Pancake Coins or Encrusted Coins

[bdahunter]

I think it was KellycoChick who asked me to explain a comment I made about pancake coins. I tried to explain it in words but they say a picture is worth a thousand words so here's a couple of thousand words. This isn't the best example I've found but it's the only on I've found lately. The pics are of a 1949 .500 silver, British 1 Shilling coin, King George VI. It's the black silver oxide that gives away the fact that you've found an older silver coin that has been in the water for a good while.

Cheers,

BDA

PS the clad quarter in the first pic was found in the same bay as the silver shilling, note the difference in the corrosion, clad just doesn't build encrustation the way silver does

[Buster]

We get the greens here in Florida also..The sand and the water tears them bad....Buster...

[johnj45586]

Most of the stuff I find hasn't been in the saltwater/sand long by the standards you are talking about. My stuff is usually from this year with a few pieces a little older.
I have found silver rings that have a black stain that either cannot be removed or has heavy pitting when it is. I haven't had any silver or clad really encrusted.
But pennies are a different story. A lot of times the encrustation can be as much as inches. When it is removed there is very little left of the penny. Zinc pennies are the absolute worst.
How do you remove the encrustation from silver? I would guess electrolysis. Hopefully I will find some old silver coins one of these days. There is quite a bit of history around Southern California.
Happy hunting

[bdahunter]

Originally Posted by johnj45586

Most of the stuff I find hasn't been in the saltwater/sand long by the standards you are talking about. My stuff is usually from this year with a few pieces a little older.
I have found silver rings that have a black stain that either cannot be removed or has heavy pitting when it is. I haven't had any silver or clad really encrusted.
But pennies are a different story. A lot of times the encrustation can be as much as inches. When it is removed there is very little left of the penny. Zinc pennies are the absolute worst.
How do you remove the encrustation from silver? I would guess electrolysis. Hopefully I will find some old silver coins one of these days. There is quite a bit of history around Southern California.
Happy hunting

Some of my finds have been in the ocean a considerable amount of time, John. Ocean salinity is slightly higher in Bermuda due to our proximity to the Sargasso Sea and the low exchange of sea water across the reef surrounding Bermuda vs evaporation. The result is heavily oxidized finds. I'm not a fan of electrolysis because it causes even more serious pitting to a find that has already been oxidized. Electrolysis causes the build up of hydrogen sulfide gas between the silver and the silver oxide build up surrounding the silver, the gas separates the silver oxide from the silver but more silver is lost in the process. It is too easy, in my opinion to over do it with electrolysis and wind up cooking the find.
I prefer to use a lemon juice (any acid would do but citric acid is milder and cheaper) to immerse the find and I pour half a teaspoon of regular table salt over top of the find. The chemical reaction between the acid (lemon juice) and the basic (salt) causes the formation of hydrogen sulfide gas on a lower level than that caused through electrolysis. The acid also works at breaking down the silver oxide build up which assists in the process without harming the find nearly so much as electrolysis.
A good mechanical cleaning before(if the find is really bad) and after results in a nice clean find with a minimum of additional damage.
ZLincolns I just junk, they're not worth the hassle to me.

Cheers,

BDA

[jimmyjiver]

Hi, Everything You Ever Wanted To Know About Encrustation Was In That Post. I'd Try A Nut Cracker On The Tough Ones. Thanks For Sharing ...JJ

[johnj45586]

Originally Posted by bdahunter

I prefer to use a lemon juice (any acid would do but citric acid is milder and cheaper) to immerse the find and I pour half a teaspoon of regular table salt over top of the find. The chemical reaction between the acid (lemon juice) and the basic (salt) causes the formation of hydrogen sulfide gas on a lower level than that caused through electrolysis. The acid also works at breaking down the silver oxide build up which assists in the process without harming the find nearly so much as electrolysis.
A good mechanical cleaning before(if the find is really bad) and after results in a nice clean find with a minimum of additional damage.
ZLincolns I just junk, they're not worth the hassle to me.

Cheers,

BDA

Thanks for the info. I will give that a try. I don't have but a few pieces that were a problem. I didn't really want to get into electrolysis.
I can't bear to junk anything I found, so I have one coffee can now almost full of bad zinc pennies (with some nickels, dimes and quarters that are mashed, bent or sandblasted away). Maybe I can make a boat anchor when I fill a couple more.