cleaning pennies

I have several pennies that have gunk on them that I'd like to clean off to preserve the coin as best as I can. Is there any way to do this without devaluing the already devalued coin just to try to preserve it? Is there any way to get malachite off a penny or do you just leave it?

 

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Pics would help a lot.

 

Smear 'em with Vaseline and set them aside a week. May not do any good, but won't hurt the coins either. If the gunk's organic, it may all come off without a trace; don't use Vaseline on silver coins.

 

By malachite, I assume you mean a green color. Usually refered to as verdigris. If the cents are valuable or you want to add some value, treat them with VerdiCare. If you just want to get the stuff off, try water soaking with possibly some baking soda added, rinse them and change water often.

 

Baking soda will brighten the fields, but leave the details dark; I don't recommend it. It's a powerful chemical.

 

Baking soda is a powerful chemical???!!!

 

I don't wanna make it look shiny or anything. There's just some that have gunk that looks like jelly on them or the ones that have the blue-green junk on them. Was hoping maybe I could make them cleaner without making the coin worse.

 

Yes, baking soda is a powerful chemical. Any compound that contains sodium, one of the most reactive of all metals, has the potential to harm coin surfaces. Here are some of the industrial uses:

• 5 Applications
  • 5.1 Fire extinguisher
  • 5.2 Cooking
  • 5.3 Neutralization of acids and bases
  • 5.4 Medical uses
  • 5.5 Personal hygiene
  • 5.6 In sports
  • 5.7 As a cleaning agent
  • 5.8 As a biopesticide
  • 5.9 Cattle feed supplement

 

So we should be careful not to ingest sodium chloride? To say nothing of the dangers of dihydrogen monoxide (DHMO) which can kill if it is inhaled? : - )

 

Actually, AFAIK, baking soda is relatively mild and using it in a bath to neutralize acids would not harm coins. Now start scrubbing them with baking soda and that is a different matter.

 

Why do you think scrubbing them is harmful? It's because baking soda is abrasive. Neutralize acids? What do you get when you neutralize acids? Various mineral salts + water. I don't think baking soda is a very good additive.

 

Scrubbing coins with or without any added agent is not really a process that I would recommend because of the possibility of adding scratch marks. If a paste of baking soda and water is used, it will be abrasive (used for cleaning teeth). Sodium bicarbonate is a compound that can neutralize either acids or bases and can solubilize many contaminants without doing any harm to the coins as long as it is rinsed off.

 

Sounds like some organic contaminant. If you have any alcohol around, you could try that, but you would probably have better luck with acetone.

 

Acetone won't damage pennies?

 

There is some contention (Doug...are you there) that acetone will discolor copper. If these are kind of trashy already, probably no problem. Otherwise could use toluene of xylene.

 

Boom!

I'll stick with vaseline for about 48 hours. But acetone does a great job on silver coins, especially cloudy (not dusty ) Proofs.

 

I use acetone all the time, pure acetone. You can get it at CVS or other places. Use a q-tip and then dip it in acetone and lightly rub the stuff off. Don't use this technique on proof coins or probably even mint state coins (unless very, very lightly). If the coins are quite circulated and have stubborn grime, you might have to rub harder than usual. Test this technique on a few coins to get a feel for it. I've used baking soda on nickels before and it works better for those, not so much for cents or anything else.

 

Acetone is fine, use it OUTDOORS. I put an 1/8th of an inch in a small glass bottle and don't rub the coin at all, no Q-tip, just let it soak 15 minutes. I prefer coating with Vaseline for 2-3 days, that removes light greenish corrosion too.

Especially useful for coppers that have been in a Whitman folder for years and years, it really freshens the coin without a hint of shiny-ness. Vaseline is an organic solvent.

 

I'm too impatient which is probably why I use acetone and lightly swab with q-tips. I do sometimes just dip the coins in it, but I've never done so for more than a minute. I'll try 15 mins sometime. I think Vaseline is interesting. So, do you always have to leave it on for 2-3 days? Is there any other way to use it? And when you take it off, how do you do so without rubbing the coin? Thanks, just curious

 

Yes, the petroleum compounds are very mild and work slowly. I don't worry about rubbing the coins, which are circulated. A harsh rag might leave some tiny lines on a Proof, but all this hand-wringing about a soft cotton rag damaging a circulated coin, in my opinion, that's baloney. There are chemical ways to speed up the process, but it's dangerous, and I'm not going to discuss the method.

By the way, coin supply stores sell cotton gloves for people to wear to handle coins, to protect them from fingerprints, sweat, and salt. That's good enough for me.

edit/// My favorite rag? An old 100% cotton bedsheet, cut into 24-inch squares. NO Permanent Press. Go to an estate sale and buy the most worn-out sheet you can find, probably about a buck. Wash in hot water frequently; every time it gets softer and more absorbent. The Vaseline you started with was yellowish-white; what comes off the coin is usually yellowish-green, meaning it dissolved a thin layer of almost-invisible corrosion and other contaminants, and the coin looks 100% better, but not shiny or polished. Do not put Vaseline on silver or gold.