Yesterday I was handling one of my vintage watches and I could see there still was some lume on the hands and the time markers.
Now I am just curious about how the lume behave in different environments and an "experiment" starting to grow in my mind:
If I bought two identical watches in 1970, lume on the hands and on the time markers and put one of them in a dark closet until today. The other one I put on my wrist in 1970 and used it every day until now. What would be the difference in how the lume material react or behaved on the two watches? Any ideas?
regards
Terje
I think the original lume that aged (Tritium) reacts both to light and the radiation in the paint. I would therefore expect the daylight watch to have aged more (less reactive) than the one only exposed to its own radiation. Both would have aged though.
If they're tritium, the one kept in the dark would likely be darker (eggshell/yellow/tan) compared to the one that's been exposed to the light regularly.
I doubt after 47 years either would still glow.
I don't think they'll be much difference.
The one exposed to light might age (darken) due to exposure to sunlight (as dials might) but the luminosity shouldn't be very different.
No. It's the other way round with tritium.
Dark darkens, light lightens.
Luminiosity naturally degrades in both over time.
The tritium dialled Tudor sub I traded with Simonsays a few years ago spent around 29 of its 32 years in the dark. The plots had barely faded and still glowed well in the dark after exposure to sunlight - though the glow didn't last very long (I can't remember how long, but probably not even a glimmer after more than an hour, even when viewed in pitch black)
ATB
Jon
Sounds like it is wizardry to me...
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Tritium lume is a 2 ingredient thing (well, more than that, but 2 active ones).
One is the tritium as a radiation source. The tritium source has no glow itself, it is there to excite the emitter, the phosphorescent ingredient, to make that glow.
The second ingredient is the phosporescent material.
So in modern tritium tubes, the tube is filled with a concentration of gaseous tritium, and the inside of the glass itself is coated with phosphorescent material, and it glows as the tritium's radiation excites it.
The glow is depedent on the excitation. More excitation, more glow.
And tritium's ability to excite suffers with time, a half life of 12 years, so only 1/16 of the radiation after 48 years. Not much left, in other words.
But, the phosphorescent ingredient can still get excited, and strong light does exactly that, making it glow, if only for a short time.
So, over time, the trit activity drops, and the glow also diminishes.
The general laws of hysteresis loss would suggest that the more the lume is charged and used, the less it will glow over time. Worn watch = less glow
And also it is likely the worn watch will be warmer than the stored watch - and decay is thermally accelerated. Worn watch = less glow
As to what it looks like, it makes sense to me that the light exposed watch is more bleached out than the safe-stored one. But that is another set of mechanisms which depend on stuff I have no idea of, and is likely to depend just as much on the binder medium (theird ingredient) as anything else.
So I think the worn watch would look paler and glow less.
D
Can a tritium dial/hands be restored ? (Lume only, the dial itself is perfect)
'Against stupidity, the gods themselves struggle in vain' - Schiller.
Wizardry for sure. Along with noise cancelling earphones. Burn them!!!
Thank You all for very informative answers.Much appreciated
regards
Terje
I agree with Sweets, but just a note if clarification - the radioactive decay (half life) of tritium isn't affected by temperature, but the degradation of the luminous paint will be. I'd expect sunlight to have the same effect.
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