# Extruded silver bar.



## justinhcase (Oct 20, 2015)

I received a lot of what test's as silver but digest's a bit unusually.
It dissolves away but leaves a slight coating that seems to retard digestion.
The coating rub's right off easily to reveal silver again and will digest a new layer.
When it finally decided to digest it went quite quickly as if a tipping point had been reached.
It produced a yellow to orange coloration in solution and gave a very good percipient with hydroelectric acid was added.
I have a number of people who work with silver and as this is such clean stock I was thinking of selling it straight on.
Has any one seen stock like this and if so where was it used and what was the alloy meant for.
Regards
Justin


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## Palladium (Oct 20, 2015)

Is the coating that forms white and looks like silver chloride?


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## justinhcase (Oct 20, 2015)

Palladium said:


> Is the coating that forms white and looks like silver chloride?


Yes it is very similar.
So I checked my acid and used new stock.
The coating dissolves eventually and give's the solution that orange color??


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## Palladium (Oct 20, 2015)

I would guess that it was tin. Tin will passivate the surface of the silver and stop the penetration of nitric acid just like silver passivates the surface of gold creating silver oxide. The higher the tin content the greater the passivation effect. Heat is your friend and with higher contents of tin, because it will break through faster with higher heat. I run a lot of silver brazing alloys and tin can be a pain in the arse. Believe it or not though i like the higher tin content stuff more than the lower tin stuff. The reason being is the low tin alloys leave a fine silty residue that is hard as heck to filter because of the crystalline size. The higher tin stuff forms larger granules that are easy to filter. Butttttttt...... The washing of the residues are more difficult. I boil my residues in a stainless pot to free up any trapped silver nitrate. After the water boil the tin filters incredibly easy!


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## 4metals (Oct 20, 2015)

That appears to be an anode. The silver is extruded and the "barbell" shape maintains the surface area of the anode longer in the bath as the edges always dissolve away first. I know a company that manufactures that type of silver anode material, they said it's cast from .999+ oxygen free silver.


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## justinhcase (Oct 20, 2015)

4metals said:


> That appears to be an anode. The silver is extruded and the "barbell" shape maintains the surface area of the anode longer in the bath as the edges always dissolve away first. I know a company that manufactures that type of silver anode material, they said it's cast from .999+ oxygen free silver.


Would Oxygen free silver take slightly longer to digest than my own silver crystal's?
The digestion seemed to lock more NO2 into the solution than usual and kept the solution orange right the way through reduction,once I evaporated it down to crystal I got a good clean crystal.
If any would like to trade I have a good supply.
Thanks for all your input,i very much appreciate all the help you chaps give.
J


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## 4metals (Oct 20, 2015)

Oxygen free silver should be elemental silver as pure as it gets. What I have been told at the client who makes the anodes is that they make silver anodes, only silver anodes and the rolling mills can only be contaminated with silver. 

Other anode manufacturers make the same barbell configured anodes in silver, tin, cadmium and a few other mixtures (alballoy (Cu,Sn,Zn) is one). It is possible for the metal to gall when running through the mill if it goes too fast or is made too thin too quickly. Never an issue for the guys I spoke to because they only do silver, but if the same mills are used for different alloys the galling and leaving residue of contamination on the surface is real.


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