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 Replies: 12 / Views: 3,411 |
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Valued Member
Canada
202 Posts |
Hi, I did a search on acetone bath just to avoid repeat threads, got a few hits but was wondering about this aspect..
I saw an ad for an ultrasonic cleaner - the liquid used isn't the question, as I already know that if I were to use it on anything not ridiculously valuable, it would be 100% acetone, lab strength if possible.
But the machine itself, I've had it done with my glasses and jewelry, with great results - all the tiny crevices get done, and without any handling, the ultrasonic sound waves just shake the gunk free apparently.
Has anyone tried this with coins? I'm thinking of that black oil/grime that collects in the denticles or fills in the A's or 6's on the coins.
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Bedrock of the Community
 United States
24939 Posts |
One thing to worry about is the coin sitting on the metal bottom of the sonicator bath, being jiggled 1000X per second.
Inordinately fascinated by bits of metal with strange markings and figures
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Pillar of the Community
United States
2003 Posts |
Perhaps if there is a way to suspend the coin in the solution?
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Pillar of the Community
Canada
1505 Posts |
I wonder if you could use something like the inside of a PCGS/NGC holder or would the acetone eat that as well as any other stuff?
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Pillar of the Community
 Canada
9862 Posts |
I've tried it.
For silver coins it's no more effective than water, nor is it any more effective than a simple acetone dip.
The black grime is tarnish and is not soluble in water or acetone.
"Dipping" is not considered cleaning...
-from PCGS website
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Moderator
United States
56855 Posts |
You can use the search box upper left of page for info on the machine, I do not recommend it. I read a post here a long time ago about using an air brush machine using 100% pure acetone, always wanted to try it but never did. Maybe a member who already has an air brush machine can try it and post before and after pics  John1  |
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Bedrock of the Community
United States
19115 Posts |
Heads-up! Acetone is very, very flammable. Personnaly, I would not use acetone in close proximity to a runnering electrical device.
Edited by ijn1944
02/09/2023 6:59 pm
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Moderator
Australia
16806 Posts |
Two issues here.
One is theoretical. For ultrasonic cleaning to work, you need to have a solution capable of forming microscopic bubbles, which subsequently implode. It is this implosion that generates the cleaning action. For this to occur, you need a liquid with low surface tension. Water has high surface tension, so you need to add surfactant (soap) to reduce the surface tension. If you just put pure water in a sonicator, nothing much happens because the surface tension is too high for the micro-bubbles to form. Acetone has lower surface tension than water (most liquids have a lower surface tension than water), but I don't know if it's low enough for a sonic cleaner to be effective. You might need to add a soap to the acetone to get it to work properly. You also need to take care when working with a large open vat of acetone as its vapours are flammable; the water bath is electricity-powered and may not have been designed to be spark-proof.
The other issue is practical. An unintended side-effect of ultrasonic cleaning is "rubbing". Everything immersed in an ultrasonic cleaner rapidly moves back and forth in response to the sound waves. Any two objects touching each other will vibrate against each other, causing "rub" at the point of contact. So while ultrasonic cleaning is in theory very good at cleaning coins, in practice it is impossible to levitate the coin in the middle of the solution without touching anything. Even tying a piece of string around the coin to suspend it in the bath won't avoid it, because the string and coin will then rub against each other.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Valued Member
 Canada
202 Posts |
and that's why I love this group.. excellent insight and answers! thanks, I was pretty sure I wasn't going to do it, but it's good to have solid scientific reasoning
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Bedrock of the Community
Australia
21786 Posts |
Metal in a microwave is dangerous.
Nevertheless, has anyone tried entirely covering a coin and suspending it in distilled water inside a microwave, to clean it ?
Could the same thing be done by entirely submerging a coin in distilled water, and bringing it to the boil?
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Moderator
Australia
16806 Posts |
Metal in a microwave is dangerous, because it overloads and destroys the microwave. Water is a very efficient absorber of microwave radiation - that is, after all , why microwave ovens work int he first place - but there would be a very fine balance to be found, between putting not enough popwer in the microwave (and therefore not heating near the coin) and too much power (allowing the metal itself to absorb much of the microwave energy.
Boiling water is indeed one of numerous possible cleaning methods used to clean ancient "uncleaned" coins. However, for more modern coins, it would probably be best to avoid any kind of applied heat to a coin, because heat accelerates chemical reactions, and if there's anything stuck on the coin that might react with it, hot water might cause the reaction to happen faster. One advantage of sonication is that it doesn't generate excessive heat.
The other difficulty being, of course, how to get "boiling distilled water". Unless you've got some kind of fancy lab apparatus, anything you put distilled water into that might cause it to boil (like a jug or urn) will likely cause some component of the heating apparatus to dissolve in the boiling water, contaminating it - so it's no longer pure water any more.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
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Moderator
United States
56855 Posts |
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Pillar of the Community
Canada
2781 Posts |
Quote:
Heads-up! Acetone is very, very flammable. Personally, I would not use acetone in close proximity to a running electrical device. THIS. |
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Replies: 12 / Views: 3,411 |
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Posted 02/09/2023 5:05 pm
