My 1985,1986 and 1987 proof sets have developed cloudiness, particularly of the half dollar and the quarter. See pictures. I've replaced the sets with unblemished ones. The questions I have are: 1) Has anyone seen this kind of cloudiness or know the cause? 2) Since the set isn't worth much, would it make sense to try to clean the coins, and if so, how would you do it?
It looks like humidity. You might want to try putting them in a dry place, or in a slightly warm place (I'd put them on top of my cable box, just a tiny bit warm) and see if it goes away.
I have seen this quite often on proof sets. The cause if I'm not mistaken is due to a change atmosphere. Dry to damp, hot to cold. Unfortunatly the only thing you can do at this point is to trade\buy a new set or remove coins from case and do a quick dip on them (not the penny though). If you have no experience with dipping coins you can ruin them forever, so replacing them might be you best option since the set is not an expensive one.
It is believed that the haze on Proof sets is caused by the washing process done at the mint. Yes it can be removed by dipping, but quite often it comes right back. The best bet is to just replace them.
I think putting them in a warm place like on top of your cable box is a bad idea and if anything will just make the problem worse. A cooler, dry place is the best for your coins.
Thanks for the suggestion. It's hard to see in the picture, but the cloudiness or haze is definitely dry. It appears to be a residue from something. The nickel has spots, so it might be humidity that dried in the past. I don't see a solution short of taking the coins out of the case.
What about modern commemoratives? Are they safe is the original mint packaging or better to be moved to air tites or Intercept sheilds before they develope any haze?
If it's going to show up at all haze usually develops in the first couple of years, sometimes much faster. But if it there on a coin or set a couple of years old, then it's not likely it's going to. Even with proper storage, haze will develop on the coins that are going to get hazy. That's because what causes the haze happened at the mint - not because of the way they were stored. And cool, dry and consistent temp is the best for storage.
The haze on modern proof sets seems to be confined to Proof Sets , Proof Silver American Silver Eagles from around 1986-1991 or so. Some of the proof commemerative dollars from this era are also common with hazing. I agree with GDJMSP that a US Mint washing process of planchets at the time was responsible for this. Gold commemoratives from this time frame also seem to have a high incidence of spotting or toning apparently from the same improper washing process of planchets from the mint at the time.
