how to clean coins without ruining them

Hi,
I noticed that many NGC-graded slabbed coins are labeled "CLEANED". Yes, if a coin has been cleaned (especially abrasively with some sort of chemical detergent), it can be seen.

Coin grading experts can tell if a coin was cleaned.

My idea is to clean very dirty silver coins that have black/dark stain. Then, to let them tarnish and get the yellowish silver tarnish.

But, how I clean the coins without ruining them?

It would be great to clean them and send them in for grading afterwards.
I always heard to not clean them but I still do clean up my junk silver a little. Just an easy wipe down but nothing crazy or abrasive.
I've bought some cleaned coins before, not a deal breaker for me if the price is right.
Some people use baking soda to remove the black stain, I don't know if that's abrasive. Whether the coin graders can see anything under the magnifier glass.
I could use ordinary soap + warm water and just rub with my fingers. Not sure if this is "abrasive".
serial Well-Known Member Silver Stacker

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If you are asking the question, dont! Or at least not on anything important. I have a friend who is an artist at coin restoration. He has cleared many coins for me of debris, gunk, glue, pvc etc before I sent them to get graded. Nothing he touched came back in a body bag. But i have seen many a coin ruined by a novice. Basically the rule is, dont use any sort of friction, dont strip layers if the coin and dont leave residue. You basically want the contamination to fall off the coin. Its some times requires stages eg oil to neutralize the verdigris, acetone to remove the oil, distilled water to cleanse the coin and air blower to quick dry
Thats just an example
Interesting what you're saying.
I once used dishwasher solution and indeed, it did scratch the coins quite heavily. I was amazed, since that's what is used to clean plates. But on coins it leaves scratchmarks, quite visible ones.

Since then I only used soap and my own fingers to rub. Fingers are soft enough, but hard enough to rub. Not sure if this is a good idea, prolly not.

I'd like to research some less abrasive methods to get rid of unwanted dark silver patina and spots etc.
Jason1 Well-Known Member

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There is only one method that wont ruin a grade and its called dipping, needs tobe done by an experienced person using a specially made product. If done wrong it will ruin a coin.
You really cant do any rubbing at all, including using your fingers to rub them.
Some people dont even like dipped coins and prefer them looking old. If you like collectors coins snd hate dirty coins, then You better have deep pockets and buy only mint coins.
Other wise stay away from collector coins if you need shinny coins.
A dirty coin uncleaned would be more valuable than a cleaned coin.
There is no cheat around this other than dipped coin done by a specialist in the field bicarb will be noticed.
Silver will almost certainly tarnish in its life time, people know and understand that so them going dark doesnt hurt value in the numi world.
Only anal novices in the bullion world really care about silver coins looking all shinny as they dont put them under a microscope when buying coins.
On new coins they dont even want you to handle the coins at all to get the best possible grade.
Those ASE reverse proofs released recently, in order for the grader to give the best possible grade, the graders wanted people to send the coin completely factory sealed in its post box.
So people werent even opening the box in order to try and get the best grades let alone touch the coin. So people were paying hundreds of dollars more for unopened boxes and there is a cuttoff date for the coin tobe excepted after the coin was released as well for them to get the best possible grading.
Point is collectors are anal about coins being touched in any way and the surface of a coin.
There is also the added risk of dipped coins going backwards in value.
There are examples of coins where the toning was covering the fact the coin was cleaned many many many years ago, and once it was dipped the damage was revealed and the grading was changed.

Best advice dont touch it, im sure bullion collectors are responsible for ruining a huge amount of coins as they arent numi's. But think they are.
Hence why my self stay away from this numi thing, you really have to know your stuff and the rules are very long, i know this one as its rule number one. Lol after that i know very little lol.
I learnt this rule as a teen i cleaned a coin and ruined it, i did the baking soda and foil trick and washed all its value away and the coin dealer ripped me a new one when i showed the coin i had to get valued. I thiught it looked amazing all cleaned up, to him it was worthless and ruined. Lets say i never did that again and its embarrasing to admit i did such a stupid thing as cleaning a coin.

Last edited: Aug 10, 2020
GF Well-Known Member Silver Stacker

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One of our long time members (RIP Fergo) was kind enough to show me his method. He insisted it wasn't for collector coins but because he liked his stack looking pretty... soak the coins in cloudy ammonia for 48 hours, rinse them in hot water, gently rub with a wet bicarb solution. I have to tell you this is a very satisfying process. I think it's hard to achieve toning that looks natural.
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Jason has expanded on this quite well. To put it bluntly, if you rub the surface of q coun with soapy water and your finger i will be able to tell. You will leave tiny hairlines, any kinetic force will. Dipping coins is a process using special chemicals to remove a layer of the coin. Go to far and you can remove the original surface entirely or expose previously un noticed issues. Toning is a positive depending on how it occurs and the coin issue.
Markco2 Well-Known Member Silver Stacker
Markco2 Well-Known Member Silver Stacker

I first introduced the Cloudy Ammonia and then Bicarb to Fergo about 8 years ago, when he started buying my stack of 66 Rounds. Fergo was a terrific gentleman. Loved trading with him.
Everytime He bought mine, they would go to him sparkling clean. He loved that. That was when he asked me how I did it. His goal was to buy silver for his grandkids.
Was sad to hear that he is no longer with us, when I came back here recently.
We used to have a lot of good conversations.
RIP Fergo

Cheers Markco2
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Perhaps you could invent a gadget to mimic the cleaning action of a pocket on a walking person that cleans coins with a natural patina? I also know from personal experience that inadvertent coins from a washing machine cycle always come out with a healthy sparkle.
wondercrew New Member

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Cleaning silver coins with ammonia is much faster than cleaning coins in citric acid. For cleaning, a solution of ammonia (10% ammonia) from any pharmacy is used. It is convenient to pour it into a small container (5-10 ml.) the main thing is that the coin is completely immersed in the solution. The coin should be turned over in the solution so that both sides are evenly cleaned. But my experience has shown that it is better to use a special machine for cleaning silver from aliexpress.
Plastic container with hot water. Add 1 teaspoon of baking soda 1 teaspoon of salt and stir to dissolve. Add a piece of aluminium foil so it enters the water and folds up over the edge of the container. Add your silver to the liquid so a part of it is protruding - don't let it touch the aluminium foil. Connect the positive terminal of a 9V battery (small alligator clip leads do the trick) to the aluminium foil and touch the negative lead to the silver item. Invert your silver when you want to clean that part of it and repeat. Clean thoroughly with water to remove salts.
Don't get the battery polarity wrong or you will strip the silver from your item!
Silver is such a soft metal that pretty much anything will scratch or scuff it in some way.
I've used spectacles lens cleaner and a soft cleaning cloth, on a proof gold coin with finger prints, and it looked perfect.
Using any detergent might turn the coin into a pale "washed" coin and the entire value of the coin is affected. Many people don't know how much washing can affect a coin, so they keep washing them with soap and dish detergent.
SlyGuy Active Member

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If you want good-looking coins, buy gold. Buy 917 gold and it stays good or great looking for longer than you will just in plastic flip cases. 999 gold is fine but will scratch a bit if you don't keep it from contacting other coins. You don't even need capsules, though.
For silver, there is no good way. I use a microfiber cleaning cloth for handling my coins and lightly rub the fingerprints off my big 5oz ATB coins set... then store all my 1oz and 5oz silver in capsules. Still, it's silver... it tarnishes naturally. There is no easy answer.
sammysilver Well-Known Member Silver Stacker

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You can get dirt of junk coins with warm soapy water. This leaves no scratches at all. You can also put them in the dishwasher.