What ever came about on D Hall's $50,000 reward to address milk spots
jessewvu
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It seems that silver coins could last years in their original US Mint capsules, but something about opening them up, spots develop.
I had cashed in on the buy back over a decade ago on some high grade modern rarities, felt bad doing it but business is business I suppose.
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From what I understand, opening up a capsule is not the primary reason for milk spots. It has something to do with the final rinse performed at the different Mints. It also affects numerous other world wide mints with their silver coins. I do not believe a reward has been paid to find a solution after a coin "comes down" with milk spots.
I thought it was $10K
I thought it was.....
So-called "Milk Spots" on silver coins is actually a form of corrosion. The metal surface is permanently etched by the process. So there is no undoing it. The only way to remove them is to polish the coin (which, of course, is entirely detrimental).
But the question of how to prevent them from forming in the first place is an important consideration. I believe that properly "dipping" a Silver Eagle will inhibit future milk spot formation.
Some theorize that milk spots are a result of the planchet being poorly rinsed so any residue on the planchet is actually struck into the surface of the coin so I'm not sure dipping will totally prevent the milk spotting.
Worry is the interest you pay on a debt you may not owe.
"Paper money eventually returns to its intrinsic value---zero."----Voltaire
"Everything you say should be true, but not everything true should be said."----Voltaire
Peace dollars seem to have more surface "ghosts" than other dollars that will not come off.
In the early 2000's, when there was a lot of discussion about milk spots, Russ told me that dipping ASE's in acetone soon after receipt, would prevent milk spots. I did that and none of my ASE's spotted. Now, I have no idea how he had discovered that, and certainly has no effect once the milk spots appear. However, I continue to do that and have not had the problem. Cheers, RickO
Come on, @ricko! We all know your coins are too afraid to spot, tone, or tarnish!
See http://www.doubledimes.com for a free online reference for US twenty-cent pieces
@astrorat....
Right - Bold, bright and brash.... and they better stay that way.... 
Cheers, RickO
Silver Canadian Maples are the worst for spotting.
No Way Out: Stimulus and Money Printing Are the Only Path Left
Thank you for this thread, which reminds me why I do not purchase high-grade silver Eagles nor Maples. Among others.
If my memory recall is correct I do believe Mr. Hall did meet with Mint officials for a discussion about spotting but I don't recall the meeting outcomes were ever discussed - publicly.
WS
It soured.
This is the correct answer. That assumes that by dipping your mean soaking in a solvent like acetone or distilled water.
As far as I know, most planchets have been treated by weak acid prior to striking going back as far as I've studied coins. This removes surface contaminants, etches the surface of the planchet, and creates a nice, clean surface. If any acid residue were to be left over, it would eventually corrode the coin with help from atmospheric moisture. I don't know the current pickling, or acid treatments, applied and how they might go wrong at the mint itself. However, I do know that if you have a clean, silver surface without contaminants, then you won't get spotting or etching with proper coin storage. So the best solution is to rinse the coins with something that could remove any residual residue. If the coin is still in OGP and you don't want to break it out, then it's Sophie's choice.
IG: DeCourcyCoinsEbay: neilrobertson
"Numismatic categorizations, if left unconstrained, will increase spontaneously over time." -me
Also on silver coins of lesser silver content it would "pickle" the surface and surface layer silver content would increase. Brits did this after going to 0.500 silver from the 0.925 in 1920.
Well, just Love coins, period.
Mainly about Sacajawea coins, but gives info on what chemicals are used on coins and coin presses. Maybe it will provide some clues
https://www.researchgate.net/profile/Tony-Ying-2/publication/263222095_Nanotribology_Application_in_the_Coining_Industry_I-Turn_off_Stamping_Oil_Sprayer_during_Coining/links/5d5d5382a6fdcc55e81e8609/Nanotribology-Application-in-the-Coining-Industry-I-Turn-off-Stamping-Oil-Sprayer-during-Coining.pdf
Mr_Spud
Since I don't have a clue as to how a raw coin was handled before I received it, I acetone every one. I have yet to see spots on any of my Dansco raw eagles. But, then maybe it's the dry Mojave air that keeps the milk babies away.
bob
Not anymore,,,,,,,
agree not the more recent ones. What changed? There lies the answer to the cause.
No Way Out: Stimulus and Money Printing Are the Only Path Left
Here is a video about the removal of spots from Canadian maples. H+e says that the spots are from borax. That's a whole nuther game because borax is likely physically bonded to the surface instead of chemically bonded.
Some years ago I worked with a scientist at the Ames Lab, US DOE. We determined that the whitish spots were due to chloride so most likely silver chloride. No other common elements were found. It would make sense that somewhere in the manufacturing process the silver blanks may have had spots of oxide as silver oxide. When washed with hydrochloric acid the oxide could be converted to silver chloride. Silver chloride does some strange things when exposed to light which results in something that is insoluble in almost everything. The spots are not removed with ammonia solution I can tell you that much. There are a lot of spots that are round in appearance which suggests that they were formed from small droplets of some solution that was deposited on the blanks and eventually evaporated. Also there spots which appear to be tea colored suggesting that there is more than one cause of the spotting.
There was an observation posted here a number of years ago that apparently flew over the heads of many here. It was said that one could see the incipient spots by shining a halogen flashlight onto the coins surface. If one dipped the coin in E Zest before the spots became visible they could be removed. Once visible the spots were pretty much permanent and you were SOL.
Lastly a number of years ago i was in contact with the Director of Quality Control for the mint and the B P&E. She said that they were addressing the problem and were going to purchase instrumentation [why that particular instrument I do not know] but this was during the Government sequestering and the purchase was on hold. Wasn't long after that that she moved on to a bigger and better Government position.
In one of the numerous online videos about the striking of silver eagles they stack the planchets in trays and you can see where they rub the the edge surface of the stacks with some kind of oil, but they don't show it being removed.
That would be for lubrication purposes, so that the struck coins would slide out of the collar easier, after being struck.
Obviously, but I doubt that the oil is the source of the spotting. Do you know what the oil is? They don't show them oiling the back edge of the stack, just the front. The video that I recall is on another computer so I won't search for it. At one time you mentioned bismuth grease here. We didn't find bismuth on the coin we examined.
It shouldn't be THAT hard to brainstorm the process from the time the planchets are unpacked until they are struck into coins to figure out where the spotting comes from, unless the contamination is already present from the supplier. If the spots contain chloride then look at the steps where chloride is used and removed. A more effective means of washing the planchets would be to trickle them down something like a 60 foot column of agitated rinse water [so they get 100% rinse] instead of dipping a basketful into a tub of water and calling it good.
If the contaminant contains chloride [and silver of course] and nothing else then the only reasonable source is hydrochoric acid.
What a shame that PCGS chose to eat so much money for a problem that was/is none of their doing. I don't know what help they got in attacking the problem, but I wonder if they determined what it was that they had to look for. How can you tell if your holder is contributing to the problem if you don't know what the contaminant is?
This is what the proper technique for evaluating the contaminant is.
https://en.wikipedia.org/wiki/X-ray_photoelectron_spectroscopy
If the contaminant contains chloride and your slab material doesn't then that would be end of story. The fact that spotted coins are in the tubes that come from the mint would tell me that it's not my problem.
A beam of Argon cations will remove the spots.
PS, It probably doesn't work very well on silver, but is OK for the milk spots on clothes.
My US Mint Commemorative Medal Set