I have many questions Asks:
How to restore shine to a copper coin dulled by acid and did I use to much acid
I found an old copper 1 cent coin of all places, outside on the asphalt road one day. On the tail side, though a little dirty, it had some shine and you can see the coin value, the other side was completely covered in black gunk. It is pretty old and rare so I wanted to clean it.
Since acidic substances remove copper oxide, I put the coin in a bottle cap with about 3mls of black vinegar as that was the only type of vinegar I had access to.
Here's my problem though, I think I may have done more damage than good. Rather than leaving it in for 1 or even 5 minutes (which I now see is the recommended time), I left it in for several hours (5-6 hours, 2-3 each time) because that's how long I used to keep oxidised coins (albeit not copper) and screws. Afterwards, I flipped it over to repeat the process because the side touching the bottom of the cap (the blackened head side) had less exposure to the vinegar during the first soak, and was less clean than the top tail side. Then I realised the penny is not shiny at all anymore like it used to be - the tail side is clean, against recommendations I cleaned the heads side with a paper towel which removed some but not all of the blackened gunk, but the penny is not shiny and it seems that some of the few remaining details on the tail side was worn away from being left in the vinegar too long. I am not sure if the details were actually worn away or if the details were just easier to distinguish before I cleaned it because of the dust in the crevices.
No, the coin has not turned green.
My question now is, how can I at least restore shine to the coin? (I read that olive oil, but not virgin olive oil, can be used to do so, but I am not sure what kind of oil we have so didn't use it). How can I finish cleaning it non-destructively?
Thank you in advance.
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