Milk spots are a bummer. It is my understanding that you can't get rid of them, but this is not my series. I don't know if PCGS has any gurantees on this stuff. I tend to doubt it, but you might ask.
I believe that the change in holder speeds up the spots. The proof half dollars in 1964 had the same problem. I understand the services can reduce the size of the spots but they will come back.
I still don't understood why "milk spots" have become such an issue on bullion coins. They never had issues when they minted them for circulation.
A “bullion coin” is not a bullion coin when it is Proof. Proof coins have value beyond the normal bullion premium. Proof coins have reputation for perfection or close to it. Therefore any imperfection is important and lowers the value of the coin.
This is new to me. Why would they slap that label on the back at draw more attention to it instead of a call or email?
One can make an argument that precious metal coins that are not minted for true circulation are "bullion" coins regardless of their finish especially proof coins which are produced specifically for collectors and not meant for circulation. Regardless, my point is older precisions metal coins that were produced for circulation don't seem to have issues wit milk spots.
Proof bullion coins are issued to be collectors' items. They might prove to be nothing but bullion if the collector market for them dies, but so far as the mint is concerned, they are collectors' items when the facility issues them. The premium prices that the mint charges from Proof American Silver Eagles proves that. So far as the milk spot issue goes, it must have something to do with the chemicals the mint uses to clean planchets. If the cleaning agent is not properly rinsed a residue remains which apparently damages silver. Back in the day, the mint seems to have used something else on Proof coins, but it used other agents that toned coins. For example many Mint State 1912-S nickels are toned to one degree or another. The coin is seldom found in its original bright white form unless it’s been dipped or cleaned. The San Francisco Mint must have used something on them that caused that.
Yes, that's my point. Silver coins minted from the 60's and earlier didn't have milk spot issues. Even the coins minted in the early eighties didn't have issues. This has become a major problem in the past couple of decades. It seems to be a problem regardless of what country is minting them although Canadian coins seem to be the worst.