Acetone Made Silver Ike worse

just a difference in opinion, @Insider

we're entitled to those

 

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mikenoodle, posted: "Just a difference in opinion, we're entitled to those."

Yes, you are. As I said Mike, I'm not picking on you or any others posting in this thread. However, in this case, the difference between your opinion and my actual experience professionally conserving "X" number of rare and valuable coins is that I had just a tiny-weenie-bit of training by an internationally known professional conservator, a nationally known and published chemist consultant, and some pretty amazing professional dealers who are coin doctors.

Don't forget to neutralize the acid.

PS You all will be glad to know that I have found another coin forum I really like.

 

You're not gonna like me and leave me, are you?

 

I suggested the avoiding the baking soda solution to simplify the process. For people without experience in a Chem lab setting, the less chemicals to play with, the less chance of making mistakes. Thorough rinsing in distilled water should dilute and wash away any remaining thiourea and sulfuric acid, particularly in the concentrations found in commercially available dips. (De-ionized water would probably be better, but most people don’t have access to it)


If you’re doing precision dips for very short periods of time or with higher concentrations of active chemicals, then a baking soda (sodium bicarbonate) solution should neutralize the H2SO4 a little faster than ordinary rinsing. I don’t know if it has any effect on the thiourea reaction with the silver (where are those chemists when you need them @Kentucky), but the baking soda solution probably just rinses it off.


If you're new to playing with chemistry, you probably don’t need to use baking soda AS LONG AS YOU RINSE AND DRY THOROUGHLY. Keep it simple IMO. If you have the chem lab or coin conservation experience (Dr. White for example), then you probably know when to use a neutralizing solution.

 

I am going to post pictures of the coin I dipped before and after in a day or two. I was told that if any spots showing up from the acid would have revealed themselves by now. I have several more silver Ikes to dip and experiment on! One question I had was the patting down with cloth after distilled water rinse. How do you do this correctly? I didn't use a specialty cloth, just a brand new one. @Insider @Kentucky @mikenoodle

 

I have used micro-fiber and soft terry cloth. Both work as long as you don't rub the surface

 

I just rinse with acetone, which takes care of remaining surface water and evaporates without physical "drying." From the dip, under running hot water, plop into an acetone soak/rinse. Dunno why people insist on additional minerals or chemicals; if you blast the acid off under a stream of water it doesn't hang around long enough to need neutralizing.

 

I agree that additional steps are overkill, Dave.

I also agree that rinsing in acetone will make the coin dry completely on its own, and typically spot-free.

 

Well, I did find this from Coin World a few years back:

http://www.coinworld.com/news/precious-metals/2013/12/silver-dips-unrecommended.all.html

I get my back up a bit when I see someone claim "research has shown" without an explicit reference to the research. Maybe they're referring to the paper cited earlier in the article, but I can't be sure, and I can't get to that paper.

But the claims they're making ("the bond... is so strong that it is impossible to break") are nonsensical on their face. If the bond is so strong, how can the thiourea continue to react and cause further damage? Either it's bonded and stuck there, or it's loose and ready to react further.

Sure wish someone with an electron microscope would examine some half-dipped coins. Hello, @Electron John ?

 

Is there a resource that we don't have on this forum???

 

There's always room for more resources! Still waiting for time on a good X-ray free-electron laser to date "dateless" Buffalos without etching them, and to see if anything can be recovered from dateless SLQs.

 

more resources is a great thing. the number and variance of those available here blows my mind at times.

 

jeffB, posted: "There's always room for more resources! Still waiting for time on a good X-ray free-electron laser to date "dateless" Buffalos without etching them, and to see if anything can be recovered from dateless SLQs."

It may work as the designs of a coin continue into their interior.

Now for some humor before posting more: I sent out three dateless AG buffalo nickels to a young fellow and he returned them to me with a note that he had the "holes" for those three dates already filled!

Next. I should have PM'ed certain posters about neutralizing a coin. The comments in this thread "rubbed me the wrong way" due to something going on at work and I revealed too much as a way of "smacking down" what I took as some dangerous misinformation.

Oldhoopster, posted: "I suggested the avoiding the baking soda solution to simplify the process. For people without experience in a Chem lab setting, the less chemicals to play with, the less chance of making mistakes. Thorough rinsing in distilled water should dilute and wash away any remaining thiourea and sulfuric acid, particularly in the concentrations found in commercially available dips. (De-ionized water would probably be better, but most people don’t have access to it).
If you’re doing precision dips for very short periods of time or with higher concentrations of active chemicals, then a baking soda (sodium bicarbonate) solution should neutralize the H2SO4 a little faster than ordinary rinsing. I don’t know if it has any effect on the thiourea reaction with the silver (where are those chemists when you need them @Kentucky), but the baking soda solution probably just rinses it off."
If you're new to playing with chemistry, you probably don’t need to use baking soda AS LONG AS YOU RINSE AND DRY THOROUGHLY. Keep it simple IMO. If you have the chem lab or coin conservation experience (Dr. White for example), then you probably know when to use a neutralizing solution."

Baking soda in solution is virtually harmless. A running water rinse does not neutralize the chemicals thoroughly. That's why so many silver coins are seen with flowing brown stains indicating improper rinsing.

Bman33, posted: "I was told that if any spots showing up from the acid would have revealed themselves by now."

This is absolutely FALSE in most cases. It all depends on the environment as to when the stains will appear.

Bman33 continued: "I have several more silver Ikes to dip and experiment on! One question I had was the patting down with cloth after distilled water rinse. How do you do this correctly? I didn't use a specialty cloth, just a brand new one."

Look, most coin dealers don't have the time, expertise, or even bother to dip coins properly. I worked for a dealer who dipped a dollar, dried it with a towel and sold it an hour later. No big deal. The same dealer dumped original BU silver quarters in a bucket of ammonia, ran water on them until the smell was gone and dumped them on to towels and dried the batch with more towels. What I'm trying to say is that all the KISS methods are just that - improper and cringe worthy. No rags touch coins when you are a professional.

mikenoodle, posted: "I have used micro-fiber and soft terry cloth. Both work as long as you don't rub the surface."

Sure it works...see above. Only thing, blotting coins leaves a residue. If you dry your coins like this it is best to finish off with an acetone dip!

mikenoodle, posted: "I agree that additional steps are overkill, Dave.
I also agree that rinsing in acetone will make the coin dry completely on its own, and typically spot-free."

Keyword: "typically"

There are several ways to do things. Some work better than others. While some methods to dip a coin may be considered unnecessary and "overkill," others may be inadequate or not suitable for professional conservation. Usually, over time or even by just looking at a coin when a collector has dipped it the truth of my statement will be obvious.

Furthermore, I cannot believe not one poster on this thread has ever seen acetone dry as a haze or spot on a coin after it was removed from a "finishing" dip. I could post an image but I'll let you see for yourselves.

 

keyword: usually

Nothing is always and never. Sometimes things work, sometimes they don't.

 

@Insider ...what other coin forum? To address a few points above, a solution of baking soda (sodium hydrogencarbonate) will neutralize any residual acid hiding in the nooks and crannies of a coin, but these same nooks and crannies should be accessible to the rinse water, so the baking soda rinse is "gilding the lily" but should not be harmful as long as the coin is rinsed with water and distilled water in the end. I'm not really fond of a final acetone rinse since this would tend to cause any dissolved inorganic substances to drop out and perhaps leave a haze on the coin as @Insider mentioned.

As far as drying, most any clean cloth should work as long as you don't rub, especially uncirculated and proof coins. I usually lay the cleaned/wet coin on a clean towel, fold another section over it and press with my hand. Uncover the coin and it should be done.

Finally for the reference given, some thoughts...museum conservators are the ones who polished coins in museum displays until they were little more than metal disks, the nonsense about a thiourea bond to a silver surface being impossible to break is pure snake oil, the author promised a future article featuring safer alternative methods to clean silver, but a quick search by me didn't reveal it. One last point, what were these 98% Mexican silver coins they npracticed their cleaning on?

 

Thanks for the confirmation that I'm not nuts.

 

Collector's Universe is jumping. Lots of the "Big Guns" over there. I've gotten two that everyone knows to sign up with us over here. Several others say they don't have time to belong to more than one site. Their loss!

Thanks Kentucky! Ultrasonic gets places we can't even begin to see. And yes, the many former curators' at the Smithsonian ruined much of our National Collection before they knew better.