For the Lincoln cent folks-- black spots, haze, and strange discoloration

Longacre

This sounds like a medical question, but it is about Lincoln cents. I finally had a chance to get to the safe deposit box to take another look at a set of Lincoln cents that my cousin gave to me at least 20 years ago. They are in one of those albums with the plastic slides. On some of the more recent ones, mainly the proofs that I bought from a local coin shop when I was an early teen, I noticed some problems:

(1) On some of the proofs, there are now big black spots/flakes on some of the coins. On one coin, the spot is large enough to cover the "G" in God, just to give you a size reference.

(2) On the 1979-S "small date" proof, it is developing a haze in the right obverse field near the rim. Is this normal for a coin kept in an album?

(3) I have another 1979-S proof which I think is the large date (or is it large "S"?). Anyway, the "S" looks just like a blob and it is really hard to make out the S. Is this normal?

(4) On one of the coins from the 1970's (I don't think it is a proof), it has this weird spot behind Lincoln's head. It is white with very small green speckles in it. It looks like it is eating into the metal. Is this PVC damage?

The set is from 1943 to around the late 1980's. All of the coins are in MS condition or so. I don't think the set has much value, but I was curious about these questions above.

WheatFanatic

copper seems to be very reactive in my experience so i'm not suprised. i've heard that the copper used for the lincoln pennies also varies alot by impurities in the metal, which might contribute to the instability as well. those spots could have also been caused by a sneeze or cough or other mouth moisture from when you first had them out years ago and it formed into a corrosion spot.

Murphy

That's right. If copper was 100% pure and fingers never touched the surface before inserting them in safe flips, then we wouldn't see them corrode or even tone. But we salt water from our fingertips and the air itself may deposit moisture and other corrosive causing agents on our coins. There's not a whole lot you can do after you place them in storage.
Before I store coins I wipe them with a soft cotton cloth to get all the moisture & oil off their surface. The cloth I have been using safely is the inside of a sweatshirt that I cut up. I've tried Q-Tips, Kleenex, all those things are a BIG NO-NO! The inside of a sweatshirt is the only cotton cloth I will ever use to wipe my coins with. I then insert them in a good museum quality 2x2 flip for safekeeping. I haven't noticed any of the coins "turning" that I have used this procedure on. And I haven't scratched any coins with the sweatshirt cloth either.