Identify that damage! #5

Did you miss me? Yes you did.

I'm back with another round of Identify that Damage!

Today's contestants are this trio of Lincolns that are showing off a little too much to be chaste. Looks like the copper was somehow stripped off in places. One of them was obviously the victim of a vitrioleur, but what about the other two?

 

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3rd Cent.. Copper plating was stripped due to environmental exposure. Zinc Rot

 

^winner!

 

Here is a nice Zinc rot .. Found metal detecting

 

that's disgusting! but really neat

 

So that's what our coinage will look like (or worse) in a few decades when dug up? Zinc rot. I never heard of it, but I've seen that common white corrosion on zinc world coins. I guess older copper coins will fare better in the ground than the cheaper zinc coinage we're churning out today

 

Thats crazy!

 

"I will conquer the world with my zinc-eating bacteria."

 

It's funny that the mint picked zinc and copper. Zink plating on ferrous metals is used for it's resistance to corrosion in the presence of moisture, but when used with copper in the presence of moisture, electrolysis occurs. Copper roofs and flashings are put on with copper nails because steel nails are plated with zink.

 

Yeah, I've always said I wondered why they used a sacrificial anode for coinage....

 

I always thought that particular green was indicative of PVC damage, so I thank you for the lesson.

Does anyone have a PVC damaged green coin picture; the kind of damage that they talk about in the beginning collector books? I'm not sure what it looks like.

I guess that it is from the chloride in the plastic reacting with silver; but does it also react with copper? And even more recently I've heard about chlorine reacting with iron in US B.E.P. ink on bills.

 

Sometimes the Mint doesn't seem to make good decisions. See: manganese on "gold" dollars...

 

On the bottom, on top of "Dollar"

 

Ouch. Did that come off completely?

 

I haven't messed with it so I wouldn't harm the coin. It's a 1903 in otherwise MS-64ish condition

 

The copper film on zinc will turn green with verdigris sometimes before the zinc rots.

 

The coin is being harmed by you not doing anything about it. Your lack of action will guarantee the coin will eventually be ungradable. Please research what acetone can do for it.

 

Thanks for the advice. I hear horror stories of folks messing up while dipping/conserving and I don't want to that to be me. It's got some neat toning on the front that I was worried about ruining. But, no tone is better than no grade right?

 

Would this work?:
acetone on cotton q-tip.
rub on green part.
dry off remaining acetone with dry q-tip.

 

Soak it in a glass dish or jar of acetone. It won't touch the toning