Are certified encapsulated coins really air tight?

busterwilson · September 14, 2005 8:36AM

HI- I Look at my coins all the time. I have many cerified encapsulated coins. But it seems to me that some of these are toning and or aquiring problems.
Do you think that air can still pass thru? Is this my imagination or defective capsules?
Is there any further steps to be taken to better preserve these coins? Right now, I have them in a safe with a dehumidifying agent located at the bottom of the safe.

Any do's or dont's appreciated.

MrSpud · September 14, 2005 8:38AM

Make sure it isn't one of those fireproof safes that are very humid inside. I had a friend who stored his coins in there and they were ruined.

The book Coin Chemistry says that slabs aren't airtight and the author did experiments gassing the slabs with hydrogen sulfide and showed that the coins could tone/tarnish right in the holder. This was with earlier holders, supposedly newer ones are somewhat better but still might not be airtight. The author suggested actually putting the slabs against your mouth and trying to suck air through the seal as a test.

There are intercept shield holders for slabs that are supposed to neutralize corrosive agents before they can attack the coins. A cheapy way to protect the coins would be to put the slabs into glass jars with airtight lids with some silica gel in the jar before placing the coins in your safe.