Let me start by saying that I really like the artistic designs behind Provident's "Four Horsemen of the Apocalypse" series, which are quite elaborate and stunning. I purchased each piece as it came out directly from Provident. I look at the set every now and then and recently, I noticed a couple of "milk spots" on one of them. I'm not sure if I'm using the correct term for the discoloration and if not, please let me know. If you take a closer look at the piece, you'll notice two spots: one by the tail of the Black Horse and another, smaller one beneath the letter "E" in FAMINE. Here are my questions: 1. Are these milk spots and will they get worse? 2. What causes them? I'm in Florida but the room my coins are kept in is fully air-conditioned with very low humidity. I've seen ads wherein NCS stated that they can "conserve" coins and then transfer them to NGC for grading, but it appears that such services are more relevant to mainly older and more valuable coins. 3. If the spots proliferate, what is your advice? Does anyone here have any similar experience with sending (relatively) new coins to NCS for "cleaning" and then to NGC for re-holdering? As always, any feedback that you give is appreciated and thanks to all in advance for your help and input. If the spots do not get worse, I'll probably just leave well enough alone.
Milk spots can't be fixed. In fact, I think there is a 'bounty' out there, for anyone who can come up with a way to eliminate them......
1 - maybe, on both counts. First count, are they or aren't they ? I can't say for sure in this case. Second count, milk spots can and often do appear long after a coin has been slabbed. So yes, if those are milk spots, more may appear - or not. The important thing is, nobody has ever found any way to safely remove them. Quite true. A lot of light colored spots on coins that people think are milk spots - are not milk spots. They are actually saliva spots, and those can be safely removed, and rather easily. And in some cases, like the one in this thread, the only way to find out if it is a milk spot or a saliva spot - is to try and remove it. The result determines the answer. PCGS offered the reward to anyone who could find a way to safely remove them, to the best of my knowledge it still stands. And it was $25k.
Is it a milk spot? Maybe, but I personally wouldn't crack it out of a NGC slab graded PF 70 Ultra to find out. Yes, it probably distracts from it's beauty for you, but most collectors know that it probably can't be cleaned away.
That is why it is good to buy coins that have been in a holder for 10+ years. That way, if there was going to be milk spots, they would have already occurred. Would potentially save someone thousands of dollars on conditional rarities. Try to sell a PR70 with milk spots.
This was the third medal of the series and (in my opinion) not one of the best designs. So if you think this one is nice, have a look at the first two (White Horse of Conquest and Red Horse of War). THOSE are REALLY nice and they got me hooked on this series. If this medal were to be the first, it would probably not have captured my interest.
The spot by the tail does not appear to be a milkspot. It appears to have a speck of foreign material on the coin, probably organic, and it has reacted with the metal around it. Yes, that can be at least partially corrected by NCS, but they may not be able to remove it completely, and there may be some damage to the field below the foreign material.
If the coin is valuable enough or means a lot to you, it's worth sending to NCS. They may or may not be able to conserve it. They handle recently issued coins a lot. If you want to see some examples, look at Numistacker's videos on youtube. The Canadian mint has developed a process called Mintshield to eliminate or reduce milk spots on the coins they mint. See link. I don't think anyone else has it and don't think it can be used on existing coins. Cal http://www.numismaticnews.net/buzz/canada-gets-milk-spots-off-coins
I just wonder if it actually works - time will tell I guess. In effect it's a coating that's applied to the coins after they are struck. Years ago the US Mint experimented with several coatings, finally settling on one, for Sackys to stop or at least help stop their discoloration. It failed miserably. And I seem to recall reading or hearing about their experimenting with coatings to solve the problem with ASEs, but I've never heard of anything actually being effective. I think part of the problem is that coatings on the coins don't solve the real issue because whatever it is the issue apparently occurs in the underlying metal - not on top of the metal. And I say this because if it were just on top of the metal then you should be able to safely remove it. The fact you can't remove it, that indicates it's in the underlying metal. Personally, I suspect the problem lies somewhere in the modern smelting and refining process. And I say this because it's a problem that didn't used to even exist. It just suddenly appeared one day and has been with us ever since.
Doug, I think you're likely right about this. The problem hardly exists on 19th century silver proofs. It's also possible that the causal mechanism is in modern planchet manufacturing and handling methods. Components in droplets of hydraulic fluid or lubricant may react with silver quickly, but initially invisibly. These initial reactants become part of the surface or subsurface metal. Planchet cleaning doesn't remove them. Later the reaction progresses to a visible stage. Modern hydraulic fluids and lubricants are different chemically from those used as late as the middle of the 20th century. They often contain silicones and synthetic hydrocarbons, detergents, anti-biologicals, etc. Just a theory. Cal
