How long does the tritium in compass last?

[DaveH]

I see15 year old military compasses on ebay, I figure the tritium markers are pretty much non functioning by now?

 

[Bohica2u]

Hi Dave...........I think that the luminous material used in compasses (and some watches) are activated by light and stay "luminous" for a couple of hours. Of course, tritium will stay luminous based on its half-life. My Glock 19 just reached 10 years on its original tritium night sights and now they are very dim. My Silva Ranger is over 12 years old and the markers still activate when I give the compass a burst from a flashlight.

 

[MelancholyMutt]

tritium is not the same as light activated phosphorescent paint. The light activated stuff would pretty much last forever as long as the conditions are correct. Military compasses are not hermetically sealed and thus it's life depends upon the atmosphere.

As for Tritium, it's half life is 12.3 years... meaning, in 12.3 years, it's going to be half as bright as original. Then, in another 12.3 years, it's going to be half of that half, or 1/4 of the original...then, in another12.3 years, it's going to be 1/8. I think by the time it's about 1/4 the original, it's pretty much useless except in dire emergencies. Now, although you can get a manufacture date on the tool thats got the tritium, you don't know how long it's been since the tritium was manufactured. Thus, I'd say you can reasonably expect about 20 to 25 years of service.

 

[DaveH]

Thanks,

There are some on ebay that are sometimes 20 years old, and the seller always
says "Great Tritium". I pretty much figure they where full of it.