# Silver cementing while digesting



## Cozza (Apr 7, 2019)

G'day all,
This is my first post so please be gentle!
As a quick preface, I have just finished my first run of 13ozt of silver from start to finish and am most pleased with the resulting crystal!
Anyways today i went to a local flea market looking for Corning ware and silver. I found a nice old bangle that looks to be made from an old piece of sterling chain. There were no hallmarks but $2 for a 36grm item was a good gamble. I tested it when i got home and is indeed silver. It has been digesting in nitric all day, and when checking on it just now there is some material floating around in the beaker that I swear is cement silver. The only thing I have done different this time was that I diluted the nitric with rinse water from a prior batch of cement silver. It had also been filtered prior to re use and the bangle was also incinerated before digestion.
Does anyone have any insights as to what this floater material might be?
Cheers,
Cory


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## FrugalRefiner (Apr 7, 2019)

How much nitric have you used?

Dave


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## kurtak (Apr 7, 2019)

It is a good possibility it Rh (Rhodium) 

It's not uncommon for sterling jewelry to be plated with Rh

The Rh plating gives the jewelry a bright (silver) mirror like luster & prevents the silver from tarnishing

The Rh plating is usually VARY thin & when the silver is dissolved the Rd plating remain behind as VARY fine flakes - much like the vary fine flakes left behind from ENIG gold plating

In other words - it appears as a silvery dust & because it is so thin & light weight it tends to float 

Kurt


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## Cozza (Apr 7, 2019)

Thanks for the replies Frugal and Kurt.
An update now, it seems it was not silver after all. Last night the reaction had stopped so I filtered off most of the solution making sure to leave the cement looking material and remains of the bangle in the beaker. The first nitric treatment was approx 36ml with the same of used distilled water. I added another 10ml of each to finish the digestion and the mystery stuff went into solution.
Now I diluted the filtered solution and added copper and there was very little cementing reaction. This morning there is some cement present but no where near what it should be if it were a solid silver item.
I'm not discouraged by this situation, this is a great learning experience for me. Now how do I work out what the heck I have?
A few more details on how the item responded- the solution after digestion is exactly the same blue / green as the other sterling I have done. The item was a consistantly light grey colour all the way through digestion , ruling out copper with silver plating. 
So how does on go about identifying this mystery metal now?


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## Platdigger (Apr 8, 2019)

I am curious if it could have been silver plated "nickel silver"?
Nickel silver or German silver contains no silver by the way.


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## Cozza (Apr 8, 2019)

I've worked with enough nickle during my time making and restoring bagpipes to rule it out. I've now placed some iron in the solution to see if anything drops out.


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## FrugalRefiner (Apr 8, 2019)

Why iron? I expect just about everything will cement out. Copper would have been a better choice, as it will only cement precious metals and mercury if present.

Dave


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## kurtak (Apr 8, 2019)

Nickel silver/German silver is mostly copper - the nickel in the alloy "bleaches" the copper changing the color of copper from its copper red appearance to a "near" silver white appearance

https://en.wikipedia.org/wiki/Nickel_silver

If cementing with copper did not cement out any real amount of silver then Platdigger is probably spot on - it was probably "silver plated" nickel silver

DMG test for nickel (of the solution) would be the way to confirm that

Kurt


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## rickzeien (Apr 8, 2019)

This is another great thread. I am constantly amazed at how deep the knowledge base is. Thanks to all for letting me "look over your shoulder"

Sent from my LG-H872 using Tapatalk


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## kurtak (Apr 8, 2019)

FrugalRefiner said:


> Why iron? I expect just about everything will cement out. Copper would have been a better choice, as it will only cement precious metals and mercury if present.
> 
> Dave



Dave - he already tried cementing with copper - copper did not cement any real amount of silver out

Kurt


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## kurtak (Apr 8, 2019)

rickzeien said:


> This is another great thread. I am constantly amazed at how deep the knowledge base is. Thanks to all for letting me "look over your shoulder"
> 
> Sent from my LG-H872 using Tapatalk




Rick - per the underlined --- THANKS for letting us look over your shoulder on the furnace build :mrgreen: 

I can't wait to see the "first pour" on that "bad boy" 8) (yes I am keeping an eye on that thread)  

Kurt


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## FrugalRefiner (Apr 8, 2019)

kurtak said:


> FrugalRefiner said:
> 
> 
> > Why iron? I expect just about everything will cement out. Copper would have been a better choice, as it will only cement precious metals and mercury if present.
> ...


Thanks Kurt. I guess I read that yesterday, then had a senior moment.  

Dave


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## Cozza (Apr 8, 2019)

Great replying fellows!
I went to iron as 24hrs with cu did not cement anything but a small amount of possibly silver.
Now the iron has some interesting stuff on it thismorning. There seems to be no visible copper on it, rather some interesting dark blue almost black Crystal's. I will try a post a photo shortly.
This is turning into a great learning exercise!


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## Cozza (Apr 8, 2019)

My eyes must be failing!
Upon closer inspection there is a small amount of copper under the dark material.


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## kurtak (Apr 9, 2019)

That's because your not cementing only the copper when cementing with iron/steel

iron (or steel) cements "anything" below iron in the reactive series 

https://en.wikipedia.org/wiki/Reactivity_series

so if you dissolved nickel silver - then iron cements not just copper but a combination of nickel & copper

Kurt


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## Palladium (Apr 9, 2019)

Take some of the solution and add a chloride ion such as salt or hcl.
If you see the test solution get cloudy or white then you can confirm that you have silver in solution. You can use this test like stannous chloride to confirm the presence of silver.


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