Coin cleaning. An acceptable way?

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100% yes. The dirt on the coin bugs me. If it were anything other than a coin I would have cleaned it off already. So my only hesitation in doing so with the coin is all of the material I've read suggesting you should never do it. And going back to my OP, I was looking to clarify if that was a hard and fast rule, or if the literature was referring to cleaning that might alter the coin's raw surface material.

 

Both

 

In numismatics, originality is more important than dirt. That's the thing which new collectors have trouble with, for some reason. You just_don't_touch_the_coin. That's all.

Here's one practical reason: Coins don't get dirty evenly. Circulation allows dirt to accumulate in tighter areas, while more open areas get wiped by handling and stay relatively clean. Now, the same is also true of the tarnishing/toning process, although not at the same rate.

A dirty coin does not tone where it's dirty. Yet, the rest of the coin will acquire patina over time. When you clean off the grime, it exposes untoned surfaces. The result will be a splotchy coin with plainly-altered surfaces.

It's not difficult to clean a coin without physically damaging it. The unspoken standard is, frankly, if you can clean it so the experts can't tell it's been cleaned, you can clean it.

 

What he said, absolutely.

 

While you don't want to "clean" a coin, you may want to conserve it. But conservation is about removing contaminants from the coin as well as neutralizing and stabilizing corrosion, especially before TPG submission or other long-term storage. While conservation is not about improving the appearance of a coin, sometimes the appearance of a coin is improved by conservation.

Having said that, sometimes coins are just dirty beyond what is reasonable to leave on the coin for originality. In other words, there are beautiful crusty original coins, and then there are coins that just have dirt on them. Knowing the difference is important. It's rare, but sometimes you see slabbed coins that are slabbed with dirt that obscures the coin, where soaking the dirt off would not be detrimental.

This, for example, should have been soaked before slabbing. It's only going to harm the coin by leaving an encrustation like that on there, especially if it flakes off and starts bouncing around in the slab.

 

This is all great information. Thank you to everyone for your contributions. I feel well informed now! Cheers.

 

I agree with most of the sentiment here, and if I can read into the argument a little, I agree that originality is right up there in importance with wear when putting a value on a coin. Further, the decision to properly conserve a coin should take into consideration the market for the coin, and the reason for cleaning.

However, I disagree with the overly broad statements, like 'just don't touch the coin', and cleaning dirt will 'result in a splotchy coin with plainly-altered surfaces'. I disagree with these broad statements based on my admittedly narrow focus on late date large cents.

For these coins, it's often necessary to remove dirt and grime because it builds up in the same area that often contain the attribution points for variety identification. If the grime is not removed, you can not attribute the coin. Further, in the majority of cases the slightly different tone found underneath the dirt/grime is of very little difference, and the newly cleaned portion of the surface will tone quickly into a uniform, natural patina. You are not altering the surface of these coins by using water and xylene, you are merely dissolving the organic compounds attached to the surface, but with the risk of scratching the coins and possible putting your health at risk with the exposure to xylene. Additionally, as copper is a very corrosive metal, leaving organic compounds on the surface of a coin will over time cause damage to the metal. So I consider removal to be an appropriate and often necessary conservation step, not done for aesthetic purposes but done for preservation and numismatic reasons.

I know if I had to provide a blanket statement about cleaning coins I would give the standard 'Coins should not be cleaned'. However, there is a more nuanced take on the subject that involves your skill with conservation, why it's being done, and how will the potential market for this coin view conservation techniques, etc. These are all things that beginners just do not understand, but those with more experience may come to the conclusion that the trade offs of leaving the coin as found versus properly conserving the coin side with cleaning.

 

REALLY! If you don't enjoy it, why do it?

 

If you want to remove dirt without harming the surface, the primary thing to remember is: Don't rub the surface with anything hard - which could include pencil erasers, towels or cotton swabs. Second: Don't use any agents that will react with the coin material. That being said, here is something that might work for you: Place the coin in a sink (if you wish, on a cloth to protect it) in a way that the stream of running water will contact the coin. Run hot water over the coin for several seconds up to a minute or so, you can turn the coin and repeat. After turning the water off, pick the coin up by the edges and lay it on a soft towel. Fold the towel over and blot the coin without rubbing. Stop.

 

And this is where beginners run into trouble.

Water seems like it would be fine, but what's in your water? Are you on city water? Well water? Has fluoride or other substances been added to your water? Is your well running low and sending up bare bits of sediment and other fun stuff? (yes, I have had that). All these things will be left on the coin if you run water from the tap over it, and eventually the contaminants can harm it.

If you want to use water, use distilled.

 

So in reading everyone's posts, the only way to clean a coin is...........not to !

 

Everclear. Just don't drink it after.

 

The only thing I'd add to Doug's words is that distilled water is not required if your final rinse is (as it should always be) acetone. Acetone will remove any deposits from the water - which won't be touching the coin long enough to matter - and allow you to use tap water under pressure, which will help with forcing contaminants off of the water. In fact, that's how I dip - the coin goes instantly under warm running water to more quickly blast the dip off of the coin.

Acetone and xylene are differing chemicals for similar situations. Acetone is a polar solvent and xylene nonpolar; they are best with differing potential contaminants on a coin. Acetone is usually the better but if it won't touch what's on the coin, xylene might work.

 

Dipping as Doug said should only be done if one is experienced enough to do it and just as important having an idea of if it will help the coin . One way is to buy a roll of silver dimes or coins with just melt value and experiment . I started using dip at full strength and the outcome wasn't the best , now I recommend a diluted dip of at least 25% dip 75% distilled water , as it's weaker and one will have more time to react to unforeseen changes. Also remember dips contain acid and will always remove a layer from the coins surface . Too much or even a few seconds too long will remove any luster a coin has so practice and then practice some more . Copper should never be dipped unless you like pink coins . Also never dip a circulated coin .

 

The thing you need to know about dipping is, it physically strips a layer of metal off of the coin, never to return. That's how dip removes toning - it removes it. One can only remove so much metal - so many layers of molecules - before the coin no longer has the microscopic roughness which causes "luster." Such a coin is referred to as "overdipped," and once you've seen one you'll know forever what they look like. They look destroyed, because they are. Lifeless. The detail is there, the coin is obviously Mint State, but has the dull finish of an EF-AU50.

And here's the kicker: the damage is cumulative over the life of the coin, and no two coins are the same. Strikes differ, planchets differ, and two identical coins will differ in the total immersion time in dip they will tolerate before being ruined forever. And you will not know that limit has been reached - there is no prior sign - until you've killed the coin.

I therefore cannot offer a hard number regarding how long you can dip a given coin. I_can_say that you'll be very lucky if it exceeds ten seconds' total immersion in full-strength thiourea (diluting it gives you more time, but not in linear fashion, and it slows the production of results). The trouble is, you cannot ever know how much of that has been used up by a previous owner.

That's why dipping is a crapshoot.

 

OMG!

Guys, I know this is fun but there are going to be a beginner who takes this to heart. IMO, let's put a when we are entertaining the "regulars."

 

Best idea; however, can be expensive and depends on the actual coin and its value. There are some coins that a conservation service cannot really improve much but they may take your money if they decide to tackle the job.