I like Cleaned Coins and you should to thread

What you say is true, but don't freak out on them. Punchy as a painter may be true, just like Mad as a Hatter, but that comes after repeated long-term exposure. Should be careful with flames though, since they are very flamable.

 

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Substitutes for acetone

I am not much of a coin cleaner, but I know a little about chemistry.

Is there a particular reason why other chemicals are rarely mentioned as cleaning agents besides acetone? I have recently noticed that denatured alcohol is generally a superior (and a bit safer) than some of the more "energetic" cleaners out there. And MEK, methyl ethyl ketone, is a close relative of acetone.

The other issue is the use of water-based surfactants. Not necessarily the ones found in detergents, but there are a lot of surfactants that can chemically dissolve some of the tougher, dirtier contaminants on a coin. So here are a few ideas I have as alternatives to pure acetone...

• Avoid acids, bases, oxidizers, and salts. Do not use trisodium phosphate or similar chemicals, bleach, peroxides, vinegar, abrasives, soda, powders, gritty liquids, soap, pastes, or household cleaners.
• This leaves you with hydrocarbons, water, alcohols, ketones, and the like... industrial and commercial raw chemicals that are not reactive with the metals of a coin.
• Try things readily available and pure chemicals. Do not, for example, choose a household oil formulation or a motor oil. Both of these have numerous additives.
• Denatured alcohol is ethanol that has a little methanol in it to make it poisonous. It is a powerful polar solvent. You can get this and most of these things at a local hardware store like Ace or True Value.
• Isopropyl alcohol is that stuff you put on your minor cuts and scrapes. It dries fast and it is a polar solvent. It is cheap and available up to 90% next to the Band-Aids at the pharmacy.
• MEK or methyl ethyl ketone is just like acetone. It is an alternative with very similar properties.
• Toluene is a non-polar solvent. It would be able to remove chemicals that acetone and ethanol cannot. Dries quick. It is technically an aromatic.
• Xylene is very much like toluene but dries slower. They can substitute for one another.
• Mineral oil is a non-polar solvent. It will essentially never dry, however, so to remove the residue after cleaning, you must clean it with something like a detergent or toluene, xylene, etc. You could use mineral oil to submerge a pretty coin indefinitely, and it will never oxidize or tarnish because there won't be any air inside. This might work for a safe deposit box or a hidden cache.
• Water is a good solvent, too. Use only distilled water for cleaning. It dries slowly and it can react with dirt and corrosion to produce more corrosion. Use sparingly.
• When added to water, some detergents will have a high pH like a base and are unsuitable. But some detergents may be mild, and especially when enhanced by a surfactant. It is my guess that a so-called Coin Dip fits into this classification. One of the advantages of this type of cleaning is the use of bubbles, which uses air to do some of the attack. Alternating solvents with entrained air results in cleaner surfaces.
• Speaking of air, I don't hear too many people discussing canned or compressed air. There are gaseous solvents available for industrial cleaning, and although expensive, this type of cleaning should be considered. This is like the industrial equivalent of canned air.
• High or low temperatures are good ways to enhance cleaning of a coin. All coins are temperature stable over a much wider range than most contaminants (except of course corrosion). Heating a coin can be attempted to help the solvent process. Just remember that acetone and other chemicals are flammable. It should go without saying that it is possible to overheat a coin and damage it. But if you read up to this point, you should know this. You can't, for example, pop a dirty coin into your oven and have it come out clean. Copper and silver will both tarnish and oxidize easier at high temperature, so you may need to use a heat process where oxygen is not able to attack the coin by using nitrogen atmosphere or do it submerged in a solvent. The idea about low temperature is to freeze the dirt and let the coin remain.
• Ultrasonic. WHY HAS NO ONE mentioned this? Isn't this the method that jewelers use to clean precious metals? Is this a BIG SECRET?:yes: Ideally, sounds will break down dirt and cause it to fall off.

Note: I am using the word "detergent" in the chemical sense. I don't mean to imply that Tide with Bleach is a great coin cleaner.

 

Can we use Benzene?

 

It is not a big secret, it is just a bad technique. If you can devise a way to suspend the coin in the solution while using the ultrasound, it might work, but the coin will either rest in a plastic carrier or a metal container, and either one can put scratches or marks on a coin ( particularly a copper or silver one) as the coin will vibrate also.

Also the reason jewelers can use it , is that it is Ok for them to polish any marks out, whereas polishing is not for coins.

 

Off subject but what happened to mrbrooklyn?

 

I like finding cleaned coins in the bottom of the washing machine. I call 'em recycled allowance: nickels and quarters are all shiny, and the pennies usually have a nice hue.

 

Nice post, thank you!

 

When I was in college, we used to practically bathe in benzene, it has since proven to be a rather bad carcinogen and I don't see it in use at all nowadays. Avoid it. Toluene or Xylene - gotta do a study with them on copper.

 

If someone knows, please let us know.

 

• 
  
  Many types of cleaning will tend to "strip" coins, affecting the natural finish or luster. The surface of the coin can be delicate and cleaning with an ultrasonic can make a surface appear granular. In most things, give it a try, but try it on coins you can afford to lose. Let us know the results.

 

So, if you use acetone, do it in the dark.

 

I have read that article cited and my complaint is that no indication of the amount of water vapor, the intensity of the ambient light, the treatment of the foil before testing, why they allowed the acetone solution to remain until evaporated, thus concentrating any acetic acid, and also why was it not done in sealed containers to eliminate any other chemicals that might be in the air of the lab and concentrated by the drying.

I do not disagree that photolysis of acetone might occur, and that acetic acid formed, but I certainly have never recommended the conditions they used with their experiments. Actually my opinion is that it was a poorly done experiment, IMO.

I beg to differ.

Jim

 

Carbon Tetra Chloride. Works great when a penny is in your pocket.

 

Carbon Tet

Carbon tetrachloride is a dangerous chemical, causing liver damage as well as being a proven carcinogen. If you use it, use it in a well ventilated space and be careful of skin contact. Otherewise, a wonderful non-polar cleaning agent.

 

Was the primary component

 

Yes

 

Oh stop. I used it in the laundry mat all the time. And I might add that the coins always came out of the pockets very clean

 

From Wikipedia: Exposure to high concentrations of carbon tetrachloride (including vapor) can affect the central nervous system, degenerate the liver[SUP][10][/SUP] and kidneys[SUP][12][/SUP] and may result (after prolonged exposure) in coma and even death.[SUP][13][/SUP] Chronic exposure to carbon tetrachloride can cause liver[SUP][14][/SUP][SUP][15][/SUP] and kidney damage and could result in cancer.[SUP][16][/SUP] More information can be found in Material safety data sheets.[SUP][17][/SUP]
In 2008, a study of common cleaning products found the presence of carbon tetrachloride in "very high concentrations" (up to 101 mg m[SUP]−3[/SUP]) as a result of manufacturers' mixing of surfactants or soap with sodium hypochlorite (bleach).[SUP][18][/SUP]
Like many other volatile substances, carbon tetrachloride is prone to misuse by inhalation, due to its possible depressant and/or dissociative effect upon the central nervous system. Use of carbon tetrachloride in this manner presents serious health risks, and may result in toxic effects described above.
Carbon tetrachloride is also both ozone-depleting[SUP][19][/SUP] and a greenhouse gas.[SUP][20][/SUP] However, since 1992[SUP][21][/SUP] its atmospheric concentrations have been in decline for the reasons described above (see also the atmospheric time-series figure). CCl[SUB]4[/SUB] has an atmospheric lifetime of 85 years.[SUP][22][/SUP]

 

Anyone got a suggestion for this coin? I treated it with verdicare after soaking it in distilled water and acetone. The 1853 braided hair turned out good, it only had a blob of verdigris at 9 and 10 o'clock.
Before treatment:

After: