If a 25-year-old Speedmaster with a tritium dial glows brightly after being exposed to a light source, does that mean the hands and markers have been painted with some kind of luminova? Please correct me if I’m wrong, but I thought tritium is self-illuminating, which only lasts for a few decades, and is not charged at all by light.

 

I believe that tritium is the "power source" and the compound that emits light is a phosphor. After the tritium has aged sufficiently (i.e. experienced significant radioactive decay), it doesn't power the phosphor enough to cause it to glow continuously. However, I believe that some phosphors may glow briefly after being charged by a strong light source. If it were luminova, it would probably glow for quite a while after being exposed to light. I think that others on the forum will probably be able to give you detailed guidelines about how long these phosphors will glow after being charged by visible or UV light.

 

It depends how long. By 25 years, I'd expect it to charge for a few seconds and quickly lose a large % of the light it first emitted and only faintly glow for a little while longer. Like maybe for 60 more seconds.

 

The word "brightly" is subjective. How long it glows is less subjective. Old tritium exposed to a really bright light in a really dark closet can glow "brightly" at first, but will fade significantly within a minute. After 5 minutes, the glow will be pretty much gone. A luminova dial will be easily readable an hour later---sometimes overnight.

 

The phosphor also makes the lume look whiter when illuminated with sunlight. The UV activates the phosphor and it glows white.

 

Great question! I was wondering the same thing with my 3590.50 that I recently got. Thanks for the answers everyone!

 

Generally tritium is useless after 30 seconds

 

and to add for correctness: it is not phosphor but zinc sulfide which is activated by tritium

 

Umm it is a phosphor in that it is a substance which glows irrespective of chemical makeup. It isn’t Phosphorus, but Zinc Sulphide is still a phosphor, As is Strontium Aluminate.

https://en.m.wikipedia.org/wiki/Phosphor

 

See a similar thread here :

https://omegaforums.net/threads/145-012-67-clean-original-or-good-relume.76979/

Cheers.

 

It does fade quickly in the first minute and is almost completely gone after about six or seven minutes.

 

I’m not really looking for good lume. I have dive watches for that. I just like the aged look and warm patina that tritium develops over the years.

 

It’s how you tell which it is. As someone’s unsure how to tell.

 

Sorry, I misunderstood. I’m still wondering though if a cheap luminova would lose its lume at the same rate because I have a very inexpensive beater watch that behaves the same way.

 

No it will glow at a useable level for a few minutes at a minimum.

 

Agree.

 

Here's some testing I did on my own watch a couple months ago. The consensus was that I have a tritium chrono hand and luminova hour and minute hands. In daylight all three look pretty much identical. I'm kind of surprised that luminova would be as bad as this shows - the glow is pretty much entirely gone after 10 minutes.

https://omegaforums.net/threads/how...nds-are-later-tritium-or-superluminova.72181/

 

Here's my Speedy which got me wondering the same thing. I didn't expect the hour markers to glow but they do glow a little after going under a flashlight and they fade faster than the hands do. I was just surprised that the hour markers glowed at all.

 

I like your demonstration so much that I did the same. The first photo was taken after shining a UV light on the dial. The second photo was taken 30 seconds later. The third photo was after a minute. Based on this, the hands and markers appear to be tritium since they diminish quickly and evenly. I’m just surprised there are no signs of aging other than a slight yellowing in color.

 

Here it is in bright sunlight: