I learned something today regarding ANACS slabs that I'd like to share. The more experienced senior members here may already know, but for the sake of those newer to the hobby (like me), I figured I'd make this post. Among my hand-me-down collection are numerous slabbed coins - most by NGC and PCGS, and a few from ANACS. I noticed something that only pertains to the ANACS slabs. I see what looks to be "moisture bubbles" in the "donut" section of the slab, surrounding the coins. Here's what I mean: If you look around the cents, you'll see a "bubble ring" and on the left penny, at the 12 o'clock position all the way at the top, you'll see more "bubbles." If you press down on them, they actually can move a bit. They don't always take the shape of a ring around the coin. On this slab, they're spread out randomly. I've always assumed it was moisture that had seeped in and that there was nothing I could do. I chocked it up to tough luck. But then in January, I was given a Mayflower commemorative coin set, that were "cold enameled" (colorized) on one side. Here's one of them. The colorized side has undergone a pigmented epoxy resin treatment, that makes it look like hard enamel and gives it a dome shape. The Mayflower tokens come encapsulated and - guess what - I see bubbles on every one of them! Because I can open these capsules, I realized it's not moisture that's causing it. That gave me some hope for my ANACS slabs and so I contacted ANACS on Facebook Messenger, included photos, and asked them about the cause(s). They confirmed that it's not moisture but a "contact reaction" (their words) between the slab acrylic and the material of the inner "donut ring." That was a relief for me because I've always assumed they were moisture related. So, in case you have the same issues and didn't already know, here you go!
Those slabs Are not air tight thats just happens because over time air e.t.c can get in because it wasn't a tight seal in that area.
Hopefully, it's not detrimental (I hope!) ANACS said it was a "contact reaction" between the two surfaces.
So the phenomenon is a chemical reaction that is producing a reactant? What does ANACS say about long-term exposure of the coin to that reaction product?
I'm no expert and I'm not sure how to say this but I'll try: I think it's just a "visual thing" between two materials while they're in contact. In my Mayflower coin capsule example, the "bubbles" are there and then disappear without a trace once the capsule is removed and no longer in contact with the epoxy resin. I assume the 2009 Lincoln bicentennial cents have been in their holder for more than a decade. So far so good. Keep my fingers crossed.
This is all too complicated. Imagine pressing your palm against a window and then looking at it from the other side. It just looks smooshed together. The rubber surround is not entirely flat, and it makes contact with the inside of the holder. It’s just where they make contact, is all. It is the opposite of a bubble. A bubble would assume it touches everywhere but in some places has an air gap. It reality it has an air gap everywhere but touches in a few places.
Got it. No chemical reaction. I've seen this "contact reaction" elsewhere between materials but it won't come to mind right now.
I think you hit the nail on the head. I like your explanation the best. At least it's not moisture or anything detrimental to the coin. Whew!
Could be, but it seemed like on my ANACS slabs I got a really strong impression of air bubbles, rather than contact points surrounded by air. Next time I have them out of the SDB I'll look again.
Yeah, acrylic and rubber (silicone I assume) don't exactly mix, sort of like the sealant used for a fish tank, where the two make contact there's this funky "wet look" even with clear silicone sealant when it's viewed through the acrylic. it's got something to do with the softness of the silicone and the hardness of the acrylic and then I think likely air pressure (barometric?) making it appear bigger or smaller as the materials flex and contract.there's something sciency going on there, and apparently ANACS has fielded that question more than once over the years. the palm against the window is a good example actually. try as you might, you won't get your entire hand completely flat and in contact with the glass all at once, there will be spots that don't make contact. Of the areas you do make contact, it will mush or distort a little bit from the pressure of pressing against the glass.
You will also see them the same thing on NGC slabs where the insert makes contact with the outer shell. Not moisture just contact between the soft material and the hard rigid material. You will sometimes see it on PCGS slabs that used the soft "rubber" rings around smaller coins in large opening shells. If the ring makes contact with the shell you see the same thing.
