Cleaning some salt water crust

rjsvt · March 24, 2015 1:12AM

I found these three crusty items on the NH coast a few days ago with my CTX 3030. Could see Washington's face on the quarter sized coin if held just right. I think the small one is a Mercury dime.

Started playing with the quarter first. Tried the ultrasonic jewelry cleaner for minutes, then hours, could not get any of the sandy crust to budge. Built my first electrolysis unit and tried that. Coin had oxidized pretty bad, and I was a little impatient. I left the alligator clip in the same place on the coin for too many cycles, and it ate away the edge. Turned out to be a 1963 D quarter.

Trying to clean the medal looking object now with a little more patience.

bob

Bayard1908 · March 24, 2015 1:55AM

I think I'd start out with a long soak in distilled water or white vinegar.

pcgs69 · March 24, 2015 5:35AM

For those cookie coins a swift hit with a spoon or similar object should easily break the crust. What's underneath is a different ball game. At least you're finding silver. Might try getting out this week....need to do some detecting!

rjsvt · March 24, 2015 11:03AM

I put the medallion object in the electrolysis bath for about thirty seconds and could see some bare metal on the edge where the clip was connected. Moved the alligator clip, another thirty seconds and more bare metal. I decided to just soak it in hot water for the day. Eventually, enough of the sand loosened up so I could see it's a Pope Paul VI medallion, brass I think.

Decided to soak the dime sized object in vinegar. It was bubbling a tiny bit, loosened a little dirt. After an hour, the crust still seemed hard. Rinsed it, then tapped it on the edge with a spoon. It cracked, and I ended up with a very thin 1912 Barber dime and two crusty silver-oxide pieces.

After all that, still not sure what I'll do next time I find a sea-crusted coin. The silver oxidizes and the process strips metal from the coin. The 1963 quarter wasn't as oxidized as the 1912 dime. But I damaged the quarter with the electrolysis by being too aggressive. Next time I will let it soak in hot water for a few days, keep changing the water, and see what happens. Hope to be heading back the beach soon.

bob

Bayard1908 · March 24, 2015 11:38AM

Fascinating finds. I hope your discover and perfect the best technique for cleaning them.

ricko · March 25, 2015 2:03AM

Sometimes acetone will help on salt water crust...not always. Vinegar is good.... I would first let it dry completely (several days), then tap it with a small hammer to loosen what you can. After that, soak in vinegar, tapping periodically. Heavily salt encrusted silver coins are rarely worth saving, except for the curiosity factor...Cheers, RickO

Cleaning some salt water crust

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