All,
I wanted to share the progress of my recent ventures into refining some sterling silver that I had purchased.
The item I experimented on was an old solid sterling silver bowl that I acquired from a lady who had inherited it from her mothers collection. Here's how the bowl looked the day I purchased it last week:
The bowl weighed 25.2 oz (713 g). I cut the bowl into pieces and melted it down into a bar slightly smaller than a US dollar bill and almost 1/4" thick.
I processed the sterling bar using electricity (12V 10A battery charger) and and electrolyte of left over copper nitrate from previous inquartations and cementing reactions(see on my website).
I initially used a copper mesh cathode (negative lead) and when the copper level dropped, I switched to a hard graphite block (2" x 4" x 1/2"). With both cathodes the copper built up as a heavy moss on the cathode and was periodically scraped into a Tupperware dish for further cleaning. As the copper levels dropped silver was co-deposited with the copper onto the cathode. The silver tends to accumulate on the back side of the cathode and the copper on the front.
The solution became more and more saturated with silver nitrate as the experiment went on. Here's is a photo of the partially dissolved anode (left), the cleaned silver powder (center), and a 52.2 gram test melt of the resulting purified silver (bottom left) with a U.S. quarter for size reference(bottom right):
As you can see the purified silver is much finer than the original piece and the anode bar. The surface of the silver button is crabby indicating good purity. The button will now be run through a Thum cell to remove the last traces of impurities.
I plan on posting a video of this process when time permits. As you can see, the bar still has some ways to go before it is completely processed. The bar in the photo has been in the cell for 10 hours. I ran the cell for 2 hours per day for the last five days to get to this point.
More to come...
Steve
I wanted to share the progress of my recent ventures into refining some sterling silver that I had purchased.
The item I experimented on was an old solid sterling silver bowl that I acquired from a lady who had inherited it from her mothers collection. Here's how the bowl looked the day I purchased it last week:
The bowl weighed 25.2 oz (713 g). I cut the bowl into pieces and melted it down into a bar slightly smaller than a US dollar bill and almost 1/4" thick.
I processed the sterling bar using electricity (12V 10A battery charger) and and electrolyte of left over copper nitrate from previous inquartations and cementing reactions(see on my website).
I initially used a copper mesh cathode (negative lead) and when the copper level dropped, I switched to a hard graphite block (2" x 4" x 1/2"). With both cathodes the copper built up as a heavy moss on the cathode and was periodically scraped into a Tupperware dish for further cleaning. As the copper levels dropped silver was co-deposited with the copper onto the cathode. The silver tends to accumulate on the back side of the cathode and the copper on the front.
The solution became more and more saturated with silver nitrate as the experiment went on. Here's is a photo of the partially dissolved anode (left), the cleaned silver powder (center), and a 52.2 gram test melt of the resulting purified silver (bottom left) with a U.S. quarter for size reference(bottom right):
As you can see the purified silver is much finer than the original piece and the anode bar. The surface of the silver button is crabby indicating good purity. The button will now be run through a Thum cell to remove the last traces of impurities.
I plan on posting a video of this process when time permits. As you can see, the bar still has some ways to go before it is completely processed. The bar in the photo has been in the cell for 10 hours. I ran the cell for 2 hours per day for the last five days to get to this point.
More to come...
Steve
