Author Topic: Possible WSOD explanation?  (Read 15463 times)

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Offline Panda Halves

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Possible WSOD explanation?
« on: August 06, 2011, 08:13:34 PM »
Are water contaminants the source of WSOD(White Spots of DEATH!) instead of packaging?

“The most common pollutants in Shanghai drinking water are high levels of chlorine, bacteria, and lead and toxic heavy metals.  Shanghai’s water authorities have publicly acknowledged that tap water potability is compromised largely by secondary contamination from old piping.  The heavy use of chlorine is necessary for disinfection, but is also unhealthy and can create carcinogenic byproducts.”

Source: http://www.purelivingchina.com/learning-center/water-quality/

If the water in China has this many pollutants then is it possible that these pollutants are getting deposited on the surface of coins when either the blank planchets are quenched or washed?  Perhaps the reason latter date coins seem to be more and more susceptible to WSOD is that the levels of chlorine, heavy metals, and other contaminants have risen in the water supply of the cities where the coins are being minted. This could explain why, although the packaging seems to be improved, the WSOD phenomenon seems to be actually getting worse. Many 2011 Aviation Industry silver pandas I’ve seen are plagued with spots straight from the mint. Perhaps the coins are washed and dried but the contaminants in the water supply are being deposited on the coin then the coin along with the contaminants is “sealed.” It wouldn’t matter what this sealed plastic holder is made of if the surface of the coin is contaminated. As population levels have risen in industrial areas more contaminants have entered the water supply, along with more unwanted contaminants, additives such as chlorine are added to the water in attempt to purify it for drinking. Both additives and contaminants are not good for coins. This is of course… all speculation but is it at least plausible? Thoughts?

Offline badon

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Re: Possible WSOD explanation?
« Reply #1 on: August 06, 2011, 08:35:51 PM »
This is very possible. My analysis of the issue determined that the white spots were caused by chlorine. I've made a few detailed posts on LBC and CCF describing how the reaction works, how to prevent it, and possibly how to reverse it.

I don't have them handy in front of me though, so you'll have to do a search to find them.

Offline adamc4

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Re: Possible WSOD explanation?
« Reply #2 on: August 06, 2011, 08:49:58 PM »
My question is: even after NCS + NGC can white spots 1) appear 2) get worse and grow or 3) be "frozen" in their current state?

Offline Panda Halves

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Re: Possible WSOD explanation?
« Reply #3 on: August 06, 2011, 08:57:25 PM »
Badon, do you think the chlorine could possibly come from the over-chlorinated water supply vice outgassing?

Offline badon

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Re: Possible WSOD explanation?
« Reply #4 on: August 06, 2011, 09:11:05 PM »
My question is: even after NCS + NGC can white spots 1) appear 2) get worse and grow or 3) be "frozen" in their current state?

1. Yes, especially if the reaction has already started before the conservation process, which can't always been seen visually.

2. Get worse, yes. Grow, no. Although it is theoretically possible for a properly conserved coin to get worse over time, I haven't seen it yet. The conserved coins I have seen with white spots seem to be much more stable over time, since most of the chlorine got rinsed away in the conservation process. The only way to make it worse in theory is probably repeated cyclical exposure to humidity, UV light (sunlight), or both.

3. This is what SEEMS to be the case so far for white spots that have been conserved. The conservation process seems to stop the spot reaction process by removing the free chlorine. Once that's gone, all that's left is the chlorine that's already reacted with the silver to produce AgCl molecules. That just seems to sit there and do nothing, although I do think it's possible for it to continue damaging the coin. I might try to do some tests someday to see what happens. I have owned a coin that was conserved after spots formed, and I noticed no changes after 5 years. Conservation seems to have greatly improved the coin's appearance, and stopped the reaction.

Badon, do you think the chlorine could possibly come from the over-chlorinated water supply vice outgassing?

White spots never come from outgassing, or anything else related to the packaging. White spots come from a very simple chlorine reaction, and they always have the bulbous shape of water stains. I think it is very likely that it comes from some kind of water - maybe the drinking water supply, or maybe a diluted hydrochloric acid solution (to clean the planchets). Or both!

Offline poconopenn

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Re: Possible WSOD explanation?
« Reply #5 on: August 06, 2011, 10:32:18 PM »
WSOD also show up in eagles and maples. This is not just the problem of silver panda. It has to be related to the production of  planchets, an unknown impurity in the planchets which may be oxidized to form a white spot. Silver is known to be the by product of zinc, copper and gold mining. If I have to take a guess, the zinc may be the one, since zinc oxide is a white color powder.

Offline badon

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Re: Possible WSOD explanation?
« Reply #6 on: August 07, 2011, 02:15:56 AM »
ZnO is too white. WSoD look a little bit darker than the bright white ZnO, which is the main ingredient in powerful sunblock lotions. Also, the "stain" patterns do not match what impurities normally look like.

http://en.wikipedia.org/wiki/Zinc_oxide
http://en.wikipedia.org/wiki/Silver_chloride

I  have seen impurities that look like they might be a bit of zinc in the silver, so it is an interesting possibility in some cases. In the case of WSoD, the reaction rate is too fast. Plus, zinc isn't very prone to oxidation, that's why it's used as the coating for galvanized steel. It oxidizes less readily than iron does.

Within a coin's original seal, I would expect zinc to remain pristine for a very long time. Maybe there would be a gap in the toning on a silver coin, where the zinc didn't oxidize, but the silver did.

It would be interesting to test the white spot to find out for sure what it is.

Offline Panda Halves

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Re: Possible WSOD explanation?
« Reply #7 on: August 07, 2011, 08:04:37 AM »
Maybe someone with connections should find the most spot covered common silver coin and send it to a university chemistry laboratory for analysis.
Analyzing Chinese silver and gold coin surface contaminants make a good research paper for some student.
If the impurities are from a water source then it would make sense that different mints would be more likely to develop the spots than others, especially since Shanghai seems to have such hard/chlorinated water. Scientificall proving what they are would make the case for conservation even stronger.

Offline badon

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Re: Possible WSOD explanation?
« Reply #8 on: August 07, 2011, 11:33:33 AM »
I've found evidence that they're from a liquid or water source. They ALWAYS have a smooth border with a bulbous shape. Water always has some dust, debris, or dissolved minerals in it, just like hard water. As the drop of water evaporates, the drop shrinks, but it does not leave behind the dust etc that is in it until it shrinks to a speck and evaporates completely.

All round WSoD's have a speck of dirt right at their center, just like I described above. Knowing that they come from water rules out a lot of possibilities, including the ZnO hypothesis. The most likely possibility is AgCl. I cannot think of any other thing it could be.

Still, it would be good to confirm it.

Offline poconopenn

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Re: Possible WSOD explanation?
« Reply #9 on: August 07, 2011, 02:04:39 PM »
Please note that de-ionized water is used in cleaning the dies, planchets and coins in Mints. This is a standard procedure used by all Mints. The hardness and chlorine gas in the water are not the issue.

Offline badon

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Re: Possible WSOD explanation?
« Reply #10 on: August 07, 2011, 02:13:08 PM »
Possibly there was a problem in the quality of the rinse. The planchets were probably pickled in an acid bath to clean them, and then they were rinsed. If the rinsing was incomplete, diluted acid would dry on the surface of the planchet. This explains why exposure to humidity causes struck coins to develop spots decades later.

Offline fwang2450

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Re: Possible WSOD explanation?
« Reply #11 on: November 29, 2012, 05:51:30 PM »
It turned out that Shanghai Mint did their own research long time ago, in 2002. Attached are two articles from Shanghai Mint (in Chinese, one of them published in a journal) discussing white spots on silver coins, method to remove them and how to prevent them. Mr. Feng (RAREMEDAL) referred to the articles in his post on coin oxidation: http://bbs.jibi.net/dispbbs.asp?boardid=176&Id=206388&page=4

The article in the PDF format confirms that the white stuff is caused by chlorine, and that normal acid bath cannot remove it. They suggested using chromium trioxide to form a film, then removing the film with ammonia and using sulfuric acid for polishing (?) as a way to get rid of the white spots. I guess this can only be done by professionals, like those at NCS.

Interestingly, the article does not mention where the chlorine came from, but water was mentioned as one of the possible causes.

The article in the Word format mentions iron in small white spots (about 1mm). In the center there is a little black dot, which turns out to be iron. It interacts with chlorine to form little white spots.

Offline poconopenn

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Re: Possible WSOD explanation?
« Reply #12 on: December 02, 2012, 01:53:31 AM »
Fwang2450, thanks for posting this very interesting article.

The authors observed a very small dark particle under the white film in their study. This is a very significant finding. Furthermore, they suggest the dark particle is related to iron as impurity introduced during the minting process.

The results of instrumentation of white spots reveal unusual amount of chlorine, oxygen and sodium, while the dark spots has a detectable amount of iron. The authors did not provide a clear interpretation of the chemical mechanism of the formation of the white film but simply suggested the silver surface containing iron might be corroded by chlorine and sodium which caused the discoloration of the surrounded area.

Here are some facts which authors of this article may not know.

Very few double sealed mint packaged coins develop white spot. Practically, all coins made with silver purity in 90-92.5% do not develop white spots. NGC and PCGS encased coins can develop white spot inside the holder. The white spots also show up in eagle and maple, but not in any silver coin made by Australia Mint.

IMO, the iron is not introduced during the minting process, but from the impurity of the silver raw material. I also believe the sources of chlorine and sodium is from human contact such as sweat or mist from breath. Both sweat and breath contain sodium chloride (salt) which can be acted as corrosive agent and react to iron to form ferrous chloride which is white in powder form.

Offline dynamike51

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Re: Possible WSOD explanation?
« Reply #13 on: December 02, 2012, 02:19:47 AM »

Very few double sealed mint packaged coins develop white spot. Practically, all coins made with silver purity in 90-92.5% do not develop white spots. NGC and PCGS encased coins can develop white spot inside the holder. The white spots also show up in eagle and maple, but not in any silver coin made by Australia Mint.


poconopenn:

According to your post, is it correct to assume whatever is causing the white spots (be it the human breath or sweat) occurs during the NCS/NGC/PCGS process ?
« Last Edit: December 02, 2012, 02:28:52 AM by dynamike51 »

Offline fwang2450

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Re: Possible WSOD explanation?
« Reply #14 on: December 02, 2012, 02:32:15 PM »
Fwang2450, thanks for posting this very interesting article.

The authors observed a very small dark particle under the white film in their study. This is a very significant finding. Furthermore, they suggest the dark particle is related to iron as impurity introduced during the minting process.

The results of instrumentation of white spots reveal unusual amount of chlorine, oxygen and sodium, while the dark spots has a detectable amount of iron. The authors did not provide a clear interpretation of the chemical mechanism of the formation of the white film but simply suggested the silver surface containing iron might be corroded by chlorine and sodium which caused the discoloration of the surrounded area.

Here are some facts which authors of this article may not know.

Very few double sealed mint packaged coins develop white spot. Practically, all coins made with silver purity in 90-92.5% do not develop white spots. NGC and PCGS encased coins can develop white spot inside the holder. The white spots also show up in eagle and maple, but not in any silver coin made by Australia Mint.

IMO, the iron is not introduced during the minting process, but from the impurity of the silver raw material. I also believe the sources of chlorine and sodium is from human contact such as sweat or mist from breath. Both sweat and breath contain sodium chloride (salt) which can be acted as corrosive agent and react to iron to form ferrous chloride which is white in powder form.

poconopenn:

There are two articles. The Word article talks about 1mm white spots, which has some iron particles in the center. I don't believe this is the kind of white spots we are talking about. The white spots that catch most attention are much bigger.

The article does not specifically say the iron particle is introduced in the minting process, which is 加工 in their terminology. Instead, the authors claim that the iron is added in the production of the silver base material. That is why the number one preventive measure proposed is "enhance the quality of the base material."

In the PDF file, there is no mention of iron as the cause of the white spots, but the authors do provide an analysis of the chemical process which lead to the white spots.

About the environment of white spot formation, I have read that a large number of the new Wutai Mountain silver coins develop white spots when double sealed. Also, I have a 15g Compass silver coin with two white spots. Its fineness is 90%. Of course these are just personal observations. More input is needed to validate the exact conditions for the development of white spots.

Now that Shanghai Mint knows the cause of white spots (chlorine), and the proposed solutions from these authors, and yet white spots still appear in force on their coins (Wutai was minted by Shanghai Mint and Shenzhen Mint), the only explanation is the cost or process. Maybe they are just using untreated tap water which is rich in chlorine instead of deionized water. Or they use hydrochloric acid to clean the planchets without complete rincing. (Mr. Feng cited pugent gas in the mintng process.) It is really puzzling that they pinned down the cause 10 years ago and are still producing coins with white spots, which directly impact their sales.

I have not personally seen white spots on American or Canadian silver coins. But from what I read, the white fog on silver Maples is different in shape from the WSOD. Also, the Canadian Mint acknowledged that the white fog was caused by boric acid remnant, but they have done nothing about it as silver Maples are just bullion coins. There are videos on Youtube on how to remove the white fog on silver Maples.

Offline cabaretvolt

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Re: Possible WSOD explanation?
« Reply #15 on: December 02, 2012, 02:59:45 PM »
how do these white spots ordinarily affect grading and value
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Offline fwang2450

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Re: Possible WSOD explanation?
« Reply #16 on: December 02, 2012, 08:54:20 PM »
how do these white spots ordinarily affect grading and value
Unlike toning, white spots negatively affect both the grading and the value of the coin.

Offline poconopenn

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Re: Possible WSOD explanation?
« Reply #17 on: December 03, 2012, 12:44:42 AM »
how do these white spots ordinarily affect grading and value

http://www.pcgs.com/eyeappeal.html

Offline poconopenn

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Re: Possible WSOD explanation?
« Reply #18 on: December 03, 2012, 01:18:08 AM »
Fwang450.

The authors had considered the existence of unusual amount of C in the tested white spots as an environment element and not important in their interpreting of the formation of white spots. IMO, this is incorrect. The C element can be originated from organic substance in sweat and saliva. The authors also did not mention the detection of large amount of potassium in one of two samples tested. Again, potassium, similar to sodium and chloride is a major ingredient in sweat and salvia. IMO, the data generated from this study is clearly suggesting that the formation of white spots is from residue of human fluid such as sweat and saliva left on the coin surface. China Mint in its official document has indicated that the staffs of Quality Control conduct manual inspection about 30% of the coins produced. This gives a lot of chance to contaminate the coin surface by human fluid.

The cost of production of de-ionized water is very limited. In general, the cost is about $0.01/gal for 50 ton/day capacity. It is my understanding that China Mint always uses de-ionized water in its minting processs.


IMO, there are many different forms of white spots (milk spots). The one mentioned in the Word article is caused by iron “in” the surface. Other white spots mentioned in PDF file article are “on” the surface. The one “on” the surface with no iron involved can be readily removed if it is done properly and earlier.

The earlier Maples (pre-2000) were sealed in plastic and did not see white spots as many as the recent minted Maples, which were no longer sealed. The proof Eagles are also sealed in hard plastic holders, and they do not develop white spots in their original package for many years, in contrast to BU silver Eagles. All these observations suggest the extra handling by bare hand and the mist of breath during close examination of coin with a magnifier in the grading process may contaminate the coin surface further and cause more “white spots” problem inside the holder. The grading companies have expanded their business so much that new hired graders may not have a proper training to minimize the contamination during the grading process.




Offline Hippanda

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Re: Possible WSOD explanation?
« Reply #19 on: December 03, 2012, 01:19:37 AM »
Excellent analysis.

Thank you
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Offline dynamike51

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Re: Possible WSOD explanation?
« Reply #20 on: December 03, 2012, 01:37:49 AM »

All these observations suggest the extra handling by bare hand and the mist of breath during close examination of coin with a magnifier in the grading process may contaminate the coin surface further and cause more “white spots” problem inside the holder. The grading companies have expanded their business so much that new hired graders may not have a proper training to minimize the contamination during the grading process.


poconopenn,

Kudos to your great analysis. Thank you for answering my question. If the contamination is introduced during the minting and grading process, "quality control" or even some type of "clean room" environment definitely should be in order for all these outfits.

Offline dynamike51

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Re: Possible WSOD explanation?
« Reply #21 on: December 03, 2012, 12:38:40 PM »
RCM is well known for its problem with having WSODs on silver coins; now China Mint seems to have similar predicament. How about Perth Mint? Does anyone know of any particular issues with Australian silver coins?

Offline heyimderrick

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Re: Possible WSOD explanation?
« Reply #22 on: December 03, 2012, 12:53:31 PM »
I've sent back many NGC-graded pandas under their guarantee after they developed the white spots and stains after being encapsulated. I've had this problem most commonly with post-2009 issues, although I've seen it on the majority of years like most of you. I agree that it has gotten far worse in recent years.

After much frustration, I called NGC and spoke with Craig Fiumara directly about what was causing the white spotting and staining on these coins, and why NCS could not take care of them (I actually thought that it could have been improper drying by NCS/NGC). He told me that it is caused from contaminants on the planchets that end up being pressed into the metal during the minting process. He didn't specify what the contaminants were, just that it's from what they use to clean the planchets. Since it is not a substance simply residing on the surface of the coin, there's nothing NCS can do to remove it.

Offline dynamike51

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Re: Possible WSOD explanation?
« Reply #23 on: December 03, 2012, 01:07:03 PM »
I've sent back many NGC-graded pandas under their guarantee after they developed the white spots and stains after being encapsulated. I've had this problem most commonly with post-2009 issues, although I've seen it on the majority of years like most of you. I agree that it has gotten far worse in recent years.

After much frustration, I called NGC and spoke with Craig Fiumara directly about what was causing the white spotting and staining on these coins, and why NCS could not take care of them (I actually thought that it could have been improper drying by NCS/NGC). He told me that it is caused from contaminants on the planchets that end up being pressed into the metal during the minting process. He didn't specify what the contaminants were, just that it's from what they use to clean the planchets. Since it is not a substance simply residing on the surface of the coin, there's nothing NCS can do to remove it.

heyimderrick,

Have you noticed this particular problem with Australian silver coins?

Offline heyimderrick

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Re: Possible WSOD explanation?
« Reply #24 on: December 03, 2012, 01:26:49 PM »
heyimderrick,

Have you noticed this particular problem with Australian silver coins?

I have not. I was a collector of the Koalas (sold), I have a full run of the Kookaburras and both Lunar Series, and I have not seen any spotting or staining at all on the Perth Mint products. I've flipped a lot of Kooks and Lunars also and never had any issues with spotting/staining of any kind.

I have seen some minor spots on some ASEs (rarely) with the frosted finish that looks similar to some of the small spots we see on Pandas. The staining on Maples and Wildlife Series I have seen does look different as well.

On Pandas, In my experience, I generally see very faint, small white spots. Or, large splotchy stains with almost a yellowish tint, generally on the frosted areas towards and along the rim. Coins plagued by both kinds of marks were covered under NGC's guarantee when I sent them in for appearance review.

I've personally sent in a handful of Pandas with the small, faint white spots to NCS, and none we ever removed entirely and usually only slightly improved. While I owned the coins, the spots didn't get worse, but I have since sold off my entire silver collection of Pandas. While I still dabble in flipping silver Pandas to help fuel my addiction, I am sticking to gold Pandas for my personal collection.

Offline NBM

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Re: Possible WSOD explanation?
« Reply #25 on: December 03, 2012, 01:35:34 PM »
There were reports in the last year of some of Perth's silver coins having WSOD. I can not find these posts currently.

Offline dynamike51

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Re: Possible WSOD explanation?
« Reply #26 on: December 03, 2012, 01:36:00 PM »

While I still dabble in flipping silver Pandas to help fuel my addiction


LOL ... you and I both !!   :lol:  Maybe we need to check in rehab center somewhere ...

Offline heyimderrick

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Re: Possible WSOD explanation?
« Reply #27 on: December 03, 2012, 01:47:25 PM »
There were reports in the last year of some of Perth's silver coins having WSOD. I can not find these posts currently.

I'm fairly active on SilverStackers (an Australia-based forum); I've heard complaints about the quality control slipping (scratched coins, capsules), but can't say I have seen white spots myself. Although it is possible I missed it. If PM does have an issue with them, it must be under far better control than with China or Canada.


EDIT: Just did a search and there have been a few claims of small spots showing up on some 2011/2012 Koalas.  :thumbdown:

To me, it seems the issue start getting more severe as the mints try to increase capacity. Less time available to do thorough cleaning/drying of the planchets maybe.
« Last Edit: December 03, 2012, 02:02:00 PM by heyimderrick »

Offline heyimderrick

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Re: Possible WSOD explanation?
« Reply #28 on: December 03, 2012, 01:47:57 PM »
LOL ... you and I both !!   :lol:  Maybe we need to check in rehab center somewhere ...

I get a nice reality check whenever I get stuck with a coin I overpaid for, lol. =)

Offline fwang2450

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Re: Possible WSOD explanation?
« Reply #29 on: December 03, 2012, 02:46:49 PM »
I've sent back many NGC-graded pandas under their guarantee after they developed the white spots and stains after being encapsulated. I've had this problem most commonly with post-2009 issues, although I've seen it on the majority of years like most of you. I agree that it has gotten far worse in recent years.

After much frustration, I called NGC and spoke with Craig Fiumara directly about what was causing the white spotting and staining on these coins, and why NCS could not take care of them (I actually thought that it could have been improper drying by NCS/NGC). He told me that it is caused from contaminants on the planchets that end up being pressed into the metal during the minting process. He didn't specify what the contaminants were, just that it's from what they use to clean the planchets. Since it is not a substance simply residing on the surface of the coin, there's nothing NCS can do to remove it.
Thanks for passing this information.

Offline poconopenn

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Re: Possible WSOD explanation?
« Reply #30 on: December 03, 2012, 03:14:58 PM »
I've sent back many NGC-graded pandas under their guarantee after they developed the white spots and stains after being encapsulated. I've had this problem most commonly with post-2009 issues, although I've seen it on the majority of years like most of you. I agree that it has gotten far worse in recent years.

After much frustration, I called NGC and spoke with Craig Fiumara directly about what was causing the white spotting and staining on these coins, and why NCS could not take care of them (I actually thought that it could have been improper drying by NCS/NGC). He told me that it is caused from contaminants on the planchets that end up being pressed into the metal during the minting process. He didn't specify what the contaminants were, just that it's from what they use to clean the planchets. Since it is not a substance simply residing on the surface of the coin, there's nothing NCS can do to remove it.

There are definitely many different forms of white spots. The Chinese articles have identified two types and large white spots shown on Maples caused by boric acid, as confirmed by Canadian Mint, is another type. IMO, white spots "on" the surface can be removed if it is done earlier. However, if white spots are related to the impurity of the silver raw material or fine metal dusts left on the die surface during the sand blasting process, the removal of this type spots will be very difficult.

Offline Honus

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Re: Possible WSOD explanation?
« Reply #31 on: December 03, 2012, 03:21:12 PM »
RCM is well known for its problem with having WSODs on silver coins; now China Mint seems to have similar predicament. How about Perth Mint? Does anyone know of any particular issues with Australian silver coins?

I've personally seen them on NGC-graded Kooks and the 2oz Perth Tiger silvers. 
Eric Liquori
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Offline silverstar1

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Re: Possible WSOD explanation?
« Reply #32 on: December 13, 2012, 09:22:57 PM »
I just noticed this thread .. The white spots have been something of interest to me for quite a while. This is a great article and the first I have seen with a scientific explanation, and that is really the only way to get to the bottom of what is causing these. Through my observations I do also believe there is at least 2 maybe 3 or more different causes of these. On the Chinese coins I have noticed 2, one which is as described above as a very small darker speck (far less than 1mm from what I have seen) with the white spots surrounding that, another is more just round white and even blotchy white spots. With the Canadian coins some are round spots and some also like the Chinese coins are more white blotches . On the Australian Perth mint spots yes some do have them they tend to have more of a bluish hue and I have only observed round ones not the large blotchy types. I really think someone ,a scientist of sorts with the equipment , knowledge and desire would have to do some extensive testing on different types of coins to really find the truth of what is causing these . It is also a thought I have had that some may be caused or enhanced by some reaction of a pollutant in the environment that causes a secondary reaction. I have personally never seen these spots appear later on a coin such as after grading but I have heard others that believe this is the case . Some of that could just be observing them in different light and angles and the spots were always there but they are just now seeing them in a different light or angle. I would have to disagree that there are not many MCC in OMP with spots I have definitely seen many and have seen them from the Australian Perth mint. I think there could be several variables here hopefully we will get closer to some factual explanations.

Offline bonke

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Re: Possible WSOD explanation?
« Reply #33 on: November 02, 2013, 05:44:22 PM »
Thank you for the link.  I read the various explanations with great interest.

Poconopenn - As one of the active participants in the prior discussions, maybe, you will help us understand the present problem.  Recently, Shanghai Mint struck these 1oz and 2oz silver medals.  Possibly, many of the 1oz medals and all of the 2oz medals are showing a white stain on the edges and a white mist on the face of the medals.  Based on these problems, the NGC grades are surprisingly low.  Peter Anthony sees this stain with his medal or medals in the double plastic.  Is this being caused by the inadequate rinse of the acid, the chlorine in the rinse, the saliva of the Mint workers, etc.?  Did the coin forum members (in the prior discussions) actually arrive at a conclusion as to the cause?  Would this apply to these medals when the problem is developing so quickly and within the double plastic?

Mark Bonke

Offline fwang2450

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Re: Possible WSOD explanation?
« Reply #34 on: November 02, 2013, 06:48:51 PM »
An old topic revived. I actually uploaded a 2011 article by two engineers from Shenyang Mint in another thread, on the white spots on silver coins. These white spots are AgCl, the Cl part being from "cleaning agents in the production process", most likely the acid used to polish blanks after annealing. If rinsing is not complete, the acid stays on the coins and gets pressed into the coins. When the coins leave the mint, white spots will develop once the acid gets in touch with moisture in the air.

Offline poconopenn

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Re: Possible WSOD explanation?
« Reply #35 on: November 02, 2013, 11:33:28 PM »
An old topic revived. I actually uploaded a 2011 article by two engineers from Shenyang Mint in another thread, on the white spots on silver coins.

Please post the link. Thanks.

Offline poconopenn

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Re: Possible WSOD explanation?
« Reply #36 on: November 03, 2013, 12:00:24 AM »
Thank you for the link.  I read the various explanations with great interest.

Poconopenn - As one of the active participants in the prior discussions, maybe, you will help us understand the present problem.  Recently, Shanghai Mint struck these 1oz and 2oz silver medals.  Possibly, many of the 1oz medals and all of the 2oz medals are showing a white stain on the edges and a white mist on the face of the medals.  Based on these problems, the NGC grades are surprisingly low.  Peter Anthony sees this stain with his medal or medals in the double plastic.  Is this being caused by the inadequate rinse of the acid, the chlorine in the rinse, the saliva of the Mint workers, etc.?  Did the coin forum members (in the prior discussions) actually arrive at a conclusion as to the cause?  Would this apply to these medals when the problem is developing so quickly and within the double plastic?

Mark Bonke

It is very difficuty to see white spots on a highly frosty surface. Usually, the white spots on mirror surface will affect the grade. The pictures posted by silverybay in other thread does show some "black spots" in forsty area which may affect the grade.

Offline SANDAC

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Re: Possible WSOD explanation?
« Reply #37 on: November 03, 2013, 12:37:29 AM »
Please post the link. Thanks.
I believe this is the link fwang2450 is referring to:
http://china-mint.info/forum/index.php?topic=7823.msg45622#msg45622

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Re: Possible WSOD explanation?
« Reply #38 on: November 03, 2013, 08:32:12 PM »
I believe this is the link fwang2450 is referring to:
http://china-mint.info/forum/index.php?topic=7823.msg45622#msg45622


Thanks for posting the link. The article posted by raremedal was incompleted. The completed article can be found in the following link. The website will not allow to download the article.

http://www.docin.com/p-335727916.html (银纪念币表面滋生白斑机理研究, Kang Jin-zhe and Yu Hong, Shenyang Mint Co, Ltd., Corrosion Science and Protection Technology, Vol. 23, No 2, March 2011, Page 197-189)

Summary and comments of the article.

Summary:

1.   The article has further provided the scientific evidences that the formation of white spots can be relatively easy. The white spots can be formed as short as few days after the production of the coin, usually in several months.

2.   The composition of white spots is silver chloride and high humidity is required to promote the formation of silver chloride. The source of chloride, suggested by authors, is from environment pollutants.

3.   The change of minting process of forming mirror surface has caused more and quicker white spots formation. The old method in produce mirror surface was mechanical polish. The current method is via a chemical treatment. Apparently, according to the authors, the chemical treatment produces a rougher surface than mechanical polish. It is known that the moisture can adhere to a rougher surface better than a smooth surface, therefore, the reaction of forming silver chloride film on the silver surface is being accelerated.

4.   The formation of silver chloride film on the silver surface retards the formation of silver sulfide (the usual rainbow toning on silver coin caused by sulfur in the air after aging). The white spots will stay as white and size enlarged with time in a high humanity environment.

Comments:

1.   The article is in consistence with the observations that the earlier MCC do not show white spots as often as MCC produced in the past few years.

2.   IMO, the major source of chloride is from human contact. This article, similar to previous articles (two articles mention by fwang2450 in reply 11 of this thread), has detected significant amount of sodium, carbon and sulfur, the basic element of human fluid, in the white spots. The observation of most white spots developed near the rim and edge  suggests the introduction of sweat (sodium chloride, salt and moisture) during the hand holding inspection of coin by staffs of Mint and grading company.

Offline fwang2450

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Re: Possible WSOD explanation?
« Reply #39 on: November 03, 2013, 10:58:35 PM »
I provided the downloaded article in that thread, but if anyone missed it, I am uploading it again.

I don't believe that human contact can result in such wide-spread occurrence of white spots on recent coins. In this article, two causes are given: chemical polishing, which does not involve chlorine; and cleaning agents, which do contain chlorine. I guess that the cleaning agents are used to clean blanks after annealing. When rinsing is incomplete, the cleaning agents will remain and lead to white spots.

Offline poconopenn

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Re: Possible WSOD explanation?
« Reply #40 on: November 04, 2013, 09:05:27 PM »


I don't believe that human contact can result in such wide-spread occurrence of white spots on recent coins. In this article, two causes are given: chemical polishing, which does not involve chlorine; and cleaning agents, which do contain chlorine. I guess that the cleaning agents are used to clean blanks after annealing. When rinsing is incomplete, the cleaning agents will remain and lead to white spots.

It is my understanding that no chloride compound is being using in the minting process, including blank preparation. The only place mentioned the potential source of chloride in this article is the cleaning solution used to keep the plant in a proper production environment(生产环境). In other words, the cleaning solution containing chloride is for housekeep purpose, not used in production process. In the conclusion of this article, the authors made the recommendation to dry the blanks longer to make sure that no trace of moisture left on the surface of the blanks, since chemical treated silver surface produces a rougher texture, therefore, more moisture will adhere to the surface.

The authors, for unknown reason, did not consider the effects of sodium, which is a highly corrosive chemical for most metals. The significant amount of sodium was found in the white spots, not only in this article, but also in previous two articles. The obvious source of sodium and chloride is from salt in the human fluid which can be introduced to the coin surface during the inspection. China Mint has claimed that 30% of coin produced were inspected manually.

Definitions of 生产环境:

http://baike.baidu.com/link?url=CuYxhZPpUCEs8TcGo-eRobqAK7nrkwyh0A2Qz3aac4N24boiYjV3yn9ARooXWFcLPHiYzLRFcU1lTDtnozNiNq


Offline fwang2450

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Re: Possible WSOD explanation?
« Reply #41 on: November 04, 2013, 09:48:08 PM »
It is my understanding that no chloride compound is being using in the minting process, including blank preparation. The only place mentioned the potential source of chloride in this article is the cleaning solution used to keep the plant in a proper production environment(生产环境). In other words, the cleaning solution containing chloride is for housekeep purpose, not used in production process. In the conclusion of this article, the authors made the recommendation to dry the blanks longer to make sure that no trace of moisture left on the surface of the blanks, since chemical treated silver surface produces a rougher texture, therefore, more moisture will adhere to the surface.

The authors, for unknown reason, did not consider the effects of sodium, which is a highly corrosive chemical for most metals. The significant amount of sodium was found in the white spots, not only in this article, but also in previous two articles. The obvious source of sodium and chloride is from salt in the human fluid which can be introduced to the coin surface during the inspection. China Mint has claimed that 30% of coin produced were inspected manually.

Definitions of 生产环境:

http://baike.baidu.com/link?url=CuYxhZPpUCEs8TcGo-eRobqAK7nrkwyh0A2Qz3aac4N24boiYjV3yn9ARooXWFcLPHiYzLRFcU1lTDtnozNiNq


My understanding of 生产环境 is different. I worked in a factory for more than 4 years. 生产环境 can mean the environment, or the entire production process. But if you have evidence that no chlorine products are used in acid cleaning (I have heard of nitric acid and sulfuric acid), my guess would be wrong.

Offline poconopenn

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Offline fwang2450

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Re: Possible WSOD explanation?
« Reply #43 on: March 23, 2016, 10:04:20 PM »
Thanks for sharing! But I wonder whether acetone will do the trick.

Offline KeepOnTrying!

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Re: Possible WSOD explanation?
« Reply #44 on: March 23, 2016, 10:38:38 PM »
Thanks for sharing! But I wonder whether acetone will do the trick.

Do you know of something else that will get rid of or reduce the density of the white spots? NCS is not going to share their secrets. So far they don't claim to get rid of white spots but that may be because they cannot guarantee 100% spot removal. I am interested in this issue!

Thanks.

http://china-mint.info/forum/index.php?topic=12247.msg72161;topicseen#msg72161
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Offline BubbaJones

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Re: Possible WSOD explanation?
« Reply #45 on: March 23, 2016, 10:40:17 PM »
I think if it did the trick word would have spread since this article came out?  

I'm skeptical.  And if it works, does it damage the coin.  

Has anyone tried it?  Maybe keep on trying should try it on those abysmal pandas he showed us pictures of.  

I have to admit, it has motivated me to not buy silver any longer, and just go with gold.  

I know gold has its own issues, but there is something grotesque about white spots/stains on a beautiful silver coin.  #sadface.

Offline KeepOnTrying!

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Re: Possible WSOD explanation?
« Reply #46 on: March 23, 2016, 11:07:49 PM »
I think if it did the trick word would have spread since this article came out? 

I'm skeptical.  And if it works, does it damage the coin. 

Has anyone tried it?  Maybe keep on trying should try it on those abysmal pandas he showed us pictures of. 

I have to admit, it has motivated me to not buy silver any longer, and just go with gold. 

I know gold has its own issues, but there is something grotesque about white spots/stains on a beautiful silver coin.  #sadface.

I agree to some extent that acetone may not be a magic cure but it has been used for amateur coin conservation especially after an olive oil bath. I suspect that the cure for white spots could be incremental. Until something else is suggested acetone will have to be one of the candidate reagents.

Yes, my purchase of non-gold coins and medals has almost screeched to a halt. It doesn't make sense that you will spend tons on silver coins only to see the value vaporize due to white spots!
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Offline poconopenn

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Re: Possible WSOD explanation?
« Reply #47 on: March 23, 2016, 11:15:23 PM »
Thanks for sharing! But I wonder whether acetone will do the trick.

Yes, acetone will not do the job. The milk spot is a mixture of inorganic compounds and not soluble in acetone.

As collector, I am interested in the following part of the article:

“Perhaps 50 or 100 years from now, American Silver Eagles from the 1980s and ‘90s that somehow remained flawlessly untouched by milk spots may be as scarce and desirable as Full Head Standing Liberty quarters or Full Bell Line Franklin halves.”

“Indeed, the day may come when numismatists willingly pony up hundreds of dollars for choice, spotless specimens of an otherwise common American Silver Eagle. Surely, heated debates will ensue in numismatic circles about deciphering “doctored” versus “original” American Silver Eagles, much like some Lincoln cent enthusiasts scrutinize decades-old “red” Lincolns for any sign of past dipping.”

Few years back, I posted in this forum, questioning the logical of about NCS conservation to prevent the formation of white spots on the fresh-made and spotless silver pandas. Perhaps, 10 or 20 years from now, the “original” and spotless silver panda will have a valuation much higher than NCS conserved coin. Time will tell.

Offline KeepOnTrying!

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Re: Possible WSOD explanation?
« Reply #48 on: March 24, 2016, 12:08:16 AM »
Yes, acetone will not do the job. The milk spot is a mixture of inorganic compounds and not soluble in acetone.

As collector, I am interested in the following part of the article:

“Perhaps 50 or 100 years from now, American Silver Eagles from the 1980s and ‘90s that somehow remained flawlessly untouched by milk spots may be as scarce and desirable as Full Head Standing Liberty quarters or Full Bell Line Franklin halves.”

“Indeed, the day may come when numismatists willingly pony up hundreds of dollars for choice, spotless specimens of an otherwise common American Silver Eagle. Surely, heated debates will ensue in numismatic circles about deciphering “doctored” versus “original” American Silver Eagles, much like some Lincoln cent enthusiasts scrutinize decades-old “red” Lincolns for any sign of past dipping.”

Few years back, I posted in this forum, questioning the logical of about NCS conservation to prevent the formation of white spots on the fresh-made and spotless silver pandas. Perhaps, 10 or 20 years from now, the “original” and spotless silver panda will have a valuation much higher than NCS conserved coin. Time will tell.


Respectfully then Poconopenn, what should a silver coin collector do now to ensure that he/she buys/stores silver coins that will not develop white spots in future or decrease the propensity for white spot formation?

Thanks for the wisdom and insight.

With best wishes.
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Offline NBM

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Re: Possible WSOD explanation?
« Reply #49 on: March 25, 2016, 08:14:26 AM »
I seem to recall reading on another forum about a snake oil treatment they had developed and would offer through a dealer in China but nothing seemed to come of it.
 :001_rolleyes:

Offline KeepOnTrying!

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Re: Possible WSOD explanation?
« Reply #50 on: March 25, 2016, 08:59:56 AM »
I seem to recall reading on another forum about a snake oil treatment they had developed and would offer through a dealer in China but nothing seemed to come of it.
 :001_rolleyes:

Yeah. We can reverse engineer that one too!  N17
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Offline KeepOnTrying!

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Re: Possible WSOD explanation?
« Reply #51 on: March 25, 2016, 09:14:04 AM »
Yes, acetone will not do the job. The milk spot is a mixture of inorganic compounds and not soluble in acetone.

As collector, I am interested in the following part of the article:

“Perhaps 50 or 100 years from now, American Silver Eagles from the 1980s and ‘90s that somehow remained flawlessly untouched by milk spots may be as scarce and desirable as Full Head Standing Liberty quarters or Full Bell Line Franklin halves.”

“Indeed, the day may come when numismatists willingly pony up hundreds of dollars for choice, spotless specimens of an otherwise common American Silver Eagle. Surely, heated debates will ensue in numismatic circles about deciphering “doctored” versus “original” American Silver Eagles, much like some Lincoln cent enthusiasts scrutinize decades-old “red” Lincolns for any sign of past dipping.”

Few years back, I posted in this forum, questioning the logical of about NCS conservation to prevent the formation of white spots on the fresh-made and spotless silver pandas. Perhaps, 10 or 20 years from now, the “original” and spotless silver panda will have a valuation much higher than NCS conserved coin. Time will tell.


So the candidate reagent will have to be an aqueous solution of something and not a hydrocarbon. Thoughts of descaling and deliming come to mind but initial examples are likely to be too caustic and will attack the underlying metal. Unless their concentration is reduced by serial dilution to the minimum effective level.
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Offline silverpv

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Re: Possible WSOD explanation?
« Reply #52 on: March 25, 2016, 10:09:04 AM »
I tried acetone on a panda privy maple and fudged it. It actually accelerated the white spot development. Ugh.. Didn't have white spots when I started but had them when I finished, plus it didn't work so well on the proof part.

Offline poconopenn

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Re: Possible WSOD explanation?
« Reply #53 on: March 25, 2016, 01:44:34 PM »
I tried acetone on a panda privy maple and fudged it. It actually accelerated the white spot development. Ugh.. Didn't have white spots when I started but had them when I finished, plus it didn't work so well on the proof part.

Most acetone in the stores are industrial grade which contains water and other impurities. The acetone used for silver coin cleaning has to be reagent (analytical) grade which has a purity of >99.5%. The water in the industrial grade will be left on the coin surface after acetone evaporated and promote the formation of the white spots.

Offline silverpv

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Re: Possible WSOD explanation?
« Reply #54 on: March 25, 2016, 01:51:50 PM »
Most acetone in the stores are industrial grade which contains water and other impurities. The acetone used for silver coin cleaning has to be reagent (analytical) grade which has a purity of >99.5%. The water in the industrial grade will be left on the coin surface after acetone evaporated and promote the formation of the white spots.

I used 100% pure acetone. It worked on gold with no issues, tried it on the pandas and boom! spots.. I might just do a video on it. I recorded it for posterity, either success but inevitably failure... lol. At least I tried! I also rinsed with distilled water but it was like an immediate reaction while submerged in the acetone. Quite amazing.. The things we do to test  hypothesises! I actually screwed up 5 panda privy's, what can you do. I still have melt and it is at least in a capsule.

It's actually not that bad, but you would notice it under a 5x loupe. It also left this weird residue that wouldn't come off..



Offline KeepOnTrying!

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Re: Possible WSOD explanation?
« Reply #55 on: March 25, 2016, 02:34:42 PM »
I used 100% pure acetone. It worked on gold with no issues, tried it on the pandas and boom! spots.. I might just do a video on it. I recorded it for posterity, either success but inevitably failure... lol. At least I tried! I also rinsed with distilled water but it was like an immediate reaction while submerged in the acetone. Quite amazing.. The things we do to test  hypothesises! I actually screwed up 5 panda privy's, what can you do. I still have melt and it is at least in a capsule.

It's actually not that bad, but you would notice it under a 5x loupe. It also left this weird residue that wouldn't come off..




You did all 5 coins at a time? Best to do one at a time and cut your losses. I haven't done any yet. I am still waiting for more concrete info. I'll do spot tests with a q-tip; treat some spots and leave others untreated followed by the rinse, and compare results. Where did you get the analytical grade acetone (no private info)? Thanks.

Looks like the photos did not load!
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Offline silverpv

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Re: Possible WSOD explanation?
« Reply #56 on: March 25, 2016, 02:46:33 PM »
not analytical grade, cvs grade.. lol.. 100% pure acetone nail polish remover. I did 1,3,1 and wasn't successful at any of the tries. I kept getting this strange residue that kept appearing.

Offline wg

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Re: Possible WSOD explanation?
« Reply #57 on: March 25, 2016, 03:14:31 PM »
Do you know of something else that will get rid of or reduce the density of the white spots? ( .. )

  "get rid of w. s."  
 :001_tongue:

Quote
*This official coin has been colored by a private company

http://www.ebay.de/itm/361511824158?_trksid=p2060353.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT




Offline Mirkkanen

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Re: Possible WSOD explanation?
« Reply #58 on: March 25, 2016, 03:24:21 PM »
w.g. types in riddles, but I think he is trying to promote the idea of colorizing your spotted coins!

Maybe this will help.

Offline BubbaJones

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Re: Possible WSOD explanation?
« Reply #59 on: March 25, 2016, 03:33:30 PM »
or you can just do this?  N27


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Re: Possible WSOD explanation?
« Reply #60 on: March 25, 2016, 03:55:00 PM »
@silverpv what exactly is the meaning of "it worked on gold with no issues" - removing red spots?
i did try pure aceton on silver maples, no effect even after 2 weeks full bath.
coin is still there, milkspot too

Offline silverpv

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Re: Possible WSOD explanation?
« Reply #61 on: March 25, 2016, 04:00:10 PM »
@silverpv what exactly is the meaning of "it worked on gold with no issues" - removing red spots?
i did try pure aceton on silver maples, no effect even after 2 weeks full bath.
coin is still there, milkspot too

It cleaned the gold a bit and brightened it up i didn't rub it or anything, just let it sit a 1926 $10 Indian.  I tried to do clean the panda privy before milkspots formed on the 2016, the idea was to soak it and try to remove the impurity before sending it off to grade but when I dunked it this white residue popped out out of nowhere on the coin and won't come off. So I had to scrap the idea of sending them in for grading. Two that weren't treated came back nicely, I was hoping to prevent milkspots and grade!

Offline Mirkkanen

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Re: Possible WSOD explanation?
« Reply #62 on: March 25, 2016, 04:18:22 PM »
Lesson learned?

Canada sucks!  N50


 :biggrin:

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Re: Possible WSOD explanation?
« Reply #63 on: March 25, 2016, 04:59:59 PM »
not analytical grade, cvs grade.. lol.. 100% pure acetone nail polish remover. I did 1,3,1 and wasn't successful at any of the tries. I kept getting this strange residue that kept appearing.

I am not saying that acetone is the candidate but if it is used it has to be the "analytic" grade or whatever USP grade that is free from impurities because this can cause extraneous effects. Even the water for rinsing will have to be of a certain standard of purity for example triple distilled reverse osmosis water or whatever the chemistry books say to use.
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Offline silverpv

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Re: Possible WSOD explanation?
« Reply #64 on: March 25, 2016, 05:07:27 PM »
I am not saying that acetone is the candidate but if it is used it has to be the "analytic" grade or whatever USP grade that is free from impurities because this can cause extraneous effects. Even the water for rinsing will have to be of a certain standard of purity for example triple distilled reverse osmosis water or whatever the chemistry books say to use.

Well, my understanding was pure acetone is 100% and has no additives. The water I used was distilled, not triple distilled but triple distilled reverse osmosis. lol. Either way, it cost me a few bucks to try to circumvent Royal Canadian Mints Security Feature and it didn't work.

I'm willing to experiment one more time and sacrifice a few more panda privies, this time with blitz and distilled water. I used it on E=mc2 and Britannias and they don't look like they are spotting after half a year. I have a tube of libertads where a few of them are spotting now. 2015's that I purchased around the same time but I cleaned the e=mc2'd.

Offline KeepOnTrying!

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Re: Possible WSOD explanation?
« Reply #65 on: March 25, 2016, 05:16:27 PM »
Well, my understanding was pure acetone is 100% and has no additives. The water I used was distilled, not triple distilled but triple distilled reverse osmosis. lol. Either way, it cost me a few bucks to try to circumvent Royal Canadian Mints Security Feature and it didn't work.

I'm willing to experiment one more time and sacrifice a few more panda privies, this time with blitz and distilled water. I used it on E=mc2 and Britannias and they don't look like they are spotting after half a year. I have a tube of libertads where a few of them are spotting now. 2015's that I purchased around the same time but I cleaned the e=mc2'd.

Yes, I was surprised to learn in advanced Chemistry that single distilled water was not pure enough for certain experiments and cell culture work.

However, regular supermarket ingredients will be most convenient. Perhaps it is the failure to identify the right reagent for the proposed work that is causing the problem and not necessarily the grade. But the important thing is that if your voodoo works please share.

Moonshine might be the preferred reagent in upcountry!  :thumbup:
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Offline KeepOnTrying!

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Re: Possible WSOD explanation?
« Reply #66 on: March 25, 2016, 05:19:46 PM »
or you can just do this?  N27



I am always filled with joy when I see this. Means the pool of MS70 contenders is shrinking fast!  N17

Anyone wants more crayola? It's free!  N16
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Offline poconopenn

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Re: Possible WSOD explanation?
« Reply #67 on: March 25, 2016, 06:03:17 PM »
Well, my understanding was pure acetone is 100% and has no additives. The water I used was distilled, not triple distilled but triple distilled reverse osmosis. lol. Either way, it cost me a few bucks to try to circumvent Royal Canadian Mints Security Feature and it didn't work.

I'm willing to experiment one more time and sacrifice a few more panda privies, this time with blitz and distilled water. I used it on E=mc2 and Britannias and they don't look like they are spotting after half a year. I have a tube of libertads where a few of them are spotting now. 2015's that I purchased around the same time but I cleaned the e=mc2'd.

I do not believe that nail polish remover is 100% acetone. The acetone will dry and damage the fingernail. It is my understanding that at least 20% water and other solvents are added to the fingernail remover for the purpose of retaining the moisture in the fingernails and surrounding skin.

Usually, hardware stores carry pure acetone as oil paint thinner.
 
Do not use any type of water to rinse the coin after dipping in the acetone. Pure acetone will evaporated quickly without leave any residue. The only purpose of dipping into acetone is to remove the moisture and any oily material which may adhere to the coin surface during the minting, inspection and packaging. Additional contact of water will only cause the formation of white spots. Of course, you can always rinse coin with “fresh acetone” again after dipping.  The dry, clear and dark environment will retard the formation of white spots. Acetone itself will not react with silver, but the impurities will.

Offline silverpv

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Re: Possible WSOD explanation?
« Reply #68 on: March 25, 2016, 06:08:33 PM »
I do not believe that nail polish remover is 100% acetone. The acetone will dry and damage the fingernail. It is my understanding that at least 20% water and other solvents are added to the fingernail remover for the purpose of retaining the moisture in the fingernails and surrounding skin.

Usually, hardware stores carry pure acetone as oil paint thinner.
 
Do not use any type of water to rinse the coin after dipping in the acetone. Pure acetone will evaporated quickly without leave any residue. The only purpose of dipping into acetone is to remove the moisture and any oily material which may adhere to the coin surface during the minting, inspection and packaging. Additional contact of water will only cause the formation of white spots. Of course, you can always rinse coin with “fresh acetone” again after dipping.  The dry, clear and dark environment will retard the formation of white spots. Acetone itself will not react with silver, but the impurities will.


There are two types of nail polish remover, one has the stuff you mention, the other is 'pure' acetone. They talked about it in other forums. It does evaported very quickly and dried. The first time I did not rinse with water. Then I tried it with distilled water. I tried several permutations but the white spot presented while submerged in acetone and wouldn't come off.

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Re: Possible WSOD explanation?
« Reply #69 on: April 01, 2016, 01:26:06 PM »
What will happen with the mirroed spaces on the coin?