# Removing Silver from Electrical Contacts- Harold?



## Fever (Apr 1, 2007)

I got these massive electrical contacts from a condemed workshop onboard an old WW2 submarine tender that I had free access to (yea, what a time capsule!). I have not done a file test on these yet, and they just might be solid silver, which means I have quite a few ounces sitting here, and many more in a bucket from the same acquirement. 

I have two questions.

1. If they are indeed pure silver, or a high-silver alloy, would I have to melt them and shot them prior to processing in Nitric, or can is there a better method?

2. If they are plated, I would think the sheer amount of this material that I have would still warrant processing. How would I get the heavy silver plate from the contacts? Is there a similar system to Steve's reverse electroplating that would work for silver?

Thank you sir...... Fever


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## Harold_V (Apr 1, 2007)

Fever said:


> 1. If they are indeed pure silver, or a high-silver alloy, would I have to melt them and shot them prior to processing in Nitric, or can is there a better method?
> 
> 2. If they are plated, I would think the sheer amount of this material that I have would still warrant processing. How would I get the heavy silver plate from the contacts? Is there a similar system to Steve's reverse electroplating that would work for silver?
> 
> Thank you sir...... Fever



Stripping of plating is easily accomplished by sulfuric cells, although I doubt that the contacts are just plated. A current density of 90 amps/square foot of anode is desirable, with a sulfuric specific gravity of 1.65. That's how the original patented cells were run------without glycerin. I'd be interested in hearing what purpose it has in the process-----I no longer do any of this work so can't experiment to see for myself. Only on this forum did I first hear of using glycerin. 

To recover the values on large contacts, it's usually desirable to get the silver contact off the copper buss, which may be silver plated. You'd recover the trace values from the copper buss when you used the copper to recover silver from the contacts, which would be digested in nitric and water. Melting of the copper buss might be required, or stripping the surface silver so it can then precipitate silver from your nitrate solution. The copper buss is an excellent source of needed copper. 

Melting contacts isn't always possible, which will become obvious when you start processing them. They are typically silver soldered to the buss, or base piece, and are usually removed before processing. When you remove them from the buss, which can be accomplished with a torch (oxy/acet, or natural gas and oxygen) you'll find at least two types, one of which is predominantly tungsten. They're heavier than other contact types, although usually thinner, and have a waffle pattern on the back side. Extracting the silver from this type contact is slow business, taking hours in a heated solution of nitric and water to penetrate the honeycomb of silver and tungsten. You're left with the tungsten, which crumbles easily once the silver is removed. A break test easily shows if silver has been totally extracted, or not. Best thing to do is run a few of anything you may have in your possession to become familiar with how they behave. Once you understand the behavior, you can formulate your own plan, that works for your particular setup. 

I don't know what is alloyed with silver in other contacts, but they are usually not pure. There is residue after the silver has been extracted, often a pale yellow colored powdery material, and easily separated from the silver nitrate solution simply by allowing it to settle. Decant the solution with a small hose, don't pour. 

Light duty contacts may contain cadmium----contacts that are found in residential light switches, for example. The yield in silver is well below the weight of the contact, but they are well worth processing. 

I always used tap water for these processes. While a little silver chloride is generated, it was eventually recovered when my waste materials were processed by furnace. You may prefer to use distilled water, but it's not necessary as long as you don't discard anything. 

Hope I covered the important things. Please ask if I did not.

Harold


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## Fever (Apr 1, 2007)

Thanks for the great info Harold!

When you say that you doubt they are just plated, do you think they may be solid? There are no "tabs" or "discs" of soldered-on contacts with these. They are solid through and through. That's why I thought they might be solid silver. These are WW2-era contacts, and US Military at that. They rarely spared any expense.

So the reverse electroplate technique that works so well for Lazersteve would also work well if these were indeed silver plated? No differences in the chemicals/ratios/materials? How about differences in the reaction itself? Would it stop fizzing when the plating is stripped, as in Steve's vids?

Also, which one of these things is a "Buss"? As I mentioned, there are no soldered-on tabs or anything else.

I think I'll cut one of these in half on my band saw and see if they are indeed plated or not. I'll let you all know, then hopefully I can proceed to refine these into high-grade silver.

Thanks again..... Fever


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## Harold_V (Apr 2, 2007)

Fever said:


> Thanks for the great info Harold!
> 
> When you say that you doubt they are just plated, do you think they may be solid? There are no "tabs" or "discs" of soldered-on contacts with these. They are solid through and through. That's why I thought they might be solid silver. These are WW2-era contacts, and US Military at that. They rarely spared any expense.



Considering the era, you may be right. I recall making some silver contacts from coin silver as a young apprentice when I worked in the missile industry. All of my experience with contacts came in the 80's and early 90's, all from industrial scrap. One salvage yard used to send me contacts to refine on a somewhat regular basis. In that case, they were always soldered to a base piece, almost always pure copper, and about half the time silver plated after assembly. Makes them look better after the soldering operation. 



> So the reverse electroplate technique that works so well for Lazersteve would also work well if these were indeed silver plated? No differences in the chemicals/ratios/materials? How about differences in the reaction itself? Would it stop fizzing when the plating is stripped, as in Steve's vids?



Because I rarely processed electronic scrap, and almost never anything plated, I am not wise in the way of running a stripping cell such as these. I do happen to have the patent number, thanks to another contributor, and it details the matters of importance. I highly recommend you read the original patent, number 2185858, issued in 1940 to S.R. Mason. It will help you understand the parameters, and what to expect. Also, the contributor has given some excellent information regards running these cells. so combined with Steve's guidance, you should come to a firm understanding of how to go about stripping silver. I'm sorry I don't have the proper thread in mind, but look for posts by *goldsilverpro*. He's very experienced in this field and has posted some great information. Unlike the majority of us here, he has worked in the refining industry since a young man, and he's no kid!  Better yet, he's helpful, unlike others that claim to have experience. 



> Also, which one of these things is a "Buss"? As I mentioned, there are no soldered-on tabs or anything else.



It's entirely possible that there is no copper involved. The buss would be the distribution portion of the circuit, to which the contact was attached. In this case, you may be right that it is just a solid piece of silver but your comments, below are what I'd recommend:



> I think I'll cut one of these in half on my band saw and see if they are indeed plated or not. I'll let you all know, then hopefully I can proceed to refine these into high-grade silver.




Do that, then touch the cut faces with a drop of nitric. If they're silver, you won't get a color reaction, although the silver itself will take on a sort of cream color after a moment or two. Allowed to sit long enough, and the silver is an alloy of copper, you'll eventually see a little blue, too. If they're copper, or a light yellow allow, you'll get a copper (blue) reaction from the acid, almost immediately. I mention this because a saw cut can be deceiving. The soft surface metal is often dragged across the face of the cut, disguising the base metal. 

Are you familiar with the solution that is used to test for the presence of silver? It's really easy to make, and easier to use. A drop, applied by a test bottle with a dobber, instantly turns blood red on silver------and only silver. If you'd like the information needed to make the solution, please ask and I'll try to find my notes. You'll need some reagent nitric, distilled water and potassium dichromate. Make a couple fluid ounces and you'll have enough to last you for a couple years, maybe more. You can buy a kit from jewelry supply houses, everything but the nitric, and depending on the kit chosen, you may also get test needles and a touch stone for determining the purity of karat gold. 

Harold


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## Fever (Apr 3, 2007)

Outstanding information Harold! Thanks!

I will try and bring one of these into work tomorrow and slice it, file it, and scruntinize it to determine its composition. I'll then hit it with a drop of Nitric and see what happens. My fingers are crossed that this stuff is solid Ag. If they are, I'm sitting on a few hundred ounces! I would also think the military would opt for a higher purity in their contacts than in other civilian applications, so maybe this stuff is the real deal. We'll see....

Thanks again for the detailed info. I appreciate your efforts!

Fever


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## Fever (Apr 3, 2007)

:roll:  :roll: 

PLATED!

Totally deflated today, after sawing into these giant contacts. They are indeed plated! Oh well, if I can figure out the best method to strip this silver plating effectively, I should still have a good bit of pure silver to refine. 

Looks like I'll have to look into that patent you mentioned Harold. I'll have to find the right way to do these for maximum yield.

Fever


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## Harold_V (Apr 4, 2007)

Fever said:


> :roll:  :roll:
> 
> PLATED!
> 
> ...



Rats! Sorry to hear it, but then I'm not surprised, either. While the "gummint" spends a ton of money, it's not _always_ on foolish things. Could be that the contacts, as designed, were more than adequate, with no need for silver. Guess we'll never know!

Anyway, the patent is nothing more than the one that covers the same stripping cells all these guys are using to reclaim gold--perhaps with minor alterations. Regardless, check out the patent, which will give you an understanding of the proper requirements. 

Do keep one thing in mind. If you get involved with silver processing, you can use the entire contact for silver recovery. Not suggesting for even one moment that stripping them is a bad idea, especially if you use them as a learning curve, but if you never build a cell, you can still recover the values simply by using the copper as noted. 

Luck! And keep us all posted. 

Harold


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## Fever (Apr 4, 2007)

I definitely will Harold, and thanks again for all the info!

Fever


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