The Swatch group has exclusively used this material on all of their watches since 1997. The company describes the luminous properties as a “light battery.” Compared to radium, the product is an inferior “glow in the dark” source: the luminosity degrades 90% after one hour. But, it will still glow faintly for about 6 hours and can still be seen in the dark, although not “glowing” like the earlier radium material. Still, since there are no apparent health hazards with the Super-LumiNova, it is much preferred in modern watch products. A similar material is used on all Seiko watches, going under the trade name: LumiBrite.

By the 1950’s and 1960’s, with the realization that radium was no longer a viable material to use on watch dials, the industry began using alternate materials to achieve the desired results. Non-radioactive phosphorous compounds were tried, but the results weren’t optimal. It was the introduction of Tritium which proved to be a good substitute for radium. Tritium is a short range radioactive emitter, so it didn’t have the extremely hazardous properties as that of radium, and proved to be a relatively safe material from the harmful effects of inhalation, ingestion or skin absorption. Tritium has a half life of about 12 years, and needs to be repainted on the dials and hands at regular intervals to assure the watch keeps the “glow in the dark” look.

 Since the early 1990’s, the industry has begun to phase out the use of tritium on dials. Even though the risk as compared to radium is slight, tritium is still radioactive, and there have been reports that wearing a watch with tritium on the dial for several days may allow the tritium to diffuse through certain watch cases and absorb into the skin. Several countries have announced strict controls on the importing of radioactive materials, and this has had a huge impact on the watch industry.

It must be noted that not all countries have adapted the restrictions on radium and tritium. During the Gulf War it was surprising to find that tanks captured from the Iraqi Military had radium on its various gauges.

When all is said and done, it seems that the utilization of luminous substances on watches was a positive leap forward. When it was first introduced, electric street lighting was mainly prevalent only in cities, so this was a nice addition to any timepiece when you were out and about. At home, I suppose it was a great way to tell time during the night. But today, with everything in our society constantly being lit up like a Christmas tree, I find that the luminous on a watch serves as a “value added,” and not really that functional, unless you really need to see the time on your watch during the night.  A mediocre watch design can be made much more attractive with an interesting colored luminous dial and hands. I think it enters into the realm of the “Cool Factor… as in, “Hey guys, look at how cool this (awesome, bad, killer, etc.) dial lights up when you hold your arm into the dark closet.”

Postscript: After we published the article I got several emails and follow up posts to the article telling me that I was wrong in my conclusions, and that a good percentage of watch wearers actually use the luminant for telling time at night, or in dark environments. I  was under the impression from my general observations, that most everybody learned the time from their cell phones, since all I see around me are people with  their eyes glued to the cell phone screen.  I guess I should never underestimate  the time proven “Old School” methods of watch enthusiasts.

We recently answered the question, “What Color Luminant Is The Brightest And What Is The Best Lume?” Take a look…