It's not like if you have some silver chloride in a clear jar and put it in sunlight that it goes poof and you end up with silver and chlorine.
To be clear, the milk spots COULD be silver chloride. But they can not be caused by the presence of silver chloride PRIOR TO THEIR APPEARANCE.
There would have to be another agent present. Possibly bleach. Bleach is capable of oxidizing silver to silver ion, but the chemistry would need to be more complicated to end at silver chloride.
There was no oxygen like might be found in bleach which is hypochlorite.
No oxygen where or when?
If they had an accurate chemical analysis of the surface, there wouldn't be any mystery would there?
All comments reflect the opinion of the author, evn when irrefutably accurate.
It's not like if you have some silver chloride in a clear jar and put it in sunlight that it goes poof and you end up with silver and chlorine.
To be clear, the milk spots COULD be silver chloride. But they can not be caused by the presence of silver chloride PRIOR TO THEIR APPEARANCE.
There would have to be another agent present. Possibly bleach. Bleach is capable of oxidizing silver to silver ion, but the chemistry would need to be more complicated to end at silver chloride.
It could be a latent form of silver chloride or some chlorine species which requires time or exposure to light or moisture to become visible as silver chloride. I said the white spots that you can see are silver chloride since all we found to be present was chlorine/chloride species. Any precursors to that may or may not be a different form of AgCl. You have to remember too that species bound to say a metal surface behave differently than the same species in a jar or in a solution.
That's why I say that the subject needs additional study to find out what the hell is going on. I made an effort to find out. Nobody else did chit AFAIK.
BTW here is a link to what I found for AgCl. There is an email addy there if you want to ask about solubility changes after exposure to light.
To be clear, the milk spots COULD be silver chloride. But they can not be caused by the presence of silver chloride PRIOR TO THEIR APPEARANCE.
There would have to be another agent present. Possibly bleach. Bleach is capable of oxidizing silver to silver ion, but the chemistry would need to be more complicated to end at silver chloride.
There was no oxygen like might be found in bleach which is hypochlorite.
It is also notoriously difficult to impossible to see oxygen (or any element below atomic number 11) in an X-ray analysis.
It's not like if you have some silver chloride in a clear jar and put it in sunlight that it goes poof and you end up with silver and chlorine.
To be clear, the milk spots COULD be silver chloride. But they can not be caused by the presence of silver chloride PRIOR TO THEIR APPEARANCE.
There would have to be another agent present. Possibly bleach. Bleach is capable of oxidizing silver to silver ion, but the chemistry would need to be more complicated to end at silver chloride.
It could be a latent form of silver chloride or some chlorine species which requires time or exposure to light or moisture to become visible as silver chloride. I said the white spots that you can see are silver chloride since all we found to be present was chlorine/chloride species. Any precursors to that may or may not be a different form of AgCl. You have to remember too that species bound to say a metal surface behave differently than the same species in a jar or in a solution.
That's why I say that the subject needs additional study to find out what the hell is going on. I made an effort to find out. Nobody else did chit AFAIK.
BTW here is a link to what I found for AgCl. There is an email addy there if you want to ask about solubility changes after exposure to light.
Could you define "latent form of silver chloride"? That is a fancy way of saying something that is NOT silver chloride.
I agree that the white spots may well be silver chloride. But, since they form over time, their formation is due to something NOT silver chloride or they would be white all along.
All comments reflect the opinion of the author, evn when irrefutably accurate.
To be clear, the milk spots COULD be silver chloride. But they can not be caused by the presence of silver chloride PRIOR TO THEIR APPEARANCE.
There would have to be another agent present. Possibly bleach. Bleach is capable of oxidizing silver to silver ion, but the chemistry would need to be more complicated to end at silver chloride.
There was no oxygen like might be found in bleach which is hypochlorite.
It is also notoriously difficult to impossible to see oxygen (or any element below atomic number 11) in an X-ray analysis.
All I know is what we found looking at spotting on one coin. Dan Carr said it was bismuth from grease, but there was none of that and the stuff wouldn't come off with ammonia or cyanide solutions.
A surface chemical examination of the planchets would be in order. Also a tour of the minting facility should be useful as well. It can't be that hard to figure out. FWIW the gal who was head of QC for the mint a number of years ago said it was silver chloride too so you thought they would have figured it out.
One member here toured the West Point facility, but would never say if they were shown parts of the process where the coins or blanks were exposed to cleaning and/or rinsing steps.
One could also try to access mint purchasing records to see if they are buying quantities of bleach, hydrochloric acid or other chemicals.
How long does it take on average for the milk spots to start appearing? I just looked at 10 ASE's from 2017 and all of them were fine. Does it take longer than about 2 years? Does it happen to ASE's in OGP? Or is it directly linked to after being slabbed?
It's not like if you have some silver chloride in a clear jar and put it in sunlight that it goes poof and you end up with silver and chlorine.
To be clear, the milk spots COULD be silver chloride. But they can not be caused by the presence of silver chloride PRIOR TO THEIR APPEARANCE.
There would have to be another agent present. Possibly bleach. Bleach is capable of oxidizing silver to silver ion, but the chemistry would need to be more complicated to end at silver chloride.
It could be a latent form of silver chloride or some chlorine species which requires time or exposure to light or moisture to become visible as silver chloride. I said the white spots that you can see are silver chloride since all we found to be present was chlorine/chloride species. Any precursors to that may or may not be a different form of AgCl. You have to remember too that species bound to say a metal surface behave differently than the same species in a jar or in a solution.
That's why I say that the subject needs additional study to find out what the hell is going on. I made an effort to find out. Nobody else did chit AFAIK.
BTW here is a link to what I found for AgCl. There is an email addy there if you want to ask about solubility changes after exposure to light.
Could you define "latent form of silver chloride"? That is a fancy way of saying something that is NOT silver chloride.
I agree that the white spots may well be silver chloride. But, since they form over time, their formation is due to something NOT silver chloride or they would be white all along.
The latent form of silver chloride would be simply the presence of the components necessary to produce silver chloride if certain conditions were met to be favorable to its formation. That is both silver [ionized or otherwise] and chloride would be present and waiting for the right conditions to produce silver chloride. Call it imminent silver chloride if you want. They aren't white until the ARE AgCl.
@DotStore said:
How long does it take on average for the milk spots to start appearing? I just looked at 10 ASE's from 2017 and all of them were fine. Does it take longer than about 2 years? Does it happen to ASE's in OGP? Or is it directly linked to after being slabbed?
No clue, but a few years back one or 2 of the coins in my 20th anniv set were ruined and I have not looked at them since. Some are spotted right in mint tubes from monster boxes. Some spot in the holder/s. Happens in both NGC and PCGS holders. Can't say I've ever seen it on current commem issues from the mint tho.
In one of the videos put out by the mint you can see them putting some sort of oil on the edges of stacks of planchets before they go into the press to be struck. Nothing said or shown about how or if it is removed.
"My friends who see my collection sometimes ask what something costs. I tell them and they are in awe at my stupidity." (Baccaruda, 12/03).I find it hard to believe that he (Trump) rushed to some hotel to meet girls of loose morals, although ours are undoubtedly the best in the world. (Putin 1/17) Gone but not forgotten. IGWT, Speedy, Bear, BigE, HokieFore, John Burns, Russ, TahoeDale, Dahlonega, Astrorat, Stewart Blay, Oldhoopster, Broadstruck, Ricko, Big Moose, Cardinal.
I'm enjoying your posts. Keep teaching. Perhaps after it is done we and make a simple summary all in one place.
My gut feeling is that it's an artifact of the production process either during planchet/blank preparation or after the mint receives the blanks. Without knowing everything about the process, it's difficult to be more definitive. An analytical study of the blanks and finished coins could yield some clues.
Comments
No oxygen where or when?
If they had an accurate chemical analysis of the surface, there wouldn't be any mystery would there?
All comments reflect the opinion of the author, evn when irrefutably accurate.
perthmintbullion.com/us/blog/blog/15-01-05/Perth_Mint_Tackles_Milk_Spot_Issue.aspx
All comments reflect the opinion of the author, evn when irrefutably accurate.
https://thesilverforum.com/topic/10217-close-up-view-and-chemistry-of-the-milk-spots/
All comments reflect the opinion of the author, evn when irrefutably accurate.
It could be a latent form of silver chloride or some chlorine species which requires time or exposure to light or moisture to become visible as silver chloride. I said the white spots that you can see are silver chloride since all we found to be present was chlorine/chloride species. Any precursors to that may or may not be a different form of AgCl. You have to remember too that species bound to say a metal surface behave differently than the same species in a jar or in a solution.
That's why I say that the subject needs additional study to find out what the hell is going on. I made an effort to find out. Nobody else did chit AFAIK.
BTW here is a link to what I found for AgCl. There is an email addy there if you want to ask about solubility changes after exposure to light.
https://saltlakemetals.com/contact/
It is also notoriously difficult to impossible to see oxygen (or any element below atomic number 11) in an X-ray analysis.
https://myscope.training/legacy/analysis/eds/quantitative/
All comments reflect the opinion of the author, evn when irrefutably accurate.
Could you define "latent form of silver chloride"? That is a fancy way of saying something that is NOT silver chloride.
I agree that the white spots may well be silver chloride. But, since they form over time, their formation is due to something NOT silver chloride or they would be white all along.
All comments reflect the opinion of the author, evn when irrefutably accurate.
All I know is what we found looking at spotting on one coin. Dan Carr said it was bismuth from grease, but there was none of that and the stuff wouldn't come off with ammonia or cyanide solutions.
A surface chemical examination of the planchets would be in order. Also a tour of the minting facility should be useful as well. It can't be that hard to figure out. FWIW the gal who was head of QC for the mint a number of years ago said it was silver chloride too so you thought they would have figured it out.
One member here toured the West Point facility, but would never say if they were shown parts of the process where the coins or blanks were exposed to cleaning and/or rinsing steps.
One could also try to access mint purchasing records to see if they are buying quantities of bleach, hydrochloric acid or other chemicals.
Sounds like they are saying that a USO Unidentified Sitting Object is sucking chlorine out of the air and changing it to silver chloride.
Not much to see there.
How long does it take on average for the milk spots to start appearing? I just looked at 10 ASE's from 2017 and all of them were fine. Does it take longer than about 2 years? Does it happen to ASE's in OGP? Or is it directly linked to after being slabbed?
The latent form of silver chloride would be simply the presence of the components necessary to produce silver chloride if certain conditions were met to be favorable to its formation. That is both silver [ionized or otherwise] and chloride would be present and waiting for the right conditions to produce silver chloride. Call it imminent silver chloride if you want. They aren't white until the ARE AgCl.
@BAJJERFAN
@jmlanzaf
I'm enjoying your posts. Keep teaching. Perhaps after it is done we and make a simple summary all in one place.
No clue, but a few years back one or 2 of the coins in my 20th anniv set were ruined and I have not looked at them since. Some are spotted right in mint tubes from monster boxes. Some spot in the holder/s. Happens in both NGC and PCGS holders. Can't say I've ever seen it on current commem issues from the mint tho.
In one of the videos put out by the mint you can see them putting some sort of oil on the edges of stacks of planchets before they go into the press to be struck. Nothing said or shown about how or if it is removed.
I've solved the issue - just avoid ASE's.
Or if you do indulge just resell the roll without ever opening it.
My gut feeling is that it's an artifact of the production process either during planchet/blank preparation or after the mint receives the blanks. Without knowing everything about the process, it's difficult to be more definitive. An analytical study of the blanks and finished coins could yield some clues.