Milk spots on Silver coins

[KMAG100]

My question is can milk spots occur or appear from environmental exposure over time or are they caused by the minting process? I have read several posts, but it has not been clear to me. I originally was under the assumption that milk spots occurred from the minting process and toning was the environment's influences on the coin? Any comments or directions to information would be helpful and greatly appreciated.

[AHFreak]

I deal a lot with 1964 and earlier proofs. the 64 Kennedys are plagued with "milk spots". I am no expert, but here is what I "think" I have found.

 

First of all, at this point, I think there are two different types of "milk spots". One being the product of whatever minting process where some sort of acid sort of "etched" into the surface of the coin, over time. Those are there to stay, and from what I understand there is no safe way to remove them.

 

The second type can be "improved" and in some cases removed safely by experts, NCS is amazing based on what I know. Im not sure what these ones are, I was told once that it was PVC but I have no idea....

 

That's what I know about milk spots on silver.

 

 

[CentMania-migration]

I recently got a 1963 proof set, and they have milk spots. I'm not sure how much it affects the value, but it sure takes away from the looks!

[mmissinglink]

Hi,

 

The issue of milk spots on recently (last 10 years?) minted silver coins appears to be a problem related to the planchet (coin blank) production process.

 

According to a recent article ( https://www.texmetals.com/news/the-origin-of-mint-made-defects-on-bullion-coins/ ), the likely source of the development of milk spots on many recent silver coins is a lubricant that has been introduced recently into the planchet production process.

 

If it is true that the problem is lubricant that is not thoroughly washed off, then I am convinced by the resourcefulness and ingenuity that the human species possesses that removal of these milk spots without any visibly noticeable signs of removal is possible. Tens or hundreds of thousands of treasured silver mirror proof coins (slabbed and raw) are probably affected, as well as bu coins (but spots are much more noticeable on mirror proof surfaces). I am in communication with many coin collectors who would pay good money to have many of these treasured proof coins conserved as to have the spots removed if it could be done so that no signs of removal are visible.

 

I can only imagine the fortune that would be made were someone / some company to be able to devise a process that could effectively remove milk spots from mirror proof surfaces without any side effects of that process to be visible on the coin. What needs to happen is that research into this be stepped up dramatically. If only from a ROI vantage, this is a most worthwhile project to undertake.

 

I look forward to hearing of breakthroughs on this matter from NCS or other firms looking to resolve one of the most vexing issues confronting the countless collectors of modern silver coins.

 

 

.

[Conder101]

If the spots are caused by traces of the lubricant remaining on the planchet at the time of strike you have the fact the traces are struck into the surface of the coin. Also since the spots normally appear over time you have two possibilities, either the lubricant is oxidizing or reacting with something in the air, or with prolonged contact the lubricant is reacting with the metal surface of the coin.

 

If it is a case of the traces being struck into the surface, even if it can be removed there may still be evidence left on the surface.

 

If it is oxidizing lubricant there might be a possibility of a solvent that can remove it, but it also has to be something that doesn't affect the metal of the coin.

 

f it is the lubricant traces reacting with the metal of the coin then even if the lubricant is removed it will still leave the damaged surface behind (like PVC damage does. You can remove the PVC residue, but if it has damaged the surface the damage is forever.)