Melting impure silver causes a lot of spluttering.

[Yggdrasil]

Try using a HCL wash.

What about directing your reply to the OP?

 

[Amol Gupta]

Do you suspect Palladium as "impurity"? I have not molten it in a furnace but when using an propane/butane-oxygen flame I have had problems with the Pd sputtering around...

My xrf does not suggest it but then again xrf only takes you so far

 

[Amol Gupta]

Try using a HCL wash.

I'm not sure how that would help, what is it that we are trying to romove here....?

 

[slsmp40]

I do admit I have moisture in my melt, but I'm not sure why is it only there in the impure melt, my clean cement silver 98-99% does not exhibit such explosions.

Zinc will sputter and pop with a white offgas of zinc oxide if it is happening when you are up to temp. Common if you cement with zinc powder or any scrap copper that happens to be a brass alloy.

 

[Amol Gupta]

Yes, molten silver readily absorbs oxygen from the air, a phenomenon known as "spitting of silver" where the absorbed oxygen is released violently as the silver solidifies, causing small silver particles to be ejected; this is why precautions are often taken when working with molten silver to prevent this issue.

Key points about molten silver and oxygen absorption:

• Significant absorption:
  Molten silver can absorb a large volume of oxygen, sometimes up to 20 times its own volume.
  
  
• Cooling release:
  When the molten silver cools and solidifies, the absorbed oxygen is released rapidly, causing the "spitting" effect.
  
  
• Prevention methods:
  To mitigate spitting, I use a sealed furnace for my melts to help prevent oxygen absorption. I've read you can use a thin layer of charcoal on the molten silver, but I've never tried it.

What you are saying makes a lot of sense and I've heard of adding charcoal to cover the melt, but I guess you misunderstood me the sputtering happens as the metal is in liquid state(during the melt process) and not when the metal is solidifying.

I'm not sure if this is some wild theory but I'm performing my melt in a graphite crucible so there is every possible chance of the absorbed oxygen reducing to carbon-di-oxide and being released. I'm not really sure if this is consistent with my observation.

A couple of observations that might be helpful.
1. The sputtering stops after some time and the molten metal sits stable.
2. The sputtering is more if my silver is impure, close to 80%.

 

[Amol Gupta]

Zinc will sputter and pop with a white offgas of zinc oxide if it is happening when you are up to temp. Common if you cement with zinc powder or any scrap copper that happens to be a brass alloy.

I'm pretty sure this is not zinc, I cemented out my silver on pure copper.

 

[Amol Gupta]

Here a theory I'd like you guys to listen.

The cement silver I melted was exposed to air for a few days which had turned black(formation of some oxides is my best guess), boiling with hot water has black residue being washed away but the cement silver was still black, as I was melting, these oxides might be releasing oxygen as they were being reduced back to metalic state, which I guess was causing the sputtering during the initial melting stage and was fairly stable after some time.

 

[Yggdrasil]

Here a theory I'd like you guys to listen.

The cement silver I melted was exposed to air for a few days which had turned black(formation of some oxides is my best guess), boiling with hot water has black residue being washed away but the cement silver was still black, as I was melting, these oxides might be releasing oxygen as they were being reduced back to metalic state, which I guess was causing the sputtering during the initial melting stage and was fairly stable after some time.

The Silver should not turn black in the matter of days, unless it still have acid present and other impurities.
Try washing it more.

 

[Amol Gupta]

The Silver should not turn black in the matter of days, unless it still have acid present and other impurities.
Try washing it more.

Not proper washing and it came to bite me back.
I got impure silver as I melted it I'll have to dissolve it back and reprecipitate.