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 Replies: 8 / Views: 1,161 |
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Pillar of the Community
 Australia
2503 Posts |
So I have 3 spare N.Z silver half crowns - 1933's and the worst of them was totally tarnished as seen below. I decided to give it an ultrasonic bath in tap water!! - with a half teaspoon of Palmolive dish liquid!!!(radical I know, but luckily I didn't care too much) The results to me were unexpected. The bath duration was 3 x 5 minute sessions.   The Ox moves slowly, but the Earth is patient.
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Moderator
United States
34397 Posts |
@ttk, what do you think that green stuff was on the king's cheek and collar?
Added: ok never mind. I see you mentioning PVC in the thread title now.
"If you climb a good tree, you get a push."
-----Ghanaian proverb
"The danger we all now face is distinguishing between what is authentic and what is performed."
-----King Adz
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Pillar of the Community
Australia
1364 Posts |
Quote:
I decided to give it an ultrasonic bath in tap water!! - with a half teaspoon of Palmolive dish liquid!! What brand of ultrasonic cleaner did you use? |
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Moderator
Australia
16809 Posts |
An ultrasonic bath with detergent will certainly remove PVC goo. It shouldn't remove tarnish, so I suspect whatever the "tarnish" was, it wasn't regular tarnish.
Sonication is, in theory, an excellent cleaning method for coins. The problem occurs where theory meets practice.
1. Sonciation needs detergent to be effective. Is the detergent going to be long-term harmful to the coin? If it contains sulfur - and many detergents do - then the thin layer of detergent molecules sticking to the surface of the coin could well cause accelerated tarnishing in the years to come.
2. The main drawback to sonication is physical: how do you suspend the coin in the bath, without it touching anything? Because anything that touches the coin is going to vibrate back and forth, really fast, at that point of contact. Another English word for "moving two surfaces rapidly against each other" is "rubbing", And as we all know, "rubbing" is bad for coins. It doesn't matter what that second surface is - the metal sides of the bath, a plastic basket, your fingers, or even a piece of string tied around the coin. Since there is no way of magically levitating a coin inside the bath without it touching anything, then "rub" of some kind is inevitable. For a circulated coin like this one, it's not going to make terribly much difference, but for an uncirculated coin, a sonic bath is likely to push the coin down into AU territory.
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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Pillar of the Community
 Australia
2503 Posts |
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What brand of ultrasonic cleaner did you use? It's an Easy Home Cleaning brand, made for Aldi in Australia anyway, don't know about overseas. The model number is 810652. Cost $20 on sale. I originally bought it to clean jewellery that I find occasionally detecting. The Ox moves slowly, but the Earth is patient.
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Pillar of the Community
Australia
2503 Posts |
And as Sap has said, it's not something you would use on a coin of any significant value. I just sat it in the plastic basket hooked into one of the slots.
It was an experiment and I wouldn't advocate it's use in the pursuit of 'clean coins'. Circulated coins get dirty from doing their job.....being money. It's meant to change hands.... that's the whole reason for it.
If a work of art is desired, I'd suggest to buy it new or really well kept.
The Ox moves slowly, but the Earth is patient.
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Moderator
United States
56855 Posts |
Next time try distilled water and original Dawn liquid dish soap (the blue one). John1  |
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Pillar of the Community
Australia
2503 Posts |
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Next time try distilled water and original Dawn liquid dish soap (the blue one). Thanks John1 I'll keep that in mind. The Ox moves slowly, but the Earth is patient.
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Bedrock of the Community
United States
19126 Posts |
Interesting procedure and discussion.
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Replies: 8 / Views: 1,161 |
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Posted 09/12/2022 7:08 pm
