"Must clean" situation

What are the situations when you must clean/conserve a coin? In other words, if you do not do smth. to a coin, it gets only worse?

P.S. It would be great if specific situations are mentioned.

P.P.S. I will summarise here all the situations mentioned in the thread:
- verdigris [link] (be carefull, the author has dangerous humor)
- PVC damage [link]
- ancient coins with centuries of rock hard dirt on them [link1,link2]
- bronze disease of ancient bronzes [link]
- excessive dirt [link]
- such situations do not exist [link]

 

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If whatever the coin has on it is going to further damage the coin...it should be cleaned (conserved). However, it requires proper cleaning. Improper cleaning will only make things worse.

 

If a coin has issues with verdigris, it should be cleaned.

I would recommend a high-grit sandpaper or a brillo pad, followed by a dip in nail polish remover for about 10 minutes.

Then, use an acetylene torch to restore the coins original patina.

 

I wouldn't recommend sarcastic responses to new members. Who knows what their level of knowledge is.

 

NEVER CLEAN A COIN! Even if its the most valuable coin in the world u NEVER, NEVER clean a coin.

 

On your own, no, you shouldn't. But having your coins conserved could be good, but only under certain circumstances

 

NEVER CLEAN A COIN! Conserved is just another name for cleaning that makes some people feel better.

 

These replies always crack me up.

 

There have been many past threads on the subject and mechanism of conserving coins. Conserving practices should not cause any damage to the original metal of the coin. True, "never clean" is a good statement to make to people whose background is not known. Conservation firms employ chemists and archivist people who can spend a large amount of time, removing or stopping damage. Average collectors are impatient, and won't spend the time or effort to develop the chemical and metallurgic knowledge and the physical experience practicing on "beyond conserving" coins, thus they are "cleaning" rather than conserving. Just as grading ability does not not develop after looking at 10 coins, conservation ability doesn't occur after working on 10 scrap coins. Use the search function for subjects with verdigris ( probably the most common), PVC damage, etc.

Cleaning leaves surface damage visible to the experienced grader.
Conservation leaves no surface damage to the experienced grader.

Jim

 

What about PVC damage, corrosion, etc.? Why do people send their coins to NGC? There are some situation when it has to be done, right? These situations are usually briefly mentioned in this forum. I am just trying to summarise those situation for myself.

 

Thanks for the comment, Jim! I searched a lot through the forum. It seems people only mention verdigris and PVC damage. Not much else is mentioned. I just wonder what else can be catastrophic to the coin (except cleaning).

 

Did you mean NCS? An after they clean your coin its put in a NCS holder stating its been cleaned or conserved.

 

Ursus LOL sorry but you have just set this thread up for the weird and wonderful humour that is CT at times
OK how about Nuclear explosions LOL see what I mean
Right lets be seriouse, take ancient coins with them you quite often have to clean them if you purchase them in the raw they can come with centuries of rock hard dirt on them.
These you can soak in olive oil or distilled water, (You can soak for a year changing the solution and softly cleaning with each change)slowly working the crud off with a toothpick or even a rose thorn.
Some folks will go as far as ectrolosis but this can even strip away the patina never mind the rest of the stuff you do want to remove (care required) personaly I like to use a fiberglass pen in different grades
Coins can be re patina'd as well there are chemicals on the market that will do it.
Most modern coins don't touch get expert help if they are of value

 

Thanks, De Orc! I updated the list. (I do not want to ignite the war here, I am just curious when people do clean (sorry, conserve) their coins)

 

Correct, I meant NCS.

 

Well ancient bronzes often have the issue of what's called bronze disease. Basically, the chlorides in the soil the coin was in mix with the moisture in the air to form hydrochloric acid. This results in the coin slowly turning into a fine green powder, and it looks kind of like your coin is growing moldy. This can disintegrate an entire coin over time if left untreated. One really needs to treat such a coin with sodium sesquicarbonate or some other chemical solution to stop this, and it can strip artificial patinas.

 

While certainly coins with bronze disease should be cleaned, the fact remains that almost all ancient coins have been cleaned. The number of ancient coins that spent the last 2000 years in a bank vault or sock drawer approaches zero and the number that were sealed well enough in a pot that there was not even dust on them is not a lot greater. If you are a true believer in the 'never clean a coin' mantra just realize that you can not collect ancient coins. I'm really not sure when in history we start getting enough surviving coins that did not come from the ground that it is possible to be hardcore about untouched surfaces but I know it is after the period of anything I collect so it is not a practical possibility for me to collect with the same mentality that is so obvious with the US market for modern coins. The question is not whether a coin was cleaned but how well it fared in the process. It matters little whether it is raped and raw or caked with so much dirt that it can not be identified. Both are serious faults. In between there is a middle ground. No one alive today will live to see the oldest US coin half the age of the newest hammered coin from the middle ages. Perhaps in another 1700 years modern world and US collectors will understand the problem that ancient collectors know well. Does anyone know how PCGS slabs hold up after a millennium?

 

RICKY YOU ARE REALLY RIGHT... I WILL NEVER NEVER CLEAN MY COIN..MY AVATAR is in great condition now..

 

Here's a link to a thread I started a few days ago. As you can see from the picture, this coin needs to be cleaned.
http://www.cointalk.com/t190203/

There are some coins that you get that are covered in glue, tape resin, soda, marker, or some other substance and if you want to actually see the coin and not the substance, you have to clean them. It may hurt the value, but you either will have a coin you don't want to look at because it's covered in gunk or a coin that is presentable but cleaned. I've had several instances where I found a coin like the one shown above in my dealer's junk bin because no one looked close enough to see what it is.

 

I agree, there are plenty of situations where you would need to clean a coin. That said, the whole idea as far as coin collecting goes is to never buy a problem coin. If you never buy a problem coin then you will never have to clean one. just my two cnts.