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RealRockets

Finally! My profession and hobby over lap! The reason that it doesn't glow on its own anymore is due the fact that most of the tritium has decayed away. That said, the tritium isn't actually what was glowing, it is what was used to cause a different material to glow. The electrons produced from 3H beta decay excited a phosphorescent material which then glowed. This is similar to how cathode ray tubes work. When you shine a light on the phosphorescent material, photons do the same thing as the electrons did, but once you remove the light source the phosphor will eventually return to the ground state and stop emitting light. The phosphor isn't radioactive so it doesn't decay away. There is no need to be concerned about dust from outside. Try not to inhale or ingest (ie wash your hands or handle with gloves) if you open it up. This is more because phosphorescent materials aren't that healthy. There probably still is some 3H, and while I don't recommend licking beta emitters, given the quantities here it isn't a huge risk. Id suggest a service to replace the crystal, service the movement, and clean any loose dust. Just to be considerate give the watch maker a heads up it was 3H lume. **edit** for clarity and to add, it is 100% not radium lume. That was phased out decades earlier. It is also probably not (super)luminova which was phased in during the 90s-00s and does not contain radioactive materials. That would likely still glow on its own.


SomeYotedThing

Thanks for the info! I was mainly concerned about the outside dust possibly being radioactive from being near the watch for so long, but seems like thats not the case. I appreciate the clarification, thanks!


RealRockets

You are right, there's not enough activity, and really not the right kind of radiation, to activate anything else even if it were brand new 3H lume.


mks113

I had a tritium lit LCD watch in 1979. Note that the tritium doesn't actually glow, it provides the energy source to cause phosphors to glow. It is typically contained in a small flat liquid capsule behind an LCD. It is similarly used on some Exit signs. The phosphor can be energized by radioactivity or by light, so yours is doing the expected behaviour regardless of it being tritium or not. In 1979 mine had a trefoil on the back stating the energy of the source. It was incredibly low. If yours is from the late 1990s (antique!?? I feel old.) it should be appropriately labelled.


pichael288

With tritium the gas inside is slightly radioactive (not gonna hurt you) and the inside of the glass is coated with phosphor that glows when struck by the decaying tritium.


233C

> It doesn't glow in the dark on its own anymore, it does get very bright when I put a flashlight up to it but only lasts a couple minutes. It's not tritium. If it were, shining anything at it wouldn' have any effect on its brilliance. Even assuming it were tritium, there would be very little risk as tritium is by far the least dangerous radionuclide. Radium would be a whole different matter.


StoneCypher

> It's not tritium. > If it were, shining anything at it wouldn' have any effect on its brilliance. It's a phosphor coated glass. The tritium provides energy hits to the phosphorus, causing the glow. Other energy hits also work. This is like concluding that a CRT television doesn't have an electron gun because electrons aren't colorful.


SomeYotedThing

Would radium do anything if I shine a light to it?


StoneCypher

This person is badly confused. The watch works the same way a CRT television does. There's phosphorus on the glass, and the tritium is a power source. The tritium emits beta radiation, which hits the phosphorus. The phosphorus then glows.


233C

nope, like tritium, the brilliance is independent of any external light source; unlike regular [phosphorescent](https://en.wikipedia.org/wiki/Phosphorescence) materials which need to be externaly excited before releasing teh stored energy in the form of visible light.


ppitm

Radium paint loses its visible fluorescence over time but will react strongly to a UV light.


StoneCypher

1. Tritium is an isotope of hydrogen. Hydrogen is *stupidly* difficult to contain. You can't even keep it in a steel or glass flask, because it'll leak right through the walls. That crack basically means all the hydrogen has leaked out. 2. Even if it hadn't leaked out, it has a half life of about 12.4 years, so if it's from (let's say) 1996, 7/8 of the gas would have decayed off by now 3. No, you shouldn't be concerned about tritium. You've been breathing radon all your life - everyone does - and we got antsy enough about that to stop using it in consumer products. Tritium emits a single beta (read: can't even pass the skin) and then isn't tritium anymore. Generally speaking, the only way it's typically dangerous is when inhaled in large volumes. Incidentally, large volumes basically don't exist, because the way it's made in nature is cosmic ray hits on the atmosphere, which are just a few particles at a time, and there's no known concentrating mechanism other than nerds 4. The amount of tritium in that watch was tiny. You could have eaten that thing, and you'd still take on more tritium walking around in a movie theater, from all those leaky exit signs. 5. You have never seen a lawyer commercial about the cancer people got from exit signs. Any actual risk shows up on `1-800-ambu-lance-chaser`. This is why you know the word "mesothelioma." 6. You're at substantially more risk from a dozen seemingly innocuous things in your home. 7. You get more radiation breathing five seconds of car exhaust.


Bigjoemonger

>2. Even if it hadn't leaked out, it has a half life of about 12.4 years, so if it's from (let's say) 1996, 7/8 of the gas would have decayed off by now Might want to check your math. 2022 - 1996 = 26 years 26 / 12.4 = 2.1 half-lives 1 half-life is 50% remaining 2 half-lives is 25% remaining


StoneCypher

Okay, I was off by a half-life. Not a huge issue in the greater scheme of things


Mommytofourkids

Also I couldn’t tell if it’s broken or not because all the lights were on in the gym, but from the outside I didn’t see any broken plastic? I took a pic of it if you want I can email to u? Not sure how to send pics on reddit


StoneCypher

please never send me any pictures of anything, you ridiculous person i am not a doctor and i have no interest in photos of perfectly safe things that you've decided to be afraid of it really seems like nobody in your life is successfully communicating to you how absurd your level of fear is. you wouldn't make a good movie character because nobody would believe a real human being could be this terrified of literally nothing. you're the kind of person that i give photos of apples with the chemical names of the apple bits inside, and ask which chemicals you're terrified of. please grow up. this group is for `fans of nuclear power`. this is not the first time i've seen you in here explaining how terrifying monoxygen hydranoic acid is.


Mommytofourkids

Do all tritium exit signs leak tritium even if not visibly broken? Today my 6 year old was at bball practice and was leaning directly on a tritium exit sign(had the radiation warning on it), I didn’t see til later that it was tritium. She touched it and was sitting/leaning on it for around 10 minutes, I’m worried it was leaking and she inhaled and absorbed some tritium into her skin, also that it contaminated her clothes etc. please help if anyone knows any info?? I’m worried sick for her.


StoneCypher

the general idea here is you're not supposed to be afraid because nobody in history has ever been hurt by an exit sign the reason i deferred to that example was because i thought nobody on earth could be afraid of an exit sign if you're "worried sick" because someone leaned on a sign for ten minutes and nothing happened, ***very seriously consider getting a therapist***   > please help if anyone knows any info?? Stop asking for information on the internet. Nobody here knows jack shit, and you're asking other stupid people like you to give you a list of everything they're afraid of, so you can be afraid like them. Be a regular adult. Ask a doctor, so that when they laugh at you, you can learn that this level of fear isn't normal or healthy.   > I didn’t see til later that it was tritium. There's tritium in the atmosphere. No human being has ever spent a single second of their lives not breathing it. Stop being afraid of the names of things. I get the impression that when people tell you "stop being afraid, this is silly," you lash out for your fears "not being respected." Everyone's spent way too much time coddling you. Stop manufacturing things to be afraid of. This will never help anyone, and this ***will*** harm your child.