Radium, Tritium and Super-LumiNova: usefulness, operation and their history

When we are interested in the world of watchmaking, we frequently hear the term “Super-LumiNova” and more rarely the words “Radium” or even “Tritium”. These rather technical terms ultimately refer to the luminescent material used on the dial of your watch. Each of these materials has its advantages, disadvantages and more or less undesirable effects.

History and technical advances

Today, at night, we are surrounded by light and can produce it instantly with our cell phone. The dark night has therefore become an obsolete expression. At the time, however, the night was really dark and it became difficult to read the time on your watch. It is to meet this need that Radium has been used in watches for its luminescent capabilities. 

Discovered by Marie Curie in 1898, it didn't take long for an innovative watchmaker to utilize its properties. The indexes and watch hands, once covered with this material, shine constantly thanks to the radioactivity emitted. Exploited for decades, it was in 1963 that the use of Radium was stopped, considered far too dangerous for health. The employees responsible for depositing the Radium on the needles were mainly women. Called “radium girls”, they were victims of the adverse effects of radioactivity and many died.

It was following the ban on the use of Radium that Tritium appeared in the world of watchmaking. In fact, it is considered less radioactive and therefore less dangerous. However, after several years of use, it was quickly banned as potentially dangerous. 

Subsequently, in the 1990s, LumiNova appeared. Invented by the Japanese company Nemoto, this phosphorescent pigment has the enormous advantage of not emitting radioactivity. LumiNova is still used in some watches but the most widely used phosphorescent material today is Super-LumiNova or SLN. 

Super LumiNova was invented in 2007 and is now found in most quartz and mechanical watches.

Technical properties

Each luminescent component has advantages and disadvantages, and even undesirable effects. Better understanding their functioning and characteristics is important for any enthusiast but also for a first purchase, in order to know what to expect. 

Radium

The advantage of radium lies in its ability to produce constant light radiation with high intensity. Its disadvantage or at least its undesirable effects are the constant radioactivity that it emits.

In order to easily recognize Radium, you can finally take out your old Geiger counter to measure its radio activity (just kidding). On this type of dial, you will distinguish Radium by its brown/brown color but also by its constant luminescence. Additionally, if your watch was produced before 1963... Chances are it has Radium indexes and hands.

Tritium

Also a radioactive component but to a lesser extent, it allows it to shine constantly for around ten years. The disadvantage is its fairly limited lifespan and of course its slightly radioactive side. 

To recognize Tritium you can check its radiation, it should be quite weak but constant without needing to be charged. To make it simpler, you will also find the inscription “T” on the bottom of the dial, generally following the place of manufacture. Here we can read “T Swiss Made T” at 18 p.m. which means that the material used is indeed Tritium.

Luminova & Super-LumiNova

Finally, let's talk a little about the latest, the new luminescent components that are LumiNova and Super-LumiNova (SLN). The main advantage is that this time, they do not represent any danger to health. Another definite advantage is also the lifespan of this material. Indeed the lifespan of the SLN is “unlimited” but the intensity decreases after around ten years all the same. 

The disadvantage is directly linked to its advantage: its luminescence. Unlike its ancestors, it is non-radioactive and therefore cannot afford to glow constantly. It is now necessary to “charge” this material with UV so that it releases the accumulated energy. The greater the charge, the higher the luminescence period will be. 

The lighting duration of the LumiNova is approximately 5 hours compared to 15 hours for the Super-LumiNova.

Recognizing Super-LumiNova is easy, you simply have to leave your watch in the dark, if it no longer shines after a few days, it's SLN! Additionally, if your watch is relatively new then it probably has Super-LumiNova indexes and hands.

Particles and colors of Super / LumiNova

There are different “grades” of Super-LumiNova for different uses and prices:

• Standard 
• Grade A 
• Build X1 

Grade X1 is twice as efficient as standard Super-LumiNova.

The Super-LumiNova, like the classic LumiNova, is available in different colors, both raw and once illuminated. Raw color may be different from illuminated color. The darker the natural color, the less it will illuminate.

For example, a black index will illuminate less than a red one, a red one will illuminate less than a light blue one, etc. *see graph*

Conclusion

These days, if you buy a new watch, you will almost certainly have Super LumiNova on the dial and hands. This material presents no danger and will accompany you for the entire life of the watch. Extremely reliable and customizable, it offers a wide variety of colors: enough to delight manufacturers.

For the second-hand market, be careful and be aware of the risks of Tritium and Radium, use our article to recognize them!

OUR MARIE SUPER-LUMINOVA COLLECTION

SOURCES:

• Photo Cadran Omega : Chrono-Shop
• Photo 2 Montres SuperLumiNova : Chasogolik
• Illustration Lip : Musee-Lip
• Photo Radium Dials: Ebay: DoughBoyWatches
• Illustration LumiNova : The Naked Watchmaker