Author Topic: Conservation and cleaning of modern coins  (Read 17557 times)

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Offline bruce61813

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Conservation and cleaning of modern coins
« on: June 07, 2012, 06:06:54 PM »
First round - All three coins are from pocket change, so they have plenty of wear on them.

Coins #1 and #3 were first scrubbed using a battery powered Dremel rotary tool. Why battery powered? It has lower torque and top end RPM of 10,000. You can stall it with your fingers. A paste of liquid soap and bi-carbonate of soda was used. then the coins were rinsed and buffed with a very soft brass cup brush used on the dremel. This produced a high shine, but no visable scratching.

Coin #2 was buffed with the brass brush.

The soap paste can be used with a denture brush to remove surface grim and oxides from coins.


Bruce

Offline bruce61813

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Re: Conservation and cleaning of modern coins
« Reply #1 on: June 10, 2012, 05:52:37 PM »
Here is a start: This should work for all metals, it will remove all surface toning, and make the coins shine.

Modern coins that just need a bit of shine [if that is to your inclination].
1. Make a simple paste of liquid soap and bi-carbonate of soda. It should be about the consistency of toothpaste.
2. Here i had to use my Dremel with a very soft brass cup brush, the severe corrosion could be removed by chemical brass cleaner
3. Rubbed with more paste, washed and waxed. You can still see the scars from the corrosion, but to the eye it is barely notable.

If no corrosion , then step 1 and 3 are only needed.

Bruce
« Last Edit: June 11, 2012, 12:15:38 AM by Figleaf »

Offline Alan Glasser

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Re: Conservation and cleaning of modern coins
« Reply #2 on: June 26, 2012, 01:49:22 AM »
I guess it doesn't matter much on modern coins minted in the millions, but I believe a paste of bicarbonate of soda (baking soda) is abrasive and will leave hairline scratches. I think it should be pointed out to new people reading this that this method should never be used on truly collectable, scarce or historic coins, nor those with collector value.   

Offline bruce61813

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Re: Conservation and cleaning of modern coins
« Reply #3 on: July 07, 2012, 07:06:57 AM »
It would take at least 100x magnification to see the any scratches, as the bi-carbonate in a liquid soap would not show visible scratches.

You would never need to clean an new coin right from the mint. If it has been in circulation, then it is already scratched. ancients have enough problems, baking soda won't hurt them.

Bruce

Offline parthaadhicary

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Re: Conservation and cleaning of modern coins
« Reply #4 on: September 21, 2012, 05:01:56 PM »
I am new to coin collecting. I am told that collectors do not clean coins since it reduces its collectable value. Is that true?

Partha

Offline Figleaf

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Re: Conservation and cleaning of modern coins
« Reply #5 on: September 21, 2012, 05:14:04 PM »
No. You should not clean coins unnecessarily. You should clean coins you want to clean for your own reasons, but you should always make sure you know what you are doing. That's what this board is for. Look around on this board for more info, especially when it comes from Bruce, who is our in-house coin-cleaning guru.

The no-cleaning myth is a US invention. My take is that it serves, alongside the "grading is a science" myth, to increase the profits of the third party graders.

Peter
An unidentified coin is a piece of metal. An identified coin is a piece of history.

paisepagal

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Re: Conservation and cleaning of modern coins
« Reply #6 on: September 21, 2012, 05:27:50 PM »
First off, I'm pretty amazed by the results Bruce posted. I don't want to get into American vs european (because im neither) notions of cleaning coins.
I just go by the simple logic if I pay a significant amount for a specific coin, I would wait for a genuine unc un-cleaned coin even if a cleaned one was ready for the taking. After all, I should get the best value for my money. And should the need ever arise that I need to sell the coins, it's a safer  bet with the genuine untouched coins. After all, if I have that particular standard, why shouldn't the next guy.
If you do find someone ready to pay big moolah for cleaned stuff, you've found yourself a bhakra  ;D
That said, if you just want to clean the coins for show-and-tell , and you are least concerned what you can sell them for, go right ahead and start buffing  ;D

Offline bruce61813

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Re: Conservation and cleaning of modern coins
« Reply #7 on: September 22, 2012, 07:09:23 PM »
For new coins in "un-circulated " condition, there should be no cleaning needed. If the possibility of finger prints on silver exists, then try something like Ren Wax, it should take the finger oils off, and protect the coin surface. If the finger prints are visible, then then everything changes. But if that is a concern, the question is why were the coins being handled.  >:D

My examples were what could be done with common change, you never know what will show up. But the simple answer, do as little as possible. If they are intended for re-sale, leave them alone, except in the case of corrosion that may continue damaging the coin unless you do something.

Bruce

Offline mlvs

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Re: Conservation and cleaning of modern coins
« Reply #8 on: January 07, 2013, 07:43:37 AM »
Hi

For cleaning coins, One of the dealer asked me to soak the coin for a minute in Harpic(Toilet cleaner in India :)) and wash thoroughly with Sabeena (Dish washer).
Will it cause any damage to my coin?
Can I use used/old tooth brush for cleaning coins?

akona20

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Re: Conservation and cleaning of modern coins
« Reply #9 on: January 07, 2013, 10:18:51 AM »
Yes Harpic will cause damage but an old toothbrush may at times be okay.

What coins are you looking at cleaning?

Offline mlvs

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Re: Conservation and cleaning of modern coins
« Reply #10 on: January 07, 2013, 10:55:19 AM »
Nickel Brass ( 1 Naya paisa India 1963 ) and few copper coins

akona20

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Re: Conservation and cleaning of modern coins
« Reply #11 on: January 07, 2013, 11:05:35 AM »
Perhaps best left uncleaned

Offline mlvs

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Re: Conservation and cleaning of modern coins
« Reply #12 on: January 08, 2013, 06:41:21 AM »
Thanks Akona. But i bought the coin with some stains on that. Was afraid it might be some chemicals and would destory the coin.

Offline Figleaf

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Re: Conservation and cleaning of modern coins
« Reply #13 on: January 08, 2013, 03:24:44 PM »
Stains on nickel-brass are likely caused by chemicals, as it is a fairly stable alloy, but the chemicals (likely acids) are likely to have been used up on the metal a long time ago. Indeed, you may be able to remove the spots with the recipes given upthread by Bruce, but keep in mind that patina will be lost and it will take many, many years before it is restored. Your choice.

Peter
An unidentified coin is a piece of metal. An identified coin is a piece of history.

Offline bruce61813

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Re: Conservation and cleaning of modern coins
« Reply #14 on: January 08, 2013, 03:50:14 PM »
As Fig pointed out, the less you do to a coin the better. Stains on the coin metal are hard to deal with, but, you can try a paste of sodium bi-carbonate [baking soda] and dish washing liquid. This is non-acid and, and more of a polish. Just apply it and rub. You want a thick paste, just barely liquid.


Bruce