Tritium Lume

padders

With Tritium, the lume effect fails after about 20 years and the colour often changes, it goes darker but peeling off is actually pretty rare. Tritium was first used around 1962-3 and there are plenty of examples of that age that haven't behaved like you suggest, the vast majority in fact. Those that have may well have been subject to external forces such as moisture, overexposure to sun, poor maintenance etc.

padders

SL/Luminova (same thing) Luminova

padders

With Tritium, the lume effect fails after about 20 years and the colour often changes, it goes darker but peeling off is actually pretty rare. Tritium was first used around 1962-3 and there are plenty of examples of that age that haven't behaved like you suggest, the vast majority in fact. Those that have may well have been subject to external forces such as moisture, overexposure to sun, poor maintenance etc.

M'Bob

It’s odd: I have two 105.012, and one 145.012. All sourced 20+ years ago, all from different places. And none of them retain their original lume. The same goes for pictures I have searched for regarding the same watches. Yet, Speedmaster references both before and after seem to more often retain their lume. Of course, I could have just bumped into a bunch of outliers, so this is just my observation, not science.

padders

Bear in mind SL is still used today and has only been around for about 25 years. Tritium hasn't been used since the 1990s so the tritium dials will be 25-60 years old, the SL dials 0-25 years old. SL certainly degrades much less in every respect than radium or tritium lume but they are also necessarily younger than either of those other radioactive lume materials.

Heisen0erg

I am not a watchmaker but I do know a thing or two about radiation:

The reason for the peeling/cracking might stem from the fact that tritium is radioactive. I assume that the they don't just use plain tritium but they do mix it with other compounds like glue in order to form the small dots you usually find on older Omegas. Since tritium always fires some electrons around itself this affects the other compound/surroundings as well since the glue molecules are getting shot by these electrons. This weakens the glue. Now if you live in a humid area this will further burden the structural integrity of the whole lume resulting in flaking sooner than later.

Mouse_at_Large

I've found this to be an interesting and informative paper on the various forms of radioluminescence https://www.orau.org/ptp/collection/radioluminescent/radioluminescentinfo.htm

Should you be interested in how to get tritium (a gas) to a state where it can be used in a luminescent paint, this patent may be of interest https://patents.google.com/patent/US3033797A/en

Mouse_at_Large

I've found this to be an interesting and informative paper on the various forms of radioluminescence https://www.orau.org/ptp/collection/radioluminescent/radioluminescentinfo.htm

Should you be interested in how to get tritium (a gas) to a state where it can be used in a luminescent paint, this patent may be of interest https://patents.google.com/patent/US3033797A/en

Marsimaxam

Great explanations all.
The color changing or patina of the tritium is exactly what I like about tritium and no two age exactly alike. Some age to dark rich pumpkin patina and others to a more creamy appearance and all the shades in between.

So many things affect the way tritium will change color... exposure to light, age, moisture, humidity and temperature... but it’s beautiful.
I believe somebody asked for pictures ...two are radium dials

Marsimaxam

Great explanations all.
The color changing or patina of the tritium is exactly what I like about tritium and no two age exactly alike. Some age to dark rich pumpkin patina and others to a more creamy appearance and all the shades in between.

So many things affect the way tritium will change color... exposure to light, age, moisture, humidity and temperature... but it’s beautiful.
I believe somebody asked for pictures ...two are radium dials

u35rm8

Those are some brilliant vintage examples you have amassed there.

padders

With Tritium, the lume effect fails after about 20 years and the colour often changes, it goes darker but powdering or peeling off is actually pretty rare. Tritium was first used around 1962-3 and there are plenty of examples of that age that haven't behaved like you suggest, the vast majority in fact. Those that have may well have been subject to external forces such as moisture, overexposure to sun, poor maintenance etc.