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Using Acetone On Copper Coins - The Scientific Result Is Out

 
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Pillar of the Community

Australia
3458 Posts
 Posted 04/02/2007  10:24 am Show Profile   Bookmark this topic Add gxseries to your friends list Get a Link to this Message
Posted originally in coinpeople, this site shows what happens when you use acetone on copper coins.

I personally never recommand acetone on copper coins and this perhaps is one of the more scientific studies of how acetone acts on copper.

http://www.sunysb.edu/vescalab/rese...search7.html

Perhaps that is the best proof why some people get their copped coins ugly toned whereas some don't
My partial coin collection http://www.omnicoin.com/collection/gxseries

My numismatics articles and collection: http://www.gxseries.com/numis/numis_index.htm Regularly updated at least once a month.
Pillar of the Community
Belgium
2078 Posts
 Posted 04/02/2007  1:42 pm  Show Profile   Bookmark this reply Add ageka to your friends list Get a Link to this Reply
This makes a lot of sense

Acetone was/is the prime ingredient in nailpolish remover also as far as I know acetone was the only product to remove unremovable ink
( waterresistant ink )

If I had to move to the next in line for metals I would move to MEK
Methyl Ethyl Ketone

Pillar of the Community
United States
5841 Posts
 Posted 04/02/2007  2:32 pm  Show Profile   Bookmark this reply Add Jaobler to your friends list Get a Link to this Reply
From my organic chemistry days, I remember that Methyl Ethyl Ketone (MEK) is very similar to acetone in structure (CH3COCH3 vs. CH3COCH2CH3]. If acetone can react with water to yield acetic acid and methane (CH4), I would expect MEK to be capable of a similar reaction which could yield acetic acid and ethane (CH3CH3). Based on this article it sounds like isopropyl alcohol would be the safer choice for drying copper coins. Methyl alcohol would almost certainly also be safe and since it has a lower boiling point would evaporate more quickly than isopropyl alcohol.
Of course, if you never clean your copper coins, you won't have to worry about these issues!
Pillar of the Community
Belgium
2078 Posts
 Posted 04/02/2007  4:33 pm  Show Profile   Bookmark this reply Add ageka to your friends list Get a Link to this Reply
Whether a reaction goes or not depends on the reaction energy going left or right in the equation
If MEK cannot be activated by UV light with copper then the reaction does not go
Isopropanol cannot be got pure , too much water in it ; water that leaves spots on gold proofs
So for the purist is left pure ethanol distillated and then extracted to 99.9 purity
Costly though
Pillar of the Community
United States
1173 Posts
 Posted 04/02/2007  5:16 pm  Show Profile   Bookmark this reply Add hunter20ga to your friends list Get a Link to this Reply
It appears that light is needed to drive the reaction, and even then it is slow. One might be able to use acetone under low-light/no light conditions and get by just fine. Of course, this will take some experimentation...maybe NSF will pony up a few million to fund this vital research!
Valued Member
United States
376 Posts
 Posted 04/02/2007  7:39 pm  Show Profile   Bookmark this reply Add madspec to your friends list Get a Link to this Reply




(MEK) (CH3COCH3 vs. CH3COCH2CH3](CH4), (CH3CH3).


Excuse me but could you please use English!!!


I do not know how to speak this language.

Madspec
Pillar of the Community
United Kingdom
1150 Posts
 Posted 04/03/2007  10:43 am  Show Profile   Bookmark this reply Add pattiewhack to your friends list Get a Link to this Reply
(quote)Acetone was/is the prime ingredient in nailpolish remover also as far as I know acetone was the only product to remove unremovable ink
( waterresistant ink )(/quote)

Still hasn't worked for me?!?!
Pillar of the Community
Belgium
2078 Posts
 Posted 04/03/2007  10:50 am  Show Profile   Bookmark this reply Add ageka to your friends list Get a Link to this Reply
Pattiewhack

What do you mean ; has not worked on nailpolish ? has not worked on ink ? or has not worked on coins ?

The acetone has to be pure and at least at roomtemperature and anything that cannot be removed by water and soap should be removed by acetone as a solvent .
Acetone will probably not remove coffeestains ( water soluble ) nor wine stains ( water solluble )
Pillar of the Community
United States
5841 Posts
 Posted 04/04/2007  3:10 pm  Show Profile   Bookmark this reply Add Jaobler to your friends list Get a Link to this Reply
"Excuse me but could you please use English!!!"

Sorry Madspec, I posted the chemical formulas for acetone and Methyl ethyl ketone (= MEK) to show they are similar compounds. I'll try to explain my point (in English!):

The acetone molecule has a central carbon atom (C) bonded to an oxygen atom (O) with what is called a double bond. That same carbon atom is also bonded to two methyl groups, each consisting of a carbon atom plus 3 hydrogen atoms (H). According to the article linked by gxseries, the acetone molecule can split apart if exposed to water (H2O) and light. One fragment of the molecule forms acetic acid (the acid found in vinegar). The acetic acid may gradually corrode any copper that stays in contact with the acetone mixture.

Methyl ethyl ketone (MEK) also has a central carbon atom double-bonded to oxygen. The carbon atom is bonded to a methyl group on one side, just like acetone. On the other side it is bonded to an ethyl group (consisting of 2 carbon atoms and 5 hydrogen atoms). My theory is that since acetone and MEK have similar structures and chemical bonds, MEK might behave like acetone and produce acetic acid if exposed to water and light.

In any case, the key is exposure time. If the acetone is clean and you just use it to briefly rinse your copper coins, the risk of causing corrosion is probably zero. If you are trying to remove stubborn stains and want to soak your coins, I'd follow Hunter's advice and keep the container in the dark. The container needs to be tightly sealed so the acetone doesn't evaporate.

By the way, my 2006/07 Fisher Scientific Catalog lists 99.9% pure isopropyl alcohol, at a cost of $78.40 for 4 liters. Isopropyl alcohol is not as effective as acetone for removing organic stains, but this material would leave no water residue when it evaporates and would be totally safe for coins. It's expensive, but you can clean a lot of coins with 4 liters!

PS: these solvents are all poisonous and highly flammable. If you use them, be careful!
Pillar of the Community
United States
2600 Posts
 Posted 04/04/2007  4:25 pm  Show Profile   Bookmark this reply Add Jim1953 to your friends list Get a Link to this Reply
Extremely interesting. Would anyone be interested in extending the thought process on the effects to nickel, silver or gold. I have used acetone successfully on copper but my soak times are very short. Mainly just removing the real hairy organics. Afterwards they are soaked in distilled water and air dried.
Thx Jim
Pillar of the Community
Belgium
2078 Posts
 Posted 04/04/2007  4:50 pm  Show Profile   Bookmark this reply Add ageka to your friends list Get a Link to this Reply
jaobler
I only used isopropanol because I paint on silk using batik
which is heated beewax drawing lines with a tjanting and then putting fluid colors inside the lines
Afterwards you iron the silk betweek paper to take most of the beewax away and then you put it in isopropanol because it is the cheapest alcohol like solvent and you need to wash the scarf or tie in the stuff and afterwards you fix it with NaoH and then wash it in water

When talking coins ; if you do not sniff or inhalate why not use methanol after all artificial sugar like aspartame is carried in methanol during production
In a fix I will just use vodka for degreasing my taperecorder or videorecorder or cleaning my electronic switches after all vodka is cheap 40% ethanol

After years of testing I stick to acetone for degreasing and trichloroethylene for drycleaning my silk scarfs and ties and paintings

Jim
900/1000 gold can only be damaged by strong acids or caustics if it has copper
0.9999 gold can only be damaged by aqua regea a mixture of two acids
( beware of phosporic acid )
Pillar of the Community
United States
2600 Posts
 Posted 04/07/2007  10:26 am  Show Profile   Bookmark this reply Add Jim1953 to your friends list Get a Link to this Reply
Thx, ageka.
Jim
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