... very interesting!

I found the Air-Tites homepage, from which you can purchase air-tites (ringed and direct fit) directly:

http://www.air-tites.com/index.html

The rings are made of cross-linked polyethylene (trade name "Volara", manufactured by Voltek, Inc.), which the Air-Tite site describes as "inert".

Independent of the Air-Tite site, I found that the American National Standards Institute (ANSI) and the National Information Standards Organization (NISO) did a study (which was approved on March 2, 2001) entitled:

"Environmental Conditions for Exhibiting Library and Archival Materials".

This study considered environmental factors affecting the storage and display of rare/valuable library and archival materials, including light, relative humidity, temperature, pollutants and storage/display materials. It even discusses encapsulation!!

For those who are interested in seeing the complete study, it is at:

http://www.niso.org/standards/resources/Z39-79-2001.pdf

To get to the point, however , the study has an Appendix B which lists materials which are considered "generally safe" (B-1) and "generally unsafe" (B-2) for use in displaying archival materials. Keeping in mind that the study does not address long-term, permanent storage (for which it recommends "conservator" review), the "safe" materials include:

"Cross-linked polyethylene (e.g., Plastazote; Volara)"

... as well as several other foams and plastics.

The "unsafe" materials include, among others, PVC products (and most everything with chlorine or chloride components).

Also found a site maintained by the Fairfax Va County Park Authority, which lists cross-linked polyethylene as safe to use for "Curatorial Care of Archeological Objects". See Appendix 13 of their manual at:

http://www.fairfaxcounty.gov/parks/parkpolicy/parkpolicyframe.htm

Finally, for an interesting discussion of Volara, see this site:

http://www.voltek.com/prspacecamera.htm

... which describes the use of Volara in Princeton University's deep space camera project. A mechanical engineer named Michael Carr used Volara to protect the camera and said:

"Volara is an excellent thermal insulator, very clean and flexible even at cryogenic temperatures. We actually dipped the material in liquid nitrogen to see what would happen. Where most materials instantly become brittle, the crosslinked foam maintained its flexibility. In addition to remaining flexible to -200°C or -320° C, the insulation properties of the foam inhibit up to 99% of the condensation typically generated under these conditions."

I'm not sure I understand all that , but it sounds pretty good!!

None of this, of course, directly addresses the use of this stuff to store chips, but it does sound like it is probably safe, even for relatively long term storage. In any event, it puts my mind at ease regarding the use of the ringed air-tites for my chips.

----- jim o\-S