Earlier this week, we brought you an historical perspective of the century-long journey to bring luminescence to the watch dial for easy night and underwater reading. As we mentioned at the close of that article: the favored materials used today for watches is Super-LumiNova (developed just about two decades ago in the early 1990s).
Super-LumiNova is non-radioactive and is a strontium aluminate substance created in a host of colors that enable the watch numerals, markers, hands and other dial accents to glow blue, green or even red-orange depending on the mixes used. Over the decades, the material has advanced thanks to a great deal of research and development, and the Super-LumiNova of the early 1990s has evolved into a new intensity that is at least double the strength of the early versions. Super-LumiNova can be as much as 10 times brighter than the previous zinc sulfide-based materials, and is applied in varying strengths.
After absorbing sufficient UV light, the phosphorescence glows in the dark for hours. The pigments, though, must be protected against contact with water or moisture, and so they are generally used only on dials (since they are protected by the crystal) and not on bezels. Super-LumiNova is the current market leader for luminous watch dials.
However, there are other materials on the market that some of the professional sports watch brands are using for dive and pilot watches. Top among them is a tritium-based device called "gaseous tritium light source" (GTLS), wherein the material is encapsulated inside tiny glass tubes. These tiny tubes are then placed together to offer a brightness that can be as much as 10 times brighter than applied Super-LumiNova.
MB-Microtec is a big developer and supplier of the tiny tubes system – offering GTLS radioactive luminescence locked inside hermetically sealed capsules. It should be noted that GTLS is forbidden in certain countries even though it is encapsulated in glass tubes because the material is, after all, radioactive.
Which is better? It may not be that one is better than another, but that, in fact, one may be longer lasting than another. For instance, it has been found that while Super-LumiNova begins to dim after about 20 minutes, a tritium capsule will not dim for about 15 to 20 years. Additionally, while Super-LumiNova needs to be exposed to a light source to regenerate its power, the capsules are permanently luminescent during their lifetime.
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