Dear OF.

During the last couple of years of interest in watches, I have of course wondered a couple of times about lume. Especially after having purchased my last two Rolex: a Submariner from 1985 and a GMT-Master II from 1993. The lume antivity (or what you should call it) of these was very inconsistent with their age and having read a couple of threads on various forums I decided to buy an UV-light. Particularly I was worried that my GMT had a repainted dial and hands and that the hands on my 1985 Sub was painted to match colour of the hour markers since nothing on my GMT lumed when exposed to even very bright light and only the hour markers on my Sub was luming when in bright light but not the hands.

I had also read this excellent thread here on OF: https://omegaforums.net/threads/tritium-lume-doesn’t-light-up-under-uv.81995/

So the UV-flashlight was bought and I was happy to find out that everything lighted up under the UV.

What is funny is the inconsistency in relation to age.

My 1993, GMT 16710 lights up under UV but the hands and hour markers only does for a second of two at the max and the shine is very faint. You have to be in a dark room with eyes adjusted to the light.

My 1985 Submariner lights up under UV but the hands shine only for a second max and very faint while the dial shines for 10-15 seconds before dying completely again.

My 1985 Speedmaster lights up similarly to the Sub from 1985 but the hands of the Speedmaster shines almost as long as the hour markers.

My 1963 Seamaster 30 lights up as well on the small hour markers but the shines lasts only half a second.

So what can you gather from my experience and all the threads you can read on the issue??

I don’t know other that it is very inconsistent. Some Rolex from the 1990’s seem to be almost completely dead and light up only for a second or two under UV as mine. I read about a guy with an Explorer from 1995 what did the same. Yet still both a Speedy and my Sub has hour markers that glow brightly under UV, even thought they are 8 years older, but with hands that die faster than the dial hour markers.

My guess is that the amount of radioactive materiale, the type of paint used, additives to the paint, how much UV light the watch was exposed to during its life and perhaps other condition as well caused this inconsistency with lume activity and age.

It certainly is strange. Anybody else have examined theirs with UV?

 

I made some comments about my limited experience with lume in this thread which may help:

https://omegaforums.net/threads/gallet-ep40-68-landed-chrono-hand-question.82418/#post-1068891

I have a small collection of vintage watches at this point, but what I have experienced concerning lume seems pretty consistent thus far to my way of thinking.

Most in here may agree that, in the case of vintage watches, the lume applied to the watch face and the lume applied to the hands each were applied by different entities or people and with some separation in time and there could be slight variations in the lume formula as well and therefore both daylight appearance and appearance under UV light may differ in depth of color or saturation and sometimes in hue as well. The fade time under UV light may also differ but not dramatically so.

I wouldn't worry too much about the differences of a few seconds one way or another unless significant such as would be the case when one discovers the dial may be original tritium whereas the hands were redone with color-matched Superluminova.

I recently purchased a 1962 1308 BaNCH Sherpa graph and the creamy color of the lume worried me because it was too good looking:



When I received the watch, I could not wait to hit it with some UV light:



The lume on the dial of this 1962 watch fades very rapidly in two or three seconds while the lume on the hands fades in 6 or 7 seconds.

Under similar conditions for my 1966 Mark III Sherpa Graph, the lume on the hands fades in about 5 seconds whereas the lume on the dial survives for about 9 seconds.

Is the above consistent with expectations or inconsistent?

To my way of thinking, this is darn near perfect.

FYI, the lume on my Gallet MC 12H circa 1968 last for maybe 15 seconds or more and the hands and dial fade nearly identically.

Hope this helps a little.

~ Joe

Edit: I was actually retesting at my desk while I was typing.

 

I have come to view the UV test with a grain of salt after reading many articles.

 

When you're using UV light, I wouldn't expect the lume to glow for more than a few seconds. That's normal. You're using UV light as a surrogate energy source, as opposed to the radiation from the tritium (which has died out due to its short half-life). The lume should really only glow as long as you are supplying it with light of the right wavelength (i.e. UV light). When you remove the energy source, the lume dies out. Tritium has a half-life of 12-13 years, but the luminescent material itself (e.g. zinc-sulfide) still works using an external energy source.

 

Whereas in the case of radium, radium's alpha particles destroy the lume over time due to high energy alpha particles. So even if the radium is still 100% radioactive (with a half-life in the 1000s of years), the lume no longer works because the zinc-sulfide matrix has been damaged by radiation. That being said, UV can still activate damaged radium lume (presumably because UV light supplies a lot more electrons that the alpha decay of radium, although I haven't exactly been able to figure this out completely).

 

Radium lume on my LeCoultre and my Tissot!

 

Not forgetting that most vintage watches the parts were made by various places

Hands and dial may have come from seperate suppliers

 

As to the issue of the hands and hour markers not glowing for the same duration, I wouldn't think that would be a major issue. Maybe it relates to the amount of matrix/fluorophore they applied to the hands vs the hour markers? As @Joe_A mentions, if there's a huge gap, then that may suggest Superluminova, since it's made to glow after the light source has been removed

 

I agree. What I was after in this particular case was if the original lume plots had been removed and “ordinary” paint applied. But that wasn’t the case luckily But I had to use the UV to determine that because the lume on my GMT didn’t react to bright white light, only UV.

 

I still find it strange with such variation between models of the same brand and within model lines. It seems there has been great differencens in the quality or content of the paints applied or external factors play an important role in the preservation of the luminous ability of the paints since many newer ones has a way lower intensity than some older ones. It should all be taken with a grain of salt I guess...

 

It’s not the radioactive substances that make the difference they just energize the lume before they have decayed past usefulness. When these where made they glowed all night and would still be glowing if placed into a drawer for 3 weeks.

The difference in timing after UV exposure is just due to the different formulation of luminous materials. That used to be energized by the decay of radioactive substances.

Different brands, different batches, different affects of ageing that changes the chemicals composition and lume qualities.

 

One would have expected some of the older ones to have stronger paints as it was slowly being phased out less tritium would have been used.

 

Very good point

 

Wouldn't expect the lume to react to "bright white light" regardless if it was tritium/radium. Only UV has the right wavelength to excite the lume, not regular visible light. The lume was originally activated by alpha particles emitted by the tritium/radium, and it just so happens that UV light has the same wavelength or energy characteristics to activate the lume.