Cleaning Copper Coins with Ketchup???

[Garrett424]

I posted this question in the metal detecting category a little while ago but I'm thinking I may get even more info in the coin department (no offense to any MD'r's).

So, here goes.........


"
I was telling a coworker how I cleaned an 1886 Indian Head penny with lemon juice and gave it an olive oil soak and how well it worked (both methods I was completely unaware of before joining this forum so thanks to all for the great info).

He then showed me two very dirty 1990's era pennies. Then he proceeded to clean one of them using nothing but ordinary ketchup and a soft cloth. In a very short time and with a bit of elbow grease the penny looked almost new. The side by side comparison was remarkable and impressive.

I understand that the acid from the tomatoes acts as a solvent but my question is, is this a safe method of cleaning old copper coins and will it damage the coin in any way or affect the value??

If anyone knows I would appreciate any input. If it is safe it's definitely an impressive way of making copper look like new. I would certainly use it on non coin/collectible copper items. The only downside I noticed was the ketchup smell left behind but I'm sure with a bit of water or even lemon juice that can easily be taken care of."

Thanks in advance.

 

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[enamel7]

Yes it is a damaged coin. It is actually removing a layer of the copper, like what tarnex does to silver, thus damage. Any time you use a chemical reaction on the metal itself it is damage.
HH
enamel7

 

[Garrett424]

Thanks. I'll save this method for uses besides old coins.

 

[cudamark]

If it's a common date in the lower grades, it probably wouldn't affect it's value much. It might even improve the value slightly if it's done right. First determine it's year/mintmark and grade. Based on that info, figure the collector value for an unimpaired coin vs. your coin. If your coin is worth under $10, I wouldn't worry too much about potential damage by cleaning it, especially if the coin is real nasty looking in it's present condition. Another good method for cleaning crusty copper/brass coins is to place the coin in the dimple of an inverted aluminum can. Add some vinegar and let it sit for a couple of hours. Remove the coin and rub it with some baking soda and rinse thoroughly with water. You may have to repeat if the coin is real bad. Keep in mind that this will make the coin bright and shiny so it will look like it been cleaned so it's not recommended for a coin with much collector value. Try it first on a copper memorial cent so you can see what it looks like before you try it on an older, more valuable coin.

 

[Garrett424]

Thanks to all for the great info.

 

[enamel7]

Acetone works well on organics on a coin. Baking soda would still scratch it.

 

[collision]

Great Info here! Thanks for sharing