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Author Topic: How to Clean Silver (not Silvered) Coins  (Read 72794 times)

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Offline Joe Sermarini

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How to Clean Silver (not Silvered) Coins
« on: January 20, 2005, 11:43:01 pm »
Discuss methods for cleaning silver coins (that is solid silver, not plated or coated coins) here.  If you have questions about a specific coin, please start a new topic.  
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Offline Blindado

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Re:How to Clean Silver (not Silvered) Coins
« Reply #1 on: February 10, 2005, 12:46:22 pm »
The artists among you will doubtless cringe, but I have had great success cleaning most coins, including silver, coated with really tough crud using naval jelly rust remover, bought at my local auto parts store.  (Do NOT, however, apply to silvered coins, or they won't be any longer.)  Often, the results of a 15-minute soak can be wiped away with a rag after rinsing--repeat as necessary.  A brass brush or other tool can be emplyed as needed.  I bought this Macrinus denarius for $2 from a junk bowl, with no idea what it was but just enough visual clues that I thought it probably wasn't yet another FEL TEMP.  Naval jelly did the trick.


Offline Robert_Brenchley

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Re: How to Clean Silver (not Silvered) Coins
« Reply #2 on: October 20, 2005, 04:51:03 pm »
Try boiling in washing soda and brushing.
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Offline wolfgang336

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Re: How to Clean Silver (not Silvered) Coins
« Reply #3 on: December 04, 2005, 02:14:34 pm »
Much!  :) If the ammonia soaks are working, I'd stick with them, and try to work out the grime with a pin and a light touch. If that absolutely fails, dilute some lemon water (half and half?) and soak for a few minutes at a time until the desired level of cleanliness is achieved.

Evan

Andrew Courtney

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Re: How to Clean Silver (not Silvered) Coins
« Reply #4 on: May 10, 2006, 02:36:23 pm »
I have just started trying to use a art gum eraser, the very soft kind used for drafting.  I have been using it before using a brush and after a lemon juice soak.

So far, so good.  It seems to be removing the crud real well without damaging the coin.  I am still in early stages with this coin.  Has anyone tried this and run into any problems?

Miguel Diaz

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Re: How to Clean Silver (not Silvered) Coins
« Reply #5 on: May 19, 2006, 07:25:34 am »
I've used 2-3 times acid formic to remove green on Antonines denarii.

After some seconds, green is removed ... Then you must place the coin in distilled water to stop the acid.

Green is removed. If coin contains a significant proportion of copper, he will be darker, with a pretty good patina and spot where green was will be a little lighter than the rest of the coin.

If coin has a lot of silver, then the spot where green was will be darker or black like normal silver oxydation.

My method work with coins with silver, a lot of content of silver.

Miguel Diaz

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Re: How to Clean Silver (not Silvered) Coins
« Reply #6 on: May 19, 2006, 07:28:17 am »
I've heard that some green could come from reaction of plastic. And that acetone could remove it. I will try this one of these days to verify this ...

bruce61813

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Re: How to Clean Silver (not Silvered) Coins
« Reply #7 on: May 19, 2006, 03:07:33 pm »
A note about "Horn Silver". Horn silver is a silver chloride compund, tha tis formed in a similar fasion to tinchloride in Bronze Disease. You could call it silver disease. It is not water soulable and hard to treat, but like BD, it will ruin good coins.

   The best method I have found for it, and the simplist, is the use of photographic fixer.
Most fixers are based on the thiosulfate ion, especially ammonium thiosulfate. Up until the 1970s, sodium thiosulfate or 'hypo' was the commonly used fixer. Both fixers work best in acid conditions and this is usually created using small quantities of acetic acid. The fixer removes the unexposed silver halide [in this case AgCL or silver chloride] leaving behind the reduced metallic silver. It takes a small amount, and a soak of 30 minutes should be sufficient. Soaking and scrubbing afrewards is recommended, especially the soaking in distilled water, to remove any remaing salts.

Bruce

Offline AdonisRock

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Re: How to Clean Silver (not Silvered) Coins
« Reply #8 on: January 25, 2008, 03:08:35 am »
Any other methods I can try for horn silver?? Photographic fixer may be a bit of a hassle for me to get my hands on.

Offline Robert_Brenchley

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Re: How to Clean Silver (not Silvered) Coins
« Reply #9 on: January 25, 2008, 04:44:14 pm »
Formic acid is seriously nasty, and I wouldn't trust anything so powerful as to take it off in seconds. If you want to use acid, short soaks in white vinegar, interspersed with brushing, will do it slowly and safely.
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Offline AdonisRock

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Re: How to Clean Silver (not Silvered) Coins
« Reply #10 on: January 25, 2008, 06:00:37 pm »
Thanks Robert, that's exactly what I wanted to hear, I'll give the vinegar a go.

E Pinniger

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Re: How to Clean Silver (not Silvered) Coins
« Reply #11 on: March 27, 2008, 04:14:01 pm »
I've found vinegar (spirit vinegar preferably, but other types would probably work) extremely effective at cleaning greenish copper deposits from the  surface of silver coins.
It seems to only dissolve copper compounds, and not silver ones, so it has minimal effect on the toning + patina of silver coins. For the same reason, it's not much good at cleaning very dirty/blackened/crusty silver coins (I use lemon juice for this)

I used this to clean some Victorian and 20th century British silver coins which had been stored in PVC coin album pages for years, and had nasty greenish and yellowish surface deposits; after a few hours soak in vinegar, then a very light scrub with a nylon brush followed with a brief soak in distilled water, they were completely transformed - all the green had disappeared, but as the surface toning of the silver was not affected, they did not have a "stripped" or "over-cleaned" look.

As I said, this probably won't be much good for dirty silver ancients straight out of the ground, but if you have any silver coins which have gone green due to being stored poorly, a soak in vinegar should do the trick.
It should be OK on base silver/billon; many of the British coins I cleaned were 50% fine silver (post-1920). I'd be careful with silvered/fouree coins though.

Offline SRukke

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Re: How to Clean Silver (not Silvered) Coins
« Reply #12 on: June 08, 2009, 11:55:30 pm »
Can someone supply a decent picture of what horn silver looks like. Never seen it and would like to know it if I run across it.

Offline SRukke

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Re: How to Clean Silver (not Silvered) Coins
« Reply #13 on: June 09, 2009, 07:49:35 am »
So on a couple silver republicans I have a small amount of a black very hard substance. Not easily removed. Is this horn silver? What is the best way to remove it on these coins.

Sri_Sahi

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Re: How to Clean Silver (not Silvered) Coins
« Reply #14 on: June 09, 2009, 02:42:13 pm »
So on a couple silver republicans I have a small amount of a black very hard substance. Not easily removed. Is this horn silver? What is the best way to remove it on these coins.

Yes, looks like horn silver. I usually assume that whoever cleaned the coin originally knew what she was doing and stopped where she did for a reason. I wouldn't take a chance with a coin that looks OK as is. As I understand it, horn silver is actually relatively soft. The name derives from the fact that it can be cut with a knife, like animal horn. 

Nick K

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Re: How to Clean Silver (not Silvered) Coins
« Reply #15 on: June 14, 2009, 03:16:53 pm »
Hi folks I just got 2 partially cleaned Trajan denarii and I am debating how to proceed with them. I did the initial cleaning and most of the black stuff is gone but as you can see on the picture there are some copper deposits on the surface. I have no clear idea on how to get rid of them so I would greatly appreciate any advice that will help me remove the copepr crust. Thanks in advance!

Offline bruce61813

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Re: How to Clean Silver (not Silvered) Coins
« Reply #16 on: June 14, 2009, 08:28:09 pm »
Nick, you can try 1 tablespoon of lemon juice fully mixed into a cup of olive oil, heat it on a coffee makers hot plate, usually until the mixture turns clear. The acid in the lemon juice will help break the encrustations free from the coins flan, the oil seems to isolate the surface. Lemon juice has little or no affect on silver, but it will  breakdown some oxides.

Bruce
too many coins - too little time!!

Nick K

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Re: How to Clean Silver (not Silvered) Coins
« Reply #17 on: June 15, 2009, 05:41:52 pm »
Hi Bruce,

Sounds like a good idea. The copper encrustations look like they are firmly attached to the coins so I assume it will be very hard to get rid of them unfortunately. I hope since the metal of the coins is good no pitting will occur when I hit them with the lemon juice/oil mix. Thanks again for the advice!

Offline Danny S. Jones

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Re: How to Clean Silver (not Silvered) Coins
« Reply #18 on: August 08, 2009, 12:40:26 am »
What about the flaking of silver from coins? Is this a result of normal factors or the corrosive forces of horn silver?

Offline bruce61813

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Re: How to Clean Silver (not Silvered) Coins
« Reply #19 on: August 08, 2009, 03:50:25 pm »
I have not encountered silver flaking from solid silver coins, but it is common in silvered coins. It may be possible that solid coins with an improperly mixed allow of copper & silver may develop layers of hard & soft. these might flake off, if corrosion eats away a softer layer. This is what occurs with 'silvered' coins. The later between the silver and the copper oxidizes and the silvering peels away..

Horn silver is a different matter. From most appearances, it is more of a gray blob, and fairly hard. It is AgCL - silver chloride, and is the same type of reaction as Bronze Disease is to the Copper + tin in the bronze. The difference is the Silver +copper allow is being attacked by the  HCl formed by the chlorides.

Bruce
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Offline Danny S. Jones

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Re: How to Clean Silver (not Silvered) Coins
« Reply #20 on: August 09, 2009, 03:29:08 am »
What about the flaking of silver from coins? Is this a result of normal factors or the corrosive forces of horn silver?

This is the flaking I'm talking about...

Offline areich

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Re: How to Clean Silver (not Silvered) Coins
« Reply #21 on: August 09, 2009, 07:46:14 am »
I see what is usually called 'lamination defects' but flaking is as good a word as any,
though in this case it isn't flaking but has already flaked off.

Andreas Reich

Offline Danny S. Jones

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Re: How to Clean Silver (not Silvered) Coins
« Reply #22 on: August 09, 2009, 12:16:27 pm »
The coin pictured above is solid, not a fouree or silvered AE. There has been flakes of the top layer of silver that have come off, but in it's present condition, it doesn't seem brittle or show evidence that more will flake off. Though I wonder how to care for this coin, to avoid any more of the silver coming off.

I see what is usually called 'lamination defects' but flaking is as good a word as any,
though in this case it isn't flaking but has already flaked off.

So, whatever you call it, would this result from corrosion, impurities in the silver, crystallization, or maybe an effect of the striking process?

Offline Britanikus

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Re: How to Clean Silver (not Silvered) Coins
« Reply #23 on: March 30, 2012, 10:24:56 am »
KD,

Ammonia reacts with copper. Most silver is not pure and has some percentage of copper in it; so if you place your coin into a solution that reacts with copper, it should turn green or blue. You can use it to patinate copper (probably coins too, although I have not tried it  :angel:) to the green color that you see on older copper roofs. All you have to do is suspend your copper object over some ammonia in a sealed container until it turns the color you want.

Hope this helps,
Josh
Hi Actually  Ammonia dos not react with copper it reacts only with Lead .Lemon juice reacts with copper .Ammonia is the best way of cleaning silver .

Offline otlichnik

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Re: How to Clean Silver (not Silvered) Coins
« Reply #24 on: April 03, 2012, 03:18:02 am »
Ammonia very clearly DOES react with copper and all copper and zinc alloys.  For example, anhydrous ammonia - which is an extremely dangerous and toxic form of ammonia - will litterally destroy/disintigrate copper and zinc alloys by the action of its fumes alone.

The question - which I can't answer - is whether regular household ammonia, applied in liquid form, will have any detrimental effects on a coin made of a Cu-bearing AR alloy.

Shawn
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