# Pot loss



## mikeinkaty (Feb 4, 2013)

Dividing the weight of all the bars poured from the melted crystals by the total weight of all crystals collected from my cells shows that I have a 1.8% loss in weight. Is this typical for torch melting? Any tips on how to minimize pot loss?

Mike


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## butcher (Feb 4, 2013)

The crystals may hold water or sometimes acids (depending on what type of metal crystals, or metal salts are melted), this may account for lose of weight, I am not sure that is the case with what you are experiencing.


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## lazersteve (Feb 4, 2013)

Another source of melt loss with silver, aside from moisture, is excessive melt temperature. Silver metal has a fairly low heat of vaporization as metals go and can be 'boiled off' without accurate temperature control when melting. This volatility means that a torch is not the best choice for melting refined silver. It's best to melt silver with a furnace that has an accurate temperature gauge to avoid losses due to vaporization. If you are going to torch melt use a lower temperature gas like propane. Silver chloride is another source of melt loss with silver from incomplete conversions. Silver chloride vapors are much thicker than silver metal vapors and have a salty odor.

Evidence of silver vaporization reports as a dull gray to bright white halo around the dish and even on the torch tip. You may even see white wisps rising from the melt while it is molten. In cases of extreme over temperature of the melt, the silver may boil and tiny BB's of silver will condense around the cooler portions of the dish.

Avoid breathing any metal vapors as they can be hazardous to your health. Always melt with a good ventilating hood or strong fan at your back pointed up and away towards open air. Position the fan so it does not blow directly into the melting dish, but instead blows up from below the firebrick hearth with you positioned between the fan and the melt. You should be able to turn your head and breath fresh air if the need arises. The fumes should all be moving up and away from the melting area.

Steve


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## mikeinkaty (Feb 4, 2013)

lazersteve said:


> Another source of melt loss with silver, aside from moisture, is excessive melt temperature. Silver metal has a fairly low heat of vaporization as metals go and can be 'boiled off' without accurate temperature control when melting. This volatility means that a torch is not the best choice for melting refined silver. It's best to melt silver with a furnace that has an accurate temperature gauge to avoid losses due to vaporization. If you are going to torch melt use a lower temperature gas like propane. Silver chloride is another source of melt loss with silver from incomplete conversions. Silver chloride vapors are much thicker than silver metal vapors and have a salty odor.
> 
> Evidence of silver vaporization reports as a dull gray to bright white halo around the dish and even on the torch tip. You may even see white wisps rising from the melt while it is molten. In cases of extreme over temperature of the melt, the silver may boil and tiny BB's of silver will condense around the cooler portions of the dish.
> 
> ...


Overheating is what I thought. But, with ox/ac I can line up my cups and pour 8 or 10 bars in pretty short order. I don't know if I'd be able to afford a kiln that would give me that speed. I always have the shop door open and do the pouring right by the door. I guess I need to determine how much more of this I want to do. My initial goal has been 200 ozs and I'm about there.
Mike


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## Bushka (Feb 11, 2013)

mikeinkaty said:


> Overheating is what I thought. But, with ox/ac I can line up my cups and pour 8 or 10 bars in pretty short order. I don't know if I'd be able to afford a kiln that would give me that speed. I always have the shop door open and do the pouring right by the door. I guess I need to determine how much more of this I want to do. My initial goal has been 200 ozs and I'm about there.
> Mike



Just wondering... Where do you guys find all this sterling at such a price that it is profitable to refine it? Also, can't you get about the same price from a refiner for just the sterling without doing anything to it?

Dan


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## Lou (Feb 11, 2013)

I always pay a higher price for fine silver (especially silver crystal).

I guess most refiners will pay what they can get away with on material.


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