FORVM`s Classical Numismatics Discussion Board

Numismatic and History Discussions => Uncleaned Ancient Coin Discussion => Topic started by: Joe Sermarini on January 20, 2005, 11:43:01 pm

Title: How to Clean Silver (not Silvered) Coins
Post by: Joe Sermarini 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.  
Title: Re:How to Clean Silver (not Silvered) Coins
Post by: Blindado 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.

Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Robert_Brenchley on October 20, 2005, 04:51:03 pm
Try boiling in washing soda and brushing.
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: wolfgang336 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
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Andrew Courtney 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?
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Miguel Diaz 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.
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Miguel Diaz 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 ...
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: bruce61813 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
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: AdonisRock 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.
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Robert_Brenchley 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.
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: AdonisRock 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.
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: E Pinniger 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.
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: SRukke 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.
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: SRukke 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.
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Sri_Sahi 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. 
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Nick K 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!
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: bruce61813 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
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Nick K 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!
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Danny S. Jones 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?
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: bruce61813 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
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Danny S. Jones 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...
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: areich 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.

Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Danny S. Jones 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?
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Britanikus 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 .
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: otlichnik 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
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Platon on October 13, 2012, 09:52:22 pm
Is this horn silver on the reverse of this coin? Any thoughts on the look of this coin--maybe it's over-cleaned? It looks really shiny compared to most silver coins I've seen on this website.

I didn't clean this coin myself, I like it very much because of the crisp portrait, but perhaps whoever cleaned it didn't do the best job?
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: SRukke on October 13, 2012, 10:41:57 pm
I don't think it's horn silver. Looks more like rust. Maybe the coin may have been buried with something made of iron?
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Platon on October 13, 2012, 11:00:50 pm
Should I treat the coin any way? Any sense in trying to remove it?
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: daverino on October 14, 2012, 06:19:45 pm
It does look like a rust stain. Personally, I would try lemon juice which is generally safe to use on "good" silver coins. It contains citric acid which specifically binds to iron and can dissolve iron oxide. I would see if working on the stained area with a soaked q-tip can lift or lighten the stain but wouldn't be too disappointed if it doesn't since it is a fine looking coin either way.

Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Holding_History on October 20, 2012, 08:57:01 pm
I just finished cleaning a silver coin covered with some of the hardest crud I have seen before. I used vinegar and lemon juice (at different times), a straight pin to take the top layer off, stopping before I got to the metal so as not to scratch the coin, then as I got closer a nylon brush and paper towel.

Nathan
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: otlichnik on October 24, 2012, 04:34:52 am
Wow!  Incredible job Nathan.

I could actually have lived with the coin as it was before too as it was interesting, but there is no denying that you have brought out excellent detail from under that stuff.  And very interesting "stuff" too.  So green it would seem to have been hoarded with some Cu coins.  I know there was significant Cu in the alloy when Quietus coins were being struck but I don't think that amount alone would account for that green.

Shawn

Title: Re: How to Clean Silver (not Silvered) Coins
Post by: ionutbd on October 24, 2012, 08:46:58 am
Is rather a billon coin than a silver one, but great job cleaning it. Wel done!
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Britanikus on January 08, 2013, 02:36:02 pm
 I know i have other topic with same thing .Here I have example  before and after silver denarius  with lead deposits cleaned with ammonia
the result is lead is gone copper stays .
Do NOT USE THE WRONG SUBSTANCE
For COPPER  use lemon juice
For Lead only use ammonia

Ammonia is toxic use only outside and for lead deposits. Dip the coin in glass jar with ammonia just enough to cover the coin close the lid "Ammonia will evaporate if you don't close the lid "
Every 15 min check the coin rub with fingers until you like the result DO NOT OVERUSE AMMONIA IT WILL DAMAGE THE COIN "
In my case for this Vespesian the coin was in ammonia for 3-4 hours and i was checking it every 15-20 min


Step 2 is to use lemon juice to remove the copper deposits which im not going to do just because i think the coin looks great with them .
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Dk0311USMC on January 19, 2013, 04:46:16 pm
My latest project...  I have quite a bit of experience cleaning bronze coins, but this will be my first adventure trying to clean encrustations off a silver coin.  From some of the reading earlier in this thread I am thinking on using a variety of methods including distilled water, lemon juice and vinegar, as well as careful scrubbing with a nylon brush.  My greatest fear is scratching the silver so I'm thinking this is going to be a long slow project.  My uncleaned bronze coins I have got down to a science and am usually able to clean many up in short periods of time, but this will be a different animal, having to take care not to scratch the silver.

If anyone has any additional advice before I begin please share!   
Thank, Danny
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Sosius on September 23, 2013, 10:56:58 am
It's been a while since I cleaned coins, but I came across this article by accident.  It's a Reader's Digest "slideshow" with 13 tricks for cleaning silverware. Many of them made me think of the things I learned on this board. There are familiar things here, like lemon juice and aluminum foil, and some things that seem dangerous, like toothpaste, but there are also some unique methods, like using ketchup.  Now that's something that all of us Yanks should have in the fridge!  I assume it works because it's acidic, having both vinegar and fruit acids.

Who knows, some of these tricks might work on silver coins. I'd be interested in hearing your thoughts. 

http://www.rd.com/slideshows/how-to-clean-silver/

Sosius

PS: If you're an Aussie, you might want to try Vegemite instead of ketchup. It could wind up being the ultimate coin cleaning potion! Better than eating it, that's for sure.  :evil:
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: superflex on September 24, 2013, 02:56:40 am
From my experience here's what i have found works:

Water down some lemon juice, and apply to the coin using cotton ear buds.

Slowly increase the amount of lemon for stronger acidity.

Be careful with using lemon though, slowly apply water downed solutions first, watch the toning !

You could also try a two to one ammonia soak.

Start on the harder encrustations first.

As an Aussie i suggest not wasting any vegemite on your coins. Much better results on your toast for breakfast.
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Jackson G on June 24, 2015, 09:53:58 pm
I appear to have found a silver coin, but it has a thick layer of blueish encrustations on both sides and a layer of brown on one side and hard to clean mechanically. Would ammonia work for cleaning it or would i need something stronger? I did a test scratch on the edge and it appears silver, not silvered.   any ideas???
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: Lee S on July 25, 2015, 07:46:14 am
Hi Jackson...

Here is a post describing how I cleaned an encrusted silver coin... If your coin looks anything like it then the same methods will work...

https://www.forumancientcoins.com/board/index.php?topic=99174.0

 However if you post photos of your coin it will be possible to give more specific advice...

Best wishes!!

Lee.
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: *Andre* C on February 01, 2016, 01:48:51 pm
Very rarely, and only for coins of high grade AR - weak solution Trilon B. For Roman AR coins suitable gel used by dentists
For a long time he wrote the article, it is in Russian, but the illustrations are clear.

https://tinyurl.com/yx4y45p6

For coins of local dressing (Cimmerion Bosporos and Taurische Chersonesos  ) - it is better without chemicals.
But sometimes the gel helps :)
Title: Re: How to Clean Silver (not Silvered) Coins
Post by: B-Chicago on April 11, 2018, 01:34:59 pm
for the red stuff on silver coins I let them soak in distilled water for months - it tends to spread a little and often turns greenish

that's when I dip them in lemon juice for a short bath

rinse and repeat over many months

eventually it will break down

sorry I dont have any pics but this is what works bet for me and red on silver

also can try wrapping in tinfoil and boiling in water with several tablespoons of baking soda if you're in a hurry but it often doesn't get it all off