metal on the planet. All other metals (with the exception of gold and copper, the only metal elements with color) will be some shade of gray, as compared side-by-side with pure silver. There is a look-alike alloy of nickel and copper, containing no silver, that is called German silver or nickel silver. However, when compared side-by-side with pure silver, the color difference is obvious.
The only 3 ways I can think of to counterfeit pure silver coins or bars are: (1) Make them from a solid non-silver alloy. (2) Make them from a solid non-silver alloy and plate them with silver. (3) Make them with pure silver, drill out the center, and fill them with a low melting point metal, such as lead or tin/lead.
The incentive to counterfeit silver bullion coins is not that great because they're not that costly to start with. The cost of counterfeiting could easily exceed the profits. Large silver bars are another story, as are gold coins.
To test coins that are supposedly pure silver.
Destructive methods. The most accurate method is to drill a couple of holes or file a deep notch on the edge and analyze the drillings or filings. I doubt if that's what you had in mind.
Non-destructive methods. (1) or (2) above are the most likely ways coins would be faked. The use of (3) is doubtful because of the difficulty of drilling and filling a small coin without screwing up the appearance. Also, it is difficult to pour molten metal in a small hole because it will seal up.
First of all, compare the details of the coin carefully (maybe, use an eye loupe) with that of an identical coin you know to be real. The details of the fake coin will likely be inferior. Drop the coin on a hard surface and compare the ring with that of a real coin. Weigh the coin and compare this with a real coin. Do the same with the dimensions of the coin, especially the thickness (use a micrometer) in specific areas of the detail.
If the method of (1) is used, the different color can be detected by comparing it with a real coin. If (2) is used, the details will be less sharp due to the plating. You can also determine the specific gravity or test it with an XRF tester. (See below)
To test bars.
Although methods (1) or (2) could be used, (3) is the only method I have ever seen used. I have only seen it used on cast bars of 100 oz or larger. When using method (3) the drilled hole has to be plugged with silver. If they used another metal as a plug, you would see the color difference. In each case, this plug was on the end of the bar and could be seen by careful examination. They ground it down flush but you could still see it.
Destructive methods. Drill it through in about 6 likely scattered spots and analyze the drillings. If you hit a filling, such as lead, the drillings will be a different color.
Non-destructive. Measure the specific gravity. Have an x-ray made of the bar, if you suspect method (3) was used.
For 90% coins, etc.
All the methods are about the same as above. For non-destructive testing, compare the quality of the minting, the color, the weight, the dimensions, etc., with that of a real coin. Determine the specific gravity of both the suspected fake and a real coin and compare the results.
XRF equipment - Niton, etc. This equipment non-destructively determines the metals in the particular alloy. However, since it only penetrates about 0.3" (as I have been told), it would only be valuable for types (1) and (2) above.
Specific gravity. Technically, although this is not exactly the same as Density, the 2 terms are often used interchangeably. It involves weighing the object (in grams) in air normally, then weighing it suspended in distilled water and making a calculation. S.G. = (weight in air)/(weight in air - weight in water). Every material has it's own S.G. (expressed in grams per cubic centimeter) - pure water is 1, aluminum is 2.7, tin is 7.3, copper is 8.9, molybdenum is 10.2, silver is 10.49, lead is 11.3, gold is 19.3.
The problem is weighing it in water. Some inexpensive scales, such as the Ohaus Cent-o-gram and Dial-o-gram, have a built-in pan to do this, although their weight limit is 311 grams - 10 tr.oz. The Ohaus triple beam will weigh up to about 5 pounds (with the extra weights) and it has a pin near the bottom, underneath the pan, that can be used to hang the object.
About any scale can be jury-rigged to hang the object. For example, a digital scale can be set on the small end of an ironing board. A zeroed (tared) dowel, with a strong thread (or, fishing line) hanging off each end, could be laid across the pan of the scale. Underneath, the threads are tied to the object. Books are piled up and a vessel of water is placed on the books. The object is hung in the water, without the object or the threads touching the sides of the vessel, and is weighed. Bubbles can attach themselves to the object, especially when is is dirty, and this can cause inaccuracy. It helps to add a drop of soap to the water. You can also tap the object gently with a rod to dislodge the bubbles before weighing.
The accuracy is dependent on the weight of the object (the bigger, the better) and the sensitivity of the scale. For a coin, I would use a scale that reads down to at least .01 grams and, better still, .001 grams.
The fake bars I saw were filled with lead and this could be easily detected by measuring the S.G. However, with an alloy of tin and lead, the S.G. of silver could be duplicated. In general, if the measured S.G. is not 10.49 (for fine silver), or within a few points of it, the item is fake. This assumes, of course, that everything was done correctly. However, if the S.G. is 10.49, that is not necessarily proof that the object is pure silver.
I know that this is rambling, but I hope it helps.
Edit: I just found this S.G. determination thread. It's pretty good. Read the whole thread. He's using wire and compensating for it in the calculation. To see the full calculation, click on the link at the beginning of the first post.
You must be logged in to see this link. |
Edited by - goldsilverpro on 06/30/2009 21:28:57 |
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orionstarman
Penny Pincher Member
USA
106 Posts |
Posted - 06/30/2009 : 20:12:22
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quote:
Originally posted by goldsilverpro
Back to the original question. The following covers a few ways to test for fakes. I'm sure there are more.
Wow, that's some good info. but not quite what I had in mind. It does however help answer my question. It seems that the easiest way to make sure your getting silver WTSHTF is to only except what you know and trust to be silver in the first place. ASEs, pre 1964 U.S 90% coins and other coins with an known pedigree and to shy away from the generic rounds or to except them at a discount. |
Those who would give up essential liberty to purchase a little temporary safety deserve neither liberty nor safety.--Benjamin Franklin
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goldsilverpro
Penny Sorter Member
26 Posts |
Posted - 06/30/2009 : 21:09:02
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| I think that counterfeits are a rarity, although they surely exist. In most cases, the stuff is real. I would not shy away from bullion but I would be cautious and buy in small amounts, rather than large. Probably, you'll get an honest deal. But, there's always that 1 chance in a 1000, or more! Bullion coins are probably safer than bars, although both are generally safe. I, personally, wouldn't fear either of them. In my 40+ years of being in the PM refining business, on a professional level, I have never seen a counterfeit silver coin, although I have seen counterfeit Chinese gold coins. I have seen 2 or 3 counterfeit (lead filled) cast 100 oz silver bars out of the many 1000s that I have been involved with. I have never seen a minted silver bar, of any size, that has been counterfeit. |
Edited by - goldsilverpro on 06/30/2009 21:41:26 |
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NotABigDeal
1000+ Penny Miser Member
USA
3890 Posts |
Posted - 07/01/2009 : 06:20:48
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quote:
Originally posted by goldsilverpro
I think that counterfeits are a rarity, although they surely exist. In most cases, the stuff is real. I would not shy away from bullion but I would be cautious and buy in small amounts, rather than large. Probably, you'll get an honest deal. But, there's always that 1 chance in a 1000, or more! Bullion coins are probably safer than bars, although both are generally safe. I, personally, wouldn't fear either of them. In my 40+ years of being in the PM refining business, on a professional level, I have never seen a counterfeit silver coin, although I have seen counterfeit Chinese gold coins. I have seen 2 or 3 counterfeit (lead filled) cast 100 oz silver bars out of the many 1000s that I have been involved with. I have never seen a minted silver bar, of any size, that has been counterfeit.
Really? I have a few fake silver Pandas here somewhere, and have seen pretty nice fakes of trade dollars and Morgans.
Deal |
Live free or die.
Plain and simple.
"If you love wealth more than liberty, the tranquility of servitude better than the animating contest of freedom, depart from us in peace. We ask not your council or your arms. Crouch down and lick the hand that feeds you. May your chains rest lightly upon you and may posterity forget that you were our countrymen."
- Samuel Adams |
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Market Harmony
1000+ Penny Miser Member
USA
1274 Posts |
Posted - 07/01/2009 : 06:22:23
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quote:
Originally posted by goldsilverpro
... it only contains nitric acid plus a solvent, such as water... What it is is a solution that contains nitric acid. It is actually called Schwerter's solution, a solution that contains potassium dichromate and nitric acid...
Thanks for the chemistry lesson. It was never my strong suit, so my definition of solution was not the same as what a real "solution" is. I do appreciate your response. It's good to learn this information.
quote:
Originally posted by goldsilverproAqua regia is made up of nitric acid and hydrochloric acid and is used to dissolve gold. Similarly, this is not a nitric acid solution. It is an aqua regia solution or, a solution that contains nitric acid and hydrochloric acid. You could boil gold for 100 years in a nitric acid solution and you wouldn't dissolve any gold. Communications.
Did I imply that the solution was good for testing or dissolving gold? I did not intend to do so. There are other testing solutions that I have for gold, but I have the same confidence in them that I have in the silver testing solution.
In regards to a simple silver test, is there a way to test via electrical impedance or thermal conductivity to get purity? Would the other metals change the conductivity or impedance and therefore indicate the silver content? Or, is this type of test not sensitive enough, or the alloying does not alter the impedance or conductivity to a testable degree? I've never seen or heard of any such thing, but it seems plausible in theory. It would be interesting to see a chart of conductivity along an axis of alloys of silver. The type of base metal would be important to note. A 90/10 Ag/Cu alloy conductivity would be very different from a 90/10 Ag/Pb alloy. |
goto the new and improved realcent: http://realcent.org |
Edited by - Market Harmony on 07/01/2009 06:36:13 |
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Market Harmony
1000+ Penny Miser Member
USA
1274 Posts |
Posted - 07/01/2009 : 06:34:13
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quote:
Originally posted by goldsilverpro
...In my 40+ years of being in the PM refining business, on a professional level...
Did you or do you work for a major refiner?
I've have heard of, but never tried, some ways to refine copper in its liquid state, but I have not found any info on the same for silver. Is there a way to do this? Or, is the only way to refine silver via dissolving in a nitric acid solution?
I have seen considerable pick up of oxidized metals in some tests that I've done with just a bit of boric acid in a charge of 80% silver alloys.
Do you refine on the side? If so, I could be able to bring some good business to you. |
goto the new and improved realcent: http://realcent.org |
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goldsilverpro
Penny Sorter Member
26 Posts |
Posted - 07/02/2009 : 13:16:38
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quote:
Really? I have a few fake silver Pandas here somewhere, and have seen pretty nice fakes of trade dollars and Morgans.
NotABigDeal.
I was a refiner and most of the garbage was weeded out before I got it. Also, people don't generally send in Pandas or Trade Dollars or Morgans for refining. We did get in large cast silver bars. How were these coins faked? Unplated base metal? Silver plated base metal? Or, what? How did you determine that they were fakes?
Market Harmony.
quote:
Did you or do you work for a major refiner?
I've have heard of, but never tried, some ways to refine copper in its liquid state, but I have not found any info on the same for silver. Is there a way to do this? Or, is the only way to refine silver via dissolving in a nitric acid solution?
I have seen considerable pick up of oxidized metals in some tests that I've done with just a bit of boric acid in a charge of 80% silver alloys.
Do you refine on the side? If so, I could be able to bring some good business to you.
I appreciate your offer, but I've been retired for several years. Now, I just post on several PM and plating forums. I am a moderator on goldrefiningforum.com and have made over 2000 posts there. Same name - goldsilverpro. Same avatar.
To answer your question, I have been refining since 1966. I was the Senior Chemist for what was, at that time, the largest refinery West of the Mississippi and was General Manager for what was, at that time, the largest refinery in Asia. I have consulted for quite a few refineries and have owned 2 refineries.
By a liquid state, do you mean in a molten state. If so, I know of no practical method that most other metal impurities can be removed from silver by smelting, with the exception of iron and some less common metals.
The standard way of refining silver is in a silver cell. Impure silver bars are dissolved electrolytically in a silver nitrate/copper nitrate solution and 9999 silver crystals are plated out on a cathode, which is usually a sheet of stainless. There's a lot of info about this on goldrefiningforum.com
In order to form oxides with base metals in a melt, you need a source of oxygen. When you melted with borax, you got a little oxygen from the air. Besides borax, you could add niter (sodium nitrate), as an oxygen source, but this is impractical, since it also attacks the crucible. You would burn out many crucibles before your silver became pure. You can remove certain metals by piping oxygen gas through the molten metal. However, with copper, the most common impurity found in silver, this would take forever and you still wouldn't get it all. Also, with prolonged heating at high temperatures, the silver tends to evaporate. |
Edited by - goldsilverpro on 07/02/2009 13:37:36 |
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TXTim
Penny Hoarding Member
629 Posts |
Posted - 07/02/2009 : 13:52:31
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Very interesting thread!
Thanks for the great education, guys!!! |
Beer is my currency. |
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Coll3ctor
Penny Pincher Member
USA
222 Posts |
Posted - 07/02/2009 : 16:16:06
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quote:
Originally posted by NotABigDeal
quote:
Originally posted by goldsilverpro
I think that counterfeits are a rarity, although they surely exist. In most cases, the stuff is real. I would not shy away from bullion but I would be cautious and buy in small amounts, rather than large. Probably, you'll get an honest deal. But, there's always that 1 chance in a 1000, or more! Bullion coins are probably safer than bars, although both are generally safe. I, personally, wouldn't fear either of them. In my 40+ years of being in the PM refining business, on a professional level, I have never seen a counterfeit silver coin, although I have seen counterfeit Chinese gold coins. I have seen 2 or 3 counterfeit (lead filled) cast 100 oz silver bars out of the many 1000s that I have been involved with. I have never seen a minted silver bar, of any size, that has been counterfeit.
Really? I have a few fake silver Pandas here somewhere, and have seen pretty nice fakes of trade dollars and Morgans.
Deal
What he said ^^^^ 90% of the fakes are coming out of Asia. I would never touch any Chinese bullion as there is so much crap out there that you never know what you might be getting. Look on eBay at all of the fake olympic sets still for sale  I think it's just a matter of time before China expands the varieties of their counterfeiting  |
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goldsilverpro
Penny Sorter Member
26 Posts |
Posted - 07/07/2009 : 12:11:26
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Although several methods were mentioned, I still think that testing the specific gravity of the gold or silver bars or coins would be the best method. It is non-destructive. It is within the means and capabilities of almost anyone. If you do it accurately, it is very objective.
Most fake silver coins are probably made from copper alloys. This could easily be detected by the S.G. or by just weighing and measuring them. Any lead alloys would would produce a dull thud when rung and it would be difficult to get good definition when minting.
For gold coins, it would be virtually impossible to fake the specific gravity unless they used platinum, osmium, or iridium. They couldn't use tungsten because it's virtually uncastable and can't be rolled. The S.G. of gold is usually given as 19.32. If you look up the S.G. of tungsten, you'll find values from 19.25 to 19.62. This may be because of the difficulties of obtaining a true solid chunk of it. The only tungsten I've found on the internet is made using compacted, sintered tungsten powder and has an S.G. of about 17-18.
One time, a guy brought us about 250 Chinese gold coins, all sealed in large plastic sheets with pockets. He had 1 coin loose that he used as a sample. The sample checked out and the 250 looked OK through the plastic. We simply weighed the loose coin and then got a total weight on the 250 coins still in the plastic. Even with the plastic, the 250 coins weighed about half of what they should weigh - gold plated copper. The guy that brought them in had bought them cheap and I believe that he really thought they were the real deal.
Here's an interesting series of gadgets that check the dimensions and weights of certain (mainly gold) coins. In essence, they are checking the S.G. They are way too expensive and I can't see them being as accurate as the standard scale method of testing the S.G.
You must be logged in to see this link. |
Edited by - goldsilverpro on 07/07/2009 12:30:42 |
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n/a
deleted
478 Posts |
Posted - 07/07/2009 : 15:20:31
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Inside a Chinese counterfeit Morgan Dollar factory:
You must be logged in to see this link.
The Fisch detectors are great but very expensive. They measure the coins several different ways, size, thickness and the gage is used to weigh it also. You'd want to have lots of gold and silver to make the Fisch worth it. However, if it saved you from buying a fake one ounce gold coin, it would be worth it alone. It's a personal choice. I have one for a particular gold coin and I only buy that type so it's good for piece of mind.
The most common faked gold coins are the English sovereign, Mexican Peso and anything from China. I'd avoid all of these. Just my 2 cents. |
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goldsilverpro
Penny Sorter Member
26 Posts |
Posted - 07/09/2009 : 19:33:33
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quote:
They measure the coins several different ways, size, thickness and the gage is used to weigh it also.
In other words, they check the specific gravity.
The counterfeit coin link you gave is very interesting. There are 2 types of counterfeit coins:
Fake bullion coins would have to be made of less valuable metals in order to make a profit. The Fisch device or specific gravity measurements would detect this in short order.
Fake collectible coins, on the other hand, would have to be made of the correct alloys, in order to be successful. The Fisch device and S.G. would both be worthless in this case. Also, if the minting and aging quality were good, they could fool an expert. |
Edited by - goldsilverpro on 07/09/2009 19:56:13 |
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Simple test for silver purity?
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