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 Replies: 13 / Views: 943 |
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Valued Member
Australia
136 Posts |
I know coin cleaning is thoroughly discouraged, but these sterling silver coins are very common in high grades and the surface contamination is awful on them. I would like to identify the contamination on them as I haven't see it before. The coins came from an estate auction. They appear to have a grey crust that's baked onto the silver, and look worse in real life than in the photos. The two coins are Australia 1927 commemorative florins. In trying to clean the coins I have tried: - Al/baking soda - no effect on grey surface - Soaking in distilled water / detergent - no effect - Ultrasonic cleaner / detergent - very small amount removed - Vinegar - no effect - Acetone - no effect Any ideas on what the grey could be? My ultrasonic cleaner is a low power budget model. Are more expensive models more powerful? Coin 1:   Coin 2:    |
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Bedrock of the Community
 United States
25004 Posts |
Ouch, ClusterCoin - those coins are hurting! It looks like they were stored in a warm damp place and oxidized, with perhaps some other chemicals in the mix. Your methods won't touch them. You could try a dedicated silver coin dip such as EZest - NOT silver jewelry cleaner. Do a Forum search on how to best use it, as I never have.
Inordinately fascinated by bits of metal with strange markings and figures
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Bedrock of the Community
United Kingdom
17903 Posts |
I very seldom clean coins, but yesterday I got a 1977 Austrian commemorative 100-schillling for below melt at a coin shop - it was in similar condition to your florins. I used Goddard's Silver Dip and the result was spectacular, although I don't know if the coin will tone again afterwards. I wouldn't attempt this on anything valuable but this was basically just a bullion coin and was really ugly and it was hard to make out the details. I rinsed it in water and will give it an acetone dip to get rid of anything left over from the silver dip.
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Valued Member
 Australia
136 Posts |
Thank you for the replies.
Any ideas on what the active ingredients are in EZest and Goddard's? EZest doesn't appear to be available in Australia but Goddard's is.
I have never used it, but Tarn-Off is widely available in Australia and it contains thiourea and sulfamic acid.
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Bedrock of the Community
United States
94367 Posts |
Good luck, keep us informed!
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Moderator
United States
187702 Posts |
Quote:
Any ideas on what the active ingredients are in EZest E-Z-EST is thiourea and sulfuric acid. |
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Valued Member
Australia
136 Posts |
Thank you jbuck. I will give Tarn-Off a go and report the results soon.
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Moderator
United States
187702 Posts |
Quote:
Thank you jbuck. My pleasure.  Quote:
I will give Tarn-Off a go and report the results soon. Good luck!   |
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Moderator
United States
95018 Posts |
Well, just tuning in on this topic - hope it goes well for you.
But all metal is porous and can take a stain that is permanent once it sets. You may be stuck with some of that look no matter what you do (short of taking it to a buffing wheel - which I do NOT recommend)
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Valued Member
Australia
136 Posts |
Well, I dipped the crustiest coin into Tarn-Off (thiourea/sulfamic acid solution) and it did absolutely nothing to the grey crust.
Soaked it over night. No effect.
Whatever this contamination is, it's adhered to the coin and will not be coming off. I'll leave these coins as is. They'll be interesting curiosities to present to other coin collectors.
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Moderator
United States
95018 Posts |
usually once a coin is stained - it is a permanent feature..  |
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Moderator
United States
187702 Posts |
Quote:
Well, I dipped the crustiest coin into Tarn-Off (thiourea/sulfamic acid solution) and it did absolutely nothing to the grey crust.  Quote:
Soaked it over night. No effect.  Quote:
Whatever this contamination is, it's adhered to the coin and will not be coming off.  Quote:
I'll leave these coins as is. They'll be interesting curiosities to present to other coin collectors. Good call. |
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Pillar of the Community
United States
676 Posts |
Carry them around as pocket pieces for a month or two and they should develop a nice circulation cameo as well as getting rid of most of the staining. Downside is they would be at a lower grade and may not have luster left, but if done right they should still straight grade. |
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Pillar of the Community
Australia
9376 Posts |
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Replies: 13 / Views: 943 |
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Posted 07/09/2024 03:06 am
