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 Replies: 7 / Views: 5,758 |
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Pillar of the Community
United States
2111 Posts |
I purchased a dime taking a chance it might be something special, I was informed it was an acid dipped coin, So I wanted to see which acid would cause this damage. None of these acid baths matched the dime damage I have. These three dimes were in three different acid baths for approx 30 days, Dime one, Muriatic Acid, Muriatic acid did the most damage, It also did more damage to the copper part of the Dime, It weighs in at 1.7 grams. Dime two sat in Sulfuric Acid, This caused the least damage, and weighs in at 2.2 grams, and Dime three sat in Hydrochloric Acid, it changed the appearance of the dime mostly the color, and caused some surface damage. Still none match the dime I have which still has the reeding, and weighs in at 1.1 grams. Now I am not stating my coin is not acid bathed its just I can't duplicate my dime condition with those three acids. On the Muriatic Acid Dime, I can fit my dime between the Obverse and reverse sides, the inner copper has receded far enough that the reeding is completely gone. So I can definitely rule out Muriatic Acid. I don't believe based on my experiment that those other acids caused this damage. Please tell me what you think.  Muriatic Acid  Sulfuric Acid  Hydrochloric Acid         "LOVE THE HUNT!"
Edited by arby96
11/14/2019 4:06 pm
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Moderator
 United States
188130 Posts |
Very interesting!  |
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Pillar of the Community
Canada
5239 Posts |
That is quite interesting, in a Stephen King kind of way.
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Pillar of the Community
Canada
693 Posts |
I think traditionally for the experiment, Coca Cola is used : phosphoric acid...
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Pillar of the Community
 United States
2111 Posts |
I will try coca cola next then, I am determined to duplicate my coin. we will see what happens.
"LOVE THE HUNT!"
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Moderator
Australia
16817 Posts |
Just FYI: "muriatic acid" and "hydrochloric acid" are different names for the exact same chemical - as you will discover if you type "muriatic acid" into Wikipedia. They might be sold under different names at different concentrations.
How acid will react to a coin will also depend on the initial condition of the coin; we haven;t seen the "initial" photographs of the acid-soaked coins. I assume they all looked much the same? It's important in scientific experiments to control the variables, and one variable that's important in chemical reactions is starting conditions. Ideally, you want to take coins with identical levels of preservation - such as taking them all out of mint rolls. Ideally, you'd want to use 1972 coins (or coins of similar date to your "unknown", as the changes in production techniques may also be relevant. You'd also ideally want to include replicates, to make sure one of the coins isn't unusual in some way.
Acid will also behave differently to metals at different strengths. And it is not necessarily a linear progression. Concentrated sulfuric acid will react differently than sulfuric acid that is more dilute, as different chemical reaction occur in concentrated sulfuric acid. To get concentrate sufuric acid to react with metal, you really need to heat it up.
Copper is generally more prone to acid attack than cupronickel alloy, so any strong acid is likely to result in what you have observed: the copper core being eaten away faster than the clad layer, creating a "hollow sandwich" appearance. A weaker acid over a more prolonged period might cause a different reaction. Try phosphoric acid; I believe that does not strongly react with copper, especially oxidized copper.
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
United States
191 Posts |
Thank you, @Sap. Very enlightening information.
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Pillar of the Community
United States
822 Posts |
Interesting topic. In my experience, "dipped" coins were typically silver, to remove tarnish. I've seen it done a few times. I don't know what the fluid was, but the dip usually took only a couple seconds to have the desired effect. Beyond that it started to affect the surface of the coin and became easily identified. I hadn't considered treating a clad coin with acid. From a practical view, what would be the purpose?
Edited by GregAlex
04/26/2020 6:32 pm
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Replies: 7 / Views: 5,758 |
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Posted 11/14/2019 5:27 pm
