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 Replies: 16 / Views: 1,091 |
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Valued Member
United States
209 Posts |
Just received the 2021 Proof set from the U.S. Mint. The Crossing the Delaware quarter has strange blue streaks on the obverse left of the bust and all around IGWT. Anyone have any information as to what would cause this?   |
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Moderator
United States
112247 Posts |
They look like scuff marks. Are they on the plastic? The lens is not sealed. You can carefully open and investigate.
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Valued Member
United States
209 Posts |
I'll open the case and see....
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Valued Member
United States
209 Posts |
I opened the case and found that the blue streaks were on the coin, not on the case. I used a soft cloth to see if the streaks would wipe clean, and they did! Could be something used at the mint to polish proof coins which left a residue?
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Bedrock of the Community
United States
44659 Posts |
Can we see after pics? You should never use a cloth on a coin especially a proof. John1  ( I'm no pro, it's just my humble opinion )
Searched 6.5 +/- Million Cents Since 1971
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Valued Member
United States
209 Posts |
Will do, John. I'll post pics later this afternoon.
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Moderator
United States
112247 Posts |
Quote:
I opened the case and found that the blue streaks were on the coin, not on the case. I used a soft cloth to see if the streaks would wipe clean, and they did! Glad to find it was not permanent damage, but wiping a proof coin could have made things worse. I would have preferred an acetone soak followed by a fresh acetone rinse. Quote:
Could be something used at the mint to polish proof coins which left a residue? Seems to me it is more likely grease from the minting equipment.
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Valued Member
United States
209 Posts |
Here are photos of the coin after it was taken out of the holder, and lightly cleaned with a soft cloth to remove the blue residue. Should I soak the coin in acetone to more fully clean the coin?   |
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Pillar of the Community
United States
2092 Posts |
Coin looks good to me. I suggest not messing with it any further.
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Valued Member
United States
209 Posts |
Thanks for your response, NumisEd. Since I took it out of the holder and gently wiped off the debris, I didn't know whether it would be best to give it the acetone soak for conservation before returning it to the holder, or just leave it as is.
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Valued Member
United States
209 Posts |
Jbuck, thanks for your input. Regarding your comment about the possibility there was grease on the coin---is there any significance to the fact that the streaks on the coin were blue in color? And if this was grease, could that affect the long term appearance of the coin when I put it back in the holder?
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Pillar of the Community
United States
8068 Posts |
Acetone cannot hurt your coin. If this was some sort of contaminant, it might be a good idea to use the acetone on it. But its your decision.
As to using the cloth, try forced air next time a situation like this comes up. Even something as simple as an eye dropper can work for some things.
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Pillar of the Community
United States
1276 Posts |
Excellent work at removing them. The original images remind me of those notorious milk spots found on late-sixties/early seventies proofs which turned out to be a cleaning residue used by the mint. And those are embedded into the coin.
ANA member - PAN Member - BCCS Member There are no problems only solutions - the late, great John Lennon
Edited by Ballyhoo
08/17/2021 09:10 am
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Moderator
United States
112247 Posts |
I would definitely give it an acetone treatment. Some of the containment could remain. If it was grease, a remaining thin layer may have been what prevented the cloth from scratching the surface. Remember, any acetone soak is followed by a flowing rinse with fresh acetone (not the batch you used for the soak). Do not rinse with water! Do not wipe dry! Fresh acetone should air dry faster than you can whip out a cloth to wipe it!  |
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Valued Member
United States
209 Posts |
Thanks jbuck, Ballyhoo and Earle42 for your input.  If I had not investigated and left the coin in the holder for an extended period of time, who knows? The grease/polish or whatever may have permanently damaged the coin. I am going to give it an acetone bath, and then an acetone rinse followed by an air dry ---just to make sure there is no additional contaminant on the coin. |
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Moderator
United States
112247 Posts |
Sounds good!  You are welcome.  |
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Replies: 16 / Views: 1,091 |
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Posted 08/16/2021 12:40 pm
