Cleaning coins.

[Moonlight Sonata]

I'm curious about cleaning coins and the pros and cons. I've read a few opinions, all of which are to NOT clean the coins! And of course I understand that if a coin is cleaned that the unclean condition cannot be replaced. Makes sense. But I'm curious if that really matters? Is there some sort of intrinsic or monetary value if the coins are dirty, or rather in their original state?

 

I have cleaned a few coins and in some cases I can't really tell the difference. For instance, I have a beautiful 1 cent from Singapore 1993 in the best of condition (I'm new at this so can't give you a level, but really it looks like it came right off the production line). This coin I didn't even have to clean, it just glistened right out of the Bundesbank bag which was a surprise to say the least, lol. And not a single blemish. And I have a 5 cent from Zimbabwe 1989 in equally fine condition (also out of the Bundesbank bag), but slightly tarnished. I cleaned it with some metal polish wipes, washed with a bit of hand soap, dried off with a paper towel and it looks as beautiful and new as the 1 cent from Singapore. Now, neither of these coins are worth much of anything regardless of quality from what I can tell. So I'm not really understanding the harm.

 

I really love when the coins are beautiful and shiny like new, they just seem so drab when they are all dirty and tarnished. What do you all feel are the pros and cons and is there anyone else that cleans them?

[KoRnholio]

Collectors prefer coins to be in original/unaltered condition. The damage done to a coin during a cleaning comes in the form of hairline scratches from scrubbing/wiping, or a loss of original surface patina (usually the result of dipping too long). Often times coin newbies will try to turn their brown penny into a "shiny new red one!", which just can't happen without taking the top layer of the coin off, striping it to bare metal.

 

Using a mild soap with warm water and a soft cloth, never scrubbing, is usually fine and won't leave damage. Dipping using chemicals *can* be done without doing much damage, but it still does affect the top layer of the coin. Coins that are dipped too long, or too many times, will look "dead" due to a loss of surface lustre/original skin. These coins are not as desirable as original skinned coins, even though original usually means toning/tarnish that can be a bit unattractive.

[Mark Stilson]

You can never unclean them. And it may surprise you if you look closely with a higher powered magnifying glass seeing scratches. Its a one way street. If a coin has collector value as is and you clean them you can drop the value. Cleaning sometimes is necessary though. Copper coins that have been buried may need cleaning. But most of the time if worth something it involves soaking in mineral oil or olive oil over a long time. And being very careful.

[Arminius]

New collectors at first have to find out what coin surface they personally prefer and what has to be done to get there.

Not all layers are dirt. A patinated surface protects the metal and may increase the desirability and value of a coin. Green powders on base metals may be bronze disease and will destroy the coin sooner or later.

So you need own experience and you certainly will produce some overcleaned or cleaned-to-dead coins you will later remember regretfully.

 

You may strip an old coin down to the metal and get an ugly, porous "slug" or a better surface showing more details. But if you carefully brush the sand off til you get a nice "sand patina" you may be satisfied without the danger of nonreversible damage.

 

Cleaning discussions here may help but own experience with cheap duplicates are essential.

 

As a general orientation:

Avoid cleaning silver and EF to UNC coins mechanically.

Avoid cleaning base metals chemically.

 

[Steve D'Ippolito]

My attitude is much more cautious: just don't do it. Encrusted crud caked onto the coin, as opposed to stuff that happened to the metal, can be cleaned in principle, but I'd want to find out how to do it before even starting. If it's just so ugly you cannot resist doing something, take it to a coin shop and if it's truly advisable they might give you some advice once they have seen the coin.

 

Of course if the coin is something that cost you next to nothing, it doesn't really matter.

 

Meanwhile you are discovering why coins that have the "new" look _naturally_ are so much more expensive--you are not the only one who wants them more. The premium for a red copper coin as opposed to red-brown or brown can be staggering. But you will eventually discover that some types of toning on copper, and especially silver can be spectacular.

 

I was floored to discover the other day as I took down an exhibit in Pittsburgh, that an "ugly black" but otherwise proof-like Russo-Polish silver coin of mine, when looked at from just the right angle, with the light hitting it so that you see the reflection of the light source... has a fantastic cobalt blue color over all of its fields that some collectors will pay gigantic $$ for when it shows up more easily (and on a US coin!). I was pestering other exhibitors showing them like I was some neophyte. Wish I could figure out how to photograph it.

[uncle]

I have an 1865 two cent coin that appears to have very nice detail (the "we" is still intact), but there is a fair amount of verdigris on both sides. I'd like to remove the verdigris but not damage the coin. Suggestions?

[Moonlight Sonata]

Thank you for all the great responses!

 

KoRnholio - I was looking through your collection on OmniCoin (very nice by the way) and I see what you mean by the patina being sought and preferred in some cases - some, such as the rainbow patina, are really quite beautiful. So I'll refrain from cleaning for a while until I'm sure the coin I have is both worthless and truly worth cleaning.

 

I'm also curious how/if the verdigris can be removed, I have a few coins with that. I did read that you should always wash your hands after handling it as it has poisonous components.

[Arminius]

I have an 1865 two cent coin that appears to have very nice detail (the "we" is still intact), but there is a fair amount of verdigris on both sides. I'd like to remove the verdigris but not damage the coin. Suggestions?

 

Verdigris is soluble in hot water. So (multiple) boiling-scrubbing circles in water plus detergents may even solve old dirt/verdigris mixtures.

You have to investigate the coin surface after each cleaning step. If you are lucky the verdigris (oxidized bronze material) is not from the same coin but from it´s former neighbourhood. Otherwise you may find a more or less porous / corroded surface below as on the obverse r. of this 10 Lepta specimen:

 

 

(I stopped cleaning at this state to avoid further damage.)

[uncle]

Thanks for the info. I'll try hot water and dish soap. I have a small bottle of VerdiCare, supposed to be very gentle at removing verdigris with just a soak. I don't want to damage what's beneath the green. It may not be that bad, as the details are still visible, even the normally worn "we" is prevalent.

[just carl]

Using a mild soap with warm water and a soft cloth, never scrubbing, is usually fine and won't leave damage. Dipping using chemicals *can* be done without doing much damage, but it still does affect the top layer of the coin. 

 

This is one of the worst suggestions people make for so called no harm done cleaning. Never, ever clean coins with soap and water. The reasons are simple.

ALL soaps are different. Some are acidic, some are abrasive, some are full of almost anything not intended for metals. Example many dish soaps will discolor coins. Lava soap is so abrasive it is used to clean tar.

Water too is excessively different. Tap water could contain Chlorine, Salts, Flourine, rust from pipes, Lead from old Lead pipes and on and on with almost anything. Tap water in many houses is run t hrough a water softener which adds NaCl to the water. Well water contains almost anything on Earth. Spring water too is similar to Well water.

DO NOT USE SOAP AND WATER ON COINS.