# Optimizing pouring of gold and silver bullion bars



## Traderdoc (Jul 19, 2021)

Hi there

I have also placed this message in the silver thread.

I'm wondering if anyone is able to help. The knowledge that I've seen on this forum is startling so I'm sure some experts on here might have some idea of what I have.

I've just started the very fascinating hobby of pouring gold and silver bars. I have done a number of silver bars so far but have noticed this white "staining" on the top of all. My bars. I'm melting the metal in graphite crucible so was thinking that it might be graphite dust that has settled on the top.

In order to try and get this staining off the bars I placed them in a rotary tumbler for 24 hours. It didn't make much difference and the staining is still there ( see 2 attached images).
Anyone know what this is, how I can get rid of it and how I can prevent or lessen it in my future pours?

Thanks so much for any insight.

TD.


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## Hartbar (Jul 19, 2021)

I’m far from an expert on this, but on the top bar it looks like flux from your melting dish carrying over with the molten silver into ingot. Borax or Boric acid. I glaze my ceramic melting dishes with borax and have had same problem. I put the bars that have flux on them in warm sparex jewelers pickle for a couple of hours, it normally works it off. The bottom bar looks like you have impurities in your silver.
What’s your process for refining?


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## Traderdoc (Jul 19, 2021)

Thanks for the reply.

I actually don’t use any flux when I melt my metal. I just melt it directly in the graphite crucible.
I haven’t yet tried to delve into the refining side - I am purchasing what I’m told is .999 silver from a large refinery.
Is there a possibility that the refiners might have some contamination of the metal they supply? Is this a common issue with commercial refineries?
I’m hoping that’s not the case as I have struggled for many months to find a refinery in Canada who would supply me smaller amounts (around 50 to 100 ounces at a time) at a reasonable price.

Don’t quite know what I should do next?


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## FrugalRefiner (Jul 19, 2021)

So, what is your purpose?

If you're buying 999 silver from a large refinery, what value are you adding that provides you a means for a profit? Perhaps I'm just missing something. My apologies if I am.

Dave


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## Traderdoc (Jul 20, 2021)

I've watched a number of individuals online pouring Silver and because I've been a precious metal stacker since 2000 I thought it would be great to see what producing bars from shot or scrap would be like. I'm always up for a challenge and pouring metals seems to be quite a challenge technically. I would like to add totally unique bars to my collection. 
In time, f I get good enough, I might consider selling them if there was a market - when precious metal prices are a lot higher from where they are currently.


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## 4metals (Apr 8, 2022)

What precautions do you take to protect the molten silver from absorbing oxygen from the air? What you see is likely the silver “erupting” to expel the oxygen as it cools. It is not actually that bad so you may be already taking some precautions. The photo below shows silver bars cast taking no precautions to keep the silver from absorbing oxygen, as you can see it can get a rather pocked porous look if no precautions are taken. 
Describe your melt setup and what you do to pour the silver and possibly with more detail we can help you.


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## Traderdoc (May 2, 2022)

I don’t usually take any precautions as I don’t really know what precautions to take. Lou, one of the very knowledgeable moderators suggested throwing a piece of beeswax on the top of the melt to prevent oxidation. I will be trying this with my next pour.


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## 4metals (May 4, 2022)

Beeswax? now that's an organic approach I,ve never heard of!

Most shops burn a reducing flame over the crucible, starting before the metal starts to melt and continuing through the pour. Larger shops who do a lot of melting also keep a flame over the crucible during the pour and over the mold they pour into. 

By keeping the flame over the melt all of the oxygen in the air is consumed by the oxygen starved flame so nothing remains for the molten silver to absorb.


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