I have seen a few threads about illumnation recently and some have extolled the virtues of tritium. There is no question, in a new watch with tritium, the consistency of the brightness at any time, even when the watch has not been exposed to light for a significant time, is outstanding. The discussion gets a bit muddied when one talks about watches that have aged for many years. Given that I have some aged tritium watches, some aged superluminova watches and some new superluminova watches, I thought I would try a bit of a scientific test to see what works.

This test consists of two parts. The first part was wearing each watch all day in varying light and then sleeping with it on my wrist and noting the state of the illumination when I awoke. The second part was to give all watches equal illumination – about 3 hours in a brightly lit room, then put them in a darkroom with all lights off and take pictures at the start, then at intervals of two hours. There was no need to go beyond the two hour mark to compare the tritium to the superluminova.

The watches in this test are:



From the top to bottom, then left to right with (purchase year):
Top Row - Tag Heuer Formula 1 Calibre 16 (2015)
Middle Row - Rolex Submariner (2000), Tag Heuer 2000 (2000), GV2 2008
Bottom Row – Omega Seamaster (1948), Tissot Ballade III (2013), Baume & Mercier Capeland (2000), Breitling Transocean Day & Date (2013).

The Omega and Tag 2000 have tritium. The rest, except for the Tissot have superluminova. The Tissot is not self-illuminated.

Sleep Testing:
The watches that had adequate illumination to allow for dark-adjusted eyes to read them all night were the Rolex, Tag F1, Baume & Breitling.

The Tag 2000 and Seamaster had marginal levels of ilumniation at the start of the evening, but in the morning were not illuminated enough to tell the time. The Omega was not lit at all.

The GV2 has useless illumination. Only the ends of the hands have superluminova and only in small amounts. While the hands were visible early on, there is no reference point and you cannot tell which is the hour hand and which is the minute hand.

The Tissot has no internal illumination and, therefore, I did not sleep test it.

Illumination Testing:

These photos were both shot at: ISO=400, f=2.8 & shutter=13 seconds.

As you can see in the shot below, at the start of the test, all watches were visible. The superluminova watches were brighter than the tritium watches except that the bezel dot on the Tag 2000 was much brighter than the dial leaving one to wonder if the bezel was a superluminova application to a tritium face watch – it was in the transition period.



In the photo after two hours, the superluminova watches, with the exception of the GV2, were still legible, but the tritium watches were not, except for the bezel marker on the Tag 2000.



Summary:

I tested 2 tritium watches that were 67 & 15 years old and 5 superluminova watches, 2 of which are 15 years old, one is 7 years old, one is 2 years old and 1 is a 2015 model. My results were as follows:


  • Both tritium watches failed in the mission of retaining enough illumination be read by night-adjusted eyes at the end of a night’s sleep.
  • 80% of the superluminova wathches passed the test of remaining legible through the night.
  • The superluminova watch that failed the test has a miniscule amount of superluminova material to begin with and even when it is llluminated, it fails the test due to a lack of reference points.
  • There were variations in the illumination of the superluminova watches. The two newer watches, Tag F1 & Breitling, were easiest to read at the end of an evening. This is due as much to design as materials. Both have adequate marker illumination and the hands are wide enough, especially the Tag F1, to really shine. The Baume hands remained well lit, but the markers are a bit small and, while visible, you have to look past the brighter hands to see them. The Rolex remained legible, but, while the markers were bright, the hands became a bit ghost like toward the end of the evening. They were bright enough to read, but, due to the thin hands, they were somewhat harder to make out than the other brands’ hands.
  • While I am unaware of any 15+ year old tritium vial watches, I have several weapons with tritium night sights on them. Those sights are tritium vial construction and in the older sights, visibility becomes a problem just like the tritium paint on my watches.


Conclusion:

If you are buying a watch to keep for years and are desirous of having the ability to read the watch in the dark after a bit of time, superluminova is a better material than tritum.