Over the weekend DW had me working on several projects around the house and I ran across some OmniGlow Cyalume lightsticks that had been in a box in the closet for several years. Expiration date was 5/01.

Seven years past the expiration date, the original foil wrapper was still sealed. These had been stored in a closet (dark, fairly constant temperature, no rough handling). The foil wrap seemed to open at the seams a little easier than I remember on a new package. Maybe the glue wasn't quite as good as new? When I broke the stick, and gave it a shake, it worked like a new one. Good bright light. I did not have a new one to compare intensity of light. After two hours, it was not as bright, but still bright enough to read fine print. (This was a 30-minute hi-intensity yellow stick.)

Anyway, my highly unscientific test conducted in a dark bathroom on Saturday night revealed that a Cyalume light stick can still be usable seven years after the expiration date.

I would still pay attention to expiration dates for critical use, like stocking a life raft, for example. But, if someone offered me some expired sticks, I would grab them and use them up on camping trips.

This is good to know. I get them free from work and have hundreds of the things lying around. I used to give them out with candy on Halloween to the kids get rid of them.

Although I consider them more of a bonus light source than a real emergency one, At least I know they will work.

What do you do to get free light sticks? Do you get tyem from the military?

I've conducted similar tests and found that the older sticks are substantially dimmer than the fresh ones. It seems that they just gradually fade over time. Keeping them air tight definitely seems to help.

Craig.

I don't think I'd be too worried about a foil sealed light stick, even 7 yrs. I think the expiration date is baloney - as long as the chemicals don't contact each other or if they are stored in excessive heat conditions they should be fine.

I think it was in Robert Nielsen's video that he talked about the useful life span of these things.

Typically discount chem-lights use chemicals refined to a lesser standard of purity and these degrade much more quickly and less gracefully than higher quality light sticks. Also all of these units degrade more quickly in warmer temperatures and have much shorter storage lives if the foil wrapper, intended to keep oxygen out, is punctured.

wow! those light sticks are older than me!!!!

Most of my clothes are older than you!!!

I have inspired The Duh !!!!!!

My life is complete.

I think heat and light are the foes for light sticks. I think mine held up so well due to the unintentional good storage conditions (sealed foil wrapper, no light, room temperature). I would be interested in how they would fair riding around the the trunk of my car. Think I will give it a try. Get back with you in seven years.

I think your right. Also Omniglow, as I understand it, supplies the majority of the USGI sticks and they are made to a very exacting standard. Quality units stored under favorable conditions last longer.

It would be interesting to find out what the Omniglow people and USGI standards say about their minimum expected longevity and recommended storage parameters.