Need some advice on cleaning some coins

I thought you were a chemist? I find it facinating that you believe the chlorine ion in aqueous solution is perfectly happy and that it will not attack metal. I work in the metalworking fluid industry (14 years) and I've seen more metal corroded by free chlorine ions than you can ever imagine. We routinely test for anions in our fluid because it is such a huge problem in industry. I've also examined thousands of corroded parts with SEM-EDXRF and found traces of chlorine.....this after analyzing the customers fluids and finding excessive levels of chloride ion in them. We also have an accelerated corrosion test to evaluate our anti-corrosion packages, the test uses a SALT SPRAY....it will KILL unprotected metal in a day or two.

I certainly do not need to check my inorganic books because you are 100% wrong about chloride ion. I suggest you simply use google and search chloride corrosion.

 

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This simply isn't true.

What is true is that any coin that appears cleaned to a professional or advanced collector has lost much of its numismatic value. If a coin "needs cleaning" it will usually bring at least a little less because you can't be 100% certain that the coin is OK underneath the dirt.

Beginners need to learn what an improperly cleaned coin looks like. Frequently just knowing that bad cleaning will cause the high spots to be the same color as the rest of the coin is a big step in this education. Learn to identify the high spots and compare them to the coin. The more metal that has been removed to cause this homogenous coloration the more damage has been done to the coin. But there can be subtle damage from bad cleaning as well such as hair lines and a dipped out look.

Collectors shouldn't be in a hurrry to learn how to clean coins but they should learn or they'll be paying too much for cleaned coins or selling dirty coins for less than they are worth.

Until a collector knows how to clean properly he shouldn't even consider cleaning a collector coin. Neophytes and those who inherit coins should be warned to leave them be or they'll take out a brillo pad to a nice original patina. This is very common. Coins often walk into coin shops that were shined up by the heirs to get a better price. Leaving them alone is the best advice but collectors will learn when this doesn't apply and know the proper procedure for breaking this rule of thumb even if that means spending money on professional conservation.

 

Ive cleaned every silver coin i own with an eraser and all cleaned up as good as any coin ive seen posted here.
I buy the wide eraser not the pencil type as you could strike the coin with the metal. Has anyone here tried this method.?Copper and other metals dont clean as well using this method.
I suggest before anyone says it wont work try it first even if its an old coin you care little for.

 

I have seen eraser cleaned silver coins sir, and an experienced collector can tell, but the worst part is this area will be extremely noticable in a few years. Just going from experience you will seriously regret ever cleaning a silver coin with an eraser. I would lay whatever little reputation I have on this board on that statement.

Not trying to be a downer, but cleaning with an eraser is an extraordinarily bad idea. The reason I know this is I ruined a few old silver dollars I inherited when I was 8. It looked "pretty" at the time, by the time I was 12 they were very noticable and ugly, and in 1979 during the silver boom I sold them and hoped to never think of how I ruined these coins again. So I know personally its a bad idea.

Chris

 

I would like to know from one of the experts if a simple pat with some rubbing alcohol using a micro cloth could damage silver coins and would a coin be rejected as being cleaned doing this. Acetone has a bit to it that rubbing alcohol doesn't.
I can respect the comments about leaving coins as they are, but I do see problems by leaving someone else's residue from there bare hands on them prior to putting them in a plastic holder.

 

I don't understand what you're trying to say here. Are you thinking that acetone is harsher and more likely to damage coins? It really isn't. On the other hand, I wouldn't be surprised if acetone would attack microfiber.

If you wipe at all, with anything, you're likely to lose the game. If you pat, and you're lucky, you may be okay.

 

I know it's not easy but we want to get away from labels. We want to look at the coins more and lean on the labels less. That's how we collect coins our eyes are truly happy with.

 

I understand, these 3 things and nothing else, but has anyone ever tried denatured alcohol? I have heard of this but have never tried it.

 

I use denatured alcohol but can't swear by it.

It's a cheaper alternative but I don't have enough experience with it yet to recommend it.

 

I spent a few more hours researching this topic and denatured alcohol seems to be the only thing that doesn't penetrate a coins surface. A few other methods always used denatured alcohol as a last step to remove distilled water from the surface thus preventing water spotting.

 

I have never had a water spot on a coin with distilled water. I do three baths, the first gets most everything off the coin, and the second two are to clean the first baths water off the coin. If you get water spots on a coin, isn't that proving you did not remove all contaminants from the water bath? I would want to see water spots if chemicals were not removed, so I know I need further baths in distilled water.

I prefer my alcohol in a glass, not on coins.

Chris

 

Wow, people are really in love (or hate) with cleaning coins. In the case of many ancient coins that are encased in crud, cleaning is necessary. In the case of proof coins or MS60 and up coins, cleaning would probably do more harm than good. The middle grades are where people seem to disagree. Pure solvents are unlikely to cause any problems, abrasion (rubbing) seems to be the real bad boy. Now, which pure solvents offer the most hope. In general there are two kinds of solvents, polar like water and alcohols and non-polar like xylene. Each has benefits. Non-polar solvents like xylene, lighter fluid, kerosene will remove grease and,in some cases, plastic gunk. Polar solvents like water and pure alcohol will remove salty type materials. Acetone is just in-between, polar, but not too polar. Alcohols are not all the same. Rubbing alcohol is available in three strengths that I have seen, 50%, 70% and 91%. The 91% seems to leave the least residue, but especially the 50% might have some wierd additives. Denatured alcohol is grain alcohol with additives that will make you sick if you drink it. Two of the most popular additives are gasoline or fingernail polish remover. All of the alcohols are poisonous and you should not drink them, it's just that grain alcohol can take years to do it. The presence of salts in water can make it more corrosive, either through increased conductivity (corrosion is driven by conductivity) or some other mechanism. The safest way is not to clean coins, but if you are determined to, a mild soap and water wash with no rubbing followed by a distilled water rinse and a final acetone treatment and pat dry is not going to hurt anything and I don't think it would be detectable as "harsh cleaning". Specialized problems would call for specialized treatment.

 

And in 2005 you said:

Howdy knowtracks - Welcome to the Forum !!

You'll likely get varied responses to this question - but in my opinion a coin not ever be cleaned except to remove contaminants that will cause more damage than if they were not removed.

As for what chemicals - in my opinion there are none. ​

Read more: http://www.cointalk.com/t4600/#ixzz1ewrteDf6

So you have changed a bit. I think any pure solvent that will evaporate would be OK for cleaning, although as to how good a cleaning job it will do is still open to question.

 

You are absolutely right and I was just using the old post I saw to yank your chain. No offense, I have the greatest respect for your expertise.

 

One has to decide which is worse for a coin:

residue from someones hands on a coin
or
the residue from a solvent such as acetone

If I knew the answer to this question then deciding what to do would be easy.

 

But see Doug?.....you just confuse people with cleaned and harshly cleaned....just give in and use "conserve" and you life will be a LOT easier. When folks hear "cleaned", they automatically relate that to "problem".

Cleaned = market unacceptable
Conserved = market acceptable

Simple...no more explainations.