Foreign Substance

JeffMTampa

I recently purchased a very nice 1909 Barber Dime in AU condition with some sort of a foreign substance on the obverse. It appears white to the naked eye in an arcing fashion. Perhaps the foreign substance was deposited with another dime shielding the coin? Does anyone have an idea what the substance is? I tried an acetone and then a vinegar soak to remove it with no success,

I had a Morgan Dollar years ago with a similar residue; I sent it to NGC for conservation, the residue was removed, and the coin straight graded. My guess is the residue will come off easy if I knew what it was.

amwldcoin

Looks like something has etched the surface.

JeffMTampa

@amwldcoin said:
Looks like something has etched the surface.

No, there's a "powdery" looking substance on the coins surface. It looks like zinc? I've seen it before, but what is it?

amwldcoin

Silver Oxide would be my guess!

@JeffMTampa said:

@amwldcoin said:
Looks like something has etched the surface.

No, there's a "powdery" looking substance on the coins surface. It looks like zinc? I've seen it before, but what is it?

Treashunt

I don't see a foreign substance, I do see a die clash.

ldhair

The black spots make me think it's from a bad dip.

JeffMTampa

@Treashunt said:
I don't see a foreign substance, I do see a die clash.

There is a very distinct die clash, but the "substance" is brownish in color in an arc through "Liberty".

Darrels guess of Silve Oxide seems promising; I'll check it out.

BillJones

I think he is talking about the small black streaks. I think that they might be impurities that were in the metal when the coin was struck. There is nothing wrong with them per say. Some collectors might wish that they weren't there.

TPRC

@amwldcoin said:
Silver Oxide would be my guess!

@JeffMTampa said:

@amwldcoin said:
Looks like something has etched the surface.

No, there's a "powdery" looking substance on the coins surface. It looks like zinc? I've seen it before, but what is it?

Whatever it is, it looks like it's not coming off easily. Good luck with that and let us know how it turns out.

BillJones

@TPRC said:

@amwldcoin said:
Silver Oxide would be my guess!

@JeffMTampa said:

@amwldcoin said:
Looks like something has etched the surface.

No, there's a "powdery" looking substance on the coins surface. It looks like zinc? I've seen it before, but what is it?

Whatever it is, it looks like it's not coming off easily. Good luck with that and let us know how it turns out.

I don't think that "off" is the right term from those marks. I believe that the word "in" might be more accurate. To remove those marks, you would have to get below the surface, which is not a good thing to do. It is best left alone. They really don't amount to much, and as the coin tones over time, they will become less obvious.

ms70

Try an acetone dip. Maybe it will be easier (and less expensive) than you think.

ricko

I tend to agree with Bill... a harsh dip would likely remove much of it, however, I do not think you would like what remains. Cheers, RickO

JeffMTampa

I had a Morgan Dollar a few years back with a very similar substance on it. "On" is the opertative word. I tried dipping that coin with no effect. NGC removed it without a problem. My guess this is the same thing, but what to put on it?

Stork

Xylene?

Insider2

@BillJones said: "I think he is talking about the small black streaks."

No Bill, he is talking about the dull gray ARCHED stain that has ETCHED the surface. I apologize for not knowing its chemical name (perhaps silver oxide?). I have heard them called "dip burn" by numismatists who conserve coins. I'll bet the black stains you referred to will turn the same color if the coin is dipped.

Summary. The surface of the silver became tarnished (corroded) due to contact with something. It darkened and when the coin was dipped, only the etched, gray surface remained.

BTW Those Proof Seated dollars and Proof Trade dollars with a similar, entirely gray surface suffered the same fate after being dipped to remove toning.

erwindoc

How about a bit of MS70 on it? Rolled on gently with a q-tip shouldnt hurt it.

Insider2

Terminal corrosion! Sorry.