Pete -

http://antiques.about.com/hobbies/antiques/c/ht/00/07/How_Properly_Store_Old0962933988.htm

http://www.kodak.com/US/en/corp/membersGallery/archiving/pagesToAvoid.shtml

I checked back through the ChipBoard archives to find the above links that I posted to a message regarding a thread on what may be the same type of problem http://www.thechipboard.com/cgi-bin/tcbarc05/tcbarc05.pl?read=132388. Of course these links refer to the effects of PVC on photos but they may shed a little light and be relevant to what is happening here. I have noticed on most of my BJ chips that the inserts do seem to be paper. That could make these chips even more vulnerable to damage. As a photographer I am familiar with the problems that PVC can cause. As I mentioned in the previous thread, many of the pages that are being used are designed for use with coins and may not be of such concern with items that durable. However, with plastic and clay chips the item being protected may not be as safe in that the chemicles in the pages may be able to discolor disolve or in many other ways damage chips. Also notice that with your best coins, Uncirculated and Proofs, they are encapsulated in hard plastic cases. It may be that The US Mint and other dealers know that soft plastic pages may not be safe for high quality coins and that they may harm the fine finish on the coins. The hard capsules are more durable and definately will provide a higher degree of protection.

Another possibility other than PVC might be Moisture. In Las Vegas you may not have the humidity problems that we have here in Illinois but I also noticed that sometimes moisture can collect in the plastic pages and damage the items being stored.

I have been using AirTites for long term storage. Once the chip is in the holder and it is sealed moisture and air do not seem to get inside. One thing that I did notice the other day though. I had washed some slot tokens and was placing them in plastic capsules. I noticed that the heat from the warm water was foging the inside of the capsule and getting trapped inside. Make sure the contents inside are thouroughly dry before you seal them in. From what I was reading recently about AirTites, I think on JPsCorner.com, they are supposed to be free of PVC. Another benefit of sealing in the AirTites is that air does not get in either. I have some Silver Strikes that I got on my first trip to LV. 6 years ago I got a token from RIO that no longer has the gold ring on the edge. It is now brown. The original capsules that SSs come in has a small slot in the edge. That allows air to get in. I have now taken all of my SSs and put them in AirTites. The gold color is holding nicely.