How to safely remove ink from gold coin?

Hi,

I'm new to this forum.

I bought a $5 liberty gold coin that has what appeared to be ink on the coin. Is there any safe way to remove it? I have put the coin in pure acetone for around 20 min but nothing changed. Also, do you think the black lines in the coin is from ink?

 

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Acetone is usually good to remove marks like this, however sometimes it isn't. The next thing to try is xylene or toluene.

 

The good news is that it's pretty hard to "hurt" the gold, chemically. Stay away from stuff containing chlorine.

 

If I already soaked the coin in Acetone for 20 min and it did nothing, will it make a difference if I soak it for longer time? Say 2 hours? Or should I use different chemical such as xylene as suggested?

 

Acetone can't hurt the coin. Let it soak over night. Try xylene next.

 

I don't think it is ink.

I think it is streaks from an improper alloy mixing. That is part of the coin, and was made that way. No amount of chemical treatment is going to fix that.

 

physics-fan3.14, posted: "I don't think it is ink. I think it is streaks from an improper alloy mixing. That is part of the coin, and was made that way. No amount of chemical treatment is going to fix that."

This is mostly correct. They are impurities that were rolled into the strip and remained in the planchet. Usually they can be removed completely with acid but the coin will have craters remaining where the debris fill now.

IMO, the value of the coin is "killed" for most collectors; however, an error collector or grading instructor may wish to add it to their collection. If you are in the "right" tax bracket for write-offs, donate it to the ANA for a good price.

 

I've seen high graded valuable gold with marks like these. Just leave it.

 

I would agree with this. My first thought is if it was ink acetone would have removed it. Since it did not, I then thought of it as looking like slag that was mixed into the alloy. Slag is the impurities that rise to the surface during the refining process. Not all of it gets separated and some can remain behind. Because gold has a higher specific gravity than the other impurities the slag appears on the surface of the coin. It's found in silver coins as well.

 

You can use chlorinated solvents, just nothing that isn't covalently bonded, like salts. Methylene chloride, Chloroform and Carbon tetrachloride are fine.

 

Are the black lines on the reverse also?

 

So is this a mint error?

No black lines on the back

 

Based on some of your replies, is this coin likely get graded as an error coin by PCGS, NGC or ANACS?

 

I would caution against using these types of solvents unless you have chemical laboratory experience. Some of this stuff can be really nasty if it gets on you or goes down the drain

 

I wouldn't consider this an error worth designating. In extreme cases, however, they will annotate it on the slab. Unfortunately, this type of streaking lowers the value, not enhances it. See here for an example: https://coins.ha.com/itm/errors/192...9-8994.s?ic4=ListView-ShortDescription-071515

I would, however, caution against trying too hard to remove the streaks. You could get a details grade for "streak removed," like these: https://coins.ha.com/itm/liberty-ea...6-4897.s?ic4=ListView-ShortDescription-071515
https://coins.ha.com/itm/liberty-do...4-5549.s?ic4=ListView-ShortDescription-071515

 

I'd leave it alone, on coins like this where the strips get chemically removed 'no idea what's used but I'm assuming dip of some sort' there is usually a very noticeable color difference in the area where the strip used to be.

 

Yes, I should have mentioned it. And make sure it is of a high grade so that it doesn't leave any residue on the coin/medal.

 

It's not slag - the metals have been purified several times. It is copper. It turns to copper oxide, which is black.

 

mmmmmmmmmmmmmm chloroform, one of the best smelling chemicals...

 

Before disagreeing with much of this, I'll just write that I have some experience with coins such as this.

physics-fan3.14, posted: "I wouldn't consider this an error worth designating. In extreme cases, however, they will annotate it on the slab. Unfortunately, this type of streaking lowers the value, not enhances it. I would, however, caution against trying too hard to remove the streaks. You could get a details grade for "streak removed."

This type of problem does lower a coin's value significantly. However, it is a minting error as it happened at the mint due to an imperfect planchet. In many cases, it appears as just a discoloration of copper metal (improper mix) on the surface. If coin dip is applied, the streak turns back to "pink" copper color. In other cases, the black is some form of debris that has become lodged into the coin. It was either in the planchet or fell on to it before the coin was struck.

As I posted, acid will remove debris or turn the copper pink. The ONLY time you will get a spot removal is when some idiot tries to scratch the debris off. If it is dipped and the streak turns pink you may get a "cleaned" designation. Over time, any copper will become dark again.

Blissskr, posted: "I'd leave it alone, on coins like this where the strips get chemically removed 'no idea what's used but I'm assuming dip of some sort' there is usually a very noticeable color difference in the area where the strip used to be."

Not entirely true. If it is debris, the surface will look like a planchet flaw or a place where a strike-thru fell out. If copper streak, the color will change as this poster wrote.

TheFinn, posted: "It's not slag - the metals have been purified several times. It is copper. It turns to copper oxide, which is black."

While this is true, without seeing the coin, most of the time it is a copper impurity yet many times it is a substance that does not belong on the coin that can be removed chemically.