cleaning silver coin found on beach

[Moe (fl)]

I recently found a silver dime on the beach that came out silver gray. I cleaned it using the aluminum foil method (wrapped coin in foil) and put it in bowl with boiling water and 2 teaspoons of washing soda. After 10 minutes took the coin out and noticed that the grey was coming off but one side of the dime was covered with reddish stains. I was able to remove most of the reddish stains using a baking soda paste and a toothbrush. Is this common when cleaning beach silver coins with aluminum foil?

What are the reddish stains from? Is it the copper from the silver dime leaching out?

Thanks for the help.
- Moe

[wreckdiver1715]

Try using apple cider vinegar and aluminum foil, let it soak overnight.

[Moe (fl)]

Thanks Wreckdiver1715. Will the vinegar damage the coin or remove a layer of silver? I have heard that vinegar and salt are very strong and will remove too much metal.

[wreckdiver1715]

Overnight should just remove the most of the encrustation and should not damage the coin in any way as long as the coin does not come in direct contact with the aluminum foil. be sure to rinse the coin in fresh water afterwords. This process is called galvanic reduction, and is the method I use on all my clad coin finds that require some cleaning.

Tom

[Moe (fl)]

Do you use this method on silver coins found at the beach too or just clad? Do you dilute the vinegar with water?

HH.
Moe

[wreckdiver1715]

Primarily clad, but it depends on the condition of the silver coins. If the silver coin is heavily encrusted from spending the last few hundred years on the bottom of the sea, or buried in the sand I will use the electrolysis tank on it. Electrolysis will not work effectively on Clad coins, as it draws the copper into the silver, and will discolor the silver part of the coin. However, you can still use galvanic reduction on silver coins as well. I do not dilute the vinegar at all.
If there are multiple coins in a conglomerate, I will only soak them in fresh water, as these tend to fetch a higher value from collectors who want them as they were found. This is especially true if you are able to identify the history of how these particular coins came to be.

Tom