What will help this coin?

Beautiful coin minus the black gunk. What would you try to remove the gunk?

 

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Why not? Looks like tar or something organic. Try acetone or heptane (outside!!!) on one inconspicuous spot and see what happens. You might create a small shiny spot if the material's been on the coin for decades.

 

Melt it, purify the metal, then re-mint it. Easy.

 

thats a good idea

 

I know that PCGS and ANACS offer restoration services and will safely remove some of the gunk before grading. It's a really pretty coin, and it might be worth the cost, I'm not up on seated liberty rarities - I can't even tell you what the denomination of it is. Good luck with it!

 

Show us the back, please.

 

Assuming it's a dime (no half dimes minted, 25c and 50c had stars). Based on catalog value, restoration costs are out of the question...

 

I like the acetone idea. Give it a nice long bath. If its petroleum based gunk you should notice improvement. Worst that will happen is nothing.

 

It's a dime.

 

I can't remember the chemical someone said to use before you use acetone to remove any organic material. I think it started with a X or a Z.

 

I always thought it would be useful to examine spots like those under 50X -- you might even be able to identify the material at that power.

When the spot's as big as a dinner plate, you might get some very good clues on which solvents to use.

 

Most I have ever seen on 19th century coins, (all three metals), have been organic based if that helps. Seems to be some kind of black tar/oil from fingers mixing with dirt or something. Anyway, all coins like this I have bought over the years have dissolved with petroleum distillates like acetone. For some reason I had a batch of Peace dollars with this gunk once. I think I made three trips to the hardware store, since they only sold it by the quart.

 

Wonder if Amazon's cheaper? I'm buying more and more stuff by drone.

 

Acetone is the over-all go-to solvent. For really gummy tarry stuff toluene or xylene might work better. If you have any mineral spirit, you could try that, but then rinse it in acetone and allow to dry.

 

Yeah, sorry, I agree with xylene. I was trying to remember the name. I stay away from toluene since its highly carcinogenic. I am sure outside, with protective gear, etc but why mess with it for a hobby?

 

Actually benzene is the real bad actor. Toluene isn't really that harmful from a cancer perspective. It is stinky and can get you high in a bad way, but used carefully and in moderation, no real problems. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1469723/

 

Thanks everyone. I'll see if I can pick up some of the xylene tomorrow. I'll let you know if it works.

 

cruel!
oh, so cruel.

 

I would try water first and acetone after that and stop there. No rubbing of any kind. To me the coin looks like it lost it's skin to a cleaning long ago and the spots grew from there. I don't think they will come off without doing damage to the coin. A dip might remove part of them but that would probably leave the coin looking worse.

 

I can't tell the nature of the spots from the photo, but I'll bet they're in the metal and not surface gunk, in which case I'd leave it alone and sell it if the spots bothered you too much.