Cleaning Coins with Ammonia

Was at my LCS yesterday talking about some dirty coins. He is an extremely reputable dealer and had 4 awards for PCGS Morgan registry sets. He also helped contribute to the Red Book, so I tend to trust his advice. Anyways, he mentioned cleaning some coins with acetone first (which I was already doing at home that day) but he also mentioned soaking in a 50/50 mix of ammonia and water. Has anyone ever done that before?

 

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Yes, many times. It is generally worthwhile only on stained SILVER AU-BU sliders.

There is no abrasive content to ammonia, it is strictly a chemical reaction. It will REMOVE toning in a flash. NEVER use ammonia on copper, nickel, brass; nothing but silver. It tends to modify the natural color of gold, making it more yellow, so I don't use ammonia on gold either. That may be the natural reaction between ammonia and the 10% copper normally alloyed into gold coins.

Household ammonia (NH3 in water) is not flammable. Strictly my opinions.

 

Great advice! Thanks for the write up.

 

I personally would not ever clean a coin. jmho

 

I would be careful handling ammonia and make sure your glass container doesn't have any soap scum (that may contain bleach) as that will cause an additional chemical reaction.

 

I use neat household ammonia applied with a Qtip on filthy silver coins.
The only thing I might add is use it in a well ventilated area as ammonia fumes are colorless, highly irritating with a pungent, suffocating odor.
It is also an irritant on skin, use running water to rinse off.

 

Good advice, it produces chlorine gas which is toxic and deadly.

 

I metal detect and found some iron relics so I did some electrolysis in my house. I never heavily read the guide on how to do it. I added a bunch of table salt to the mix. I started smelling chlorine, like a swimming pool, except stronger. I left the room and looked up "chlorine electrolysis" on Google, I read this, "WARNING: Do not add table salt to the mix, it produces deadly chlorine gas" I panicked when I found out, I dumped out the solution and closed that room and opened a window.

 

Most (All?) US silver coins are alloyed with copper too.
And if it removes toning then it's the same as a silver dip; it also removes some of the metal.

And household ammonia is ammonium hydroxide (NH4OH) I believe.

 

Well...that changes everything....

 

Ammonia dissolved in water is always ammonium hydroxide. And believe me you are NOT going to be using straight ammonia unless you are working under a fume hood or have breathing apparatus.

 

Used it on many silver coins from sterling 92.5% down to 40% for over 10 years and never had a problem.
Non of my coins have turned black.
I`m going to use it later on a non numismatic Sterling silver medal that needs cleaning up.

 

"prolonged contact" is likely the key to whether it turns silver black. It's up to you to determine how long that would be!

 

Everything I see says it turns black silver bright and not the other way around. It does this by dissolving the silver chloride. And I cannot believe there would possible be enough "silver compounds" produced for there to be any problems and the several webs I found (mostly to clean silverware) seem to concur with this.

 

I rarely disagree with you Conder, but you're wrong.

Ammonia + water = ammonium hydroxide formed

For the record, straight ammonia is a gas.

 

I missed it. What are you disagreeing with?

 

Listen to BadThad, NH3 is a gas. I once had the opportunity to run a reaction using liquid ammonia (NH3). You condense it to a liquid using dry ice. Scary stuff. What most people refer to as ammonia is a solution in water. Commercial ammonia (or ammonium hydroxide, which is what NH3 + H2O becomes in solution) is about 30% by weight ammonia.

Exposure of silver to household ammonia followed by extensive rinsing would probably cause no damage.

 

Absolutely. I used to work with and in it. It is used to preserve natural rubber latex. About 5:00 everyday it got very ripe handling 100,000+ gallons per day. But what I read, Conder said the same thing although he did not use the word "gas".