Some of the very first applications of luminous paint (lume) can be found on military pocket watches from the early 1900’s. Initially, luminescence was achieved by using a radioactive material called radium, which was first discovered by Marie Slodowska-Curie and her husband, Pierre Curie in 1898. Radium was combined with zinc sulfide, which allowed for a brighter glow than pure radium alone. You can see this on a number of vintage Rolex watches that have managed to survive to this day and still have their original luminous dials and hands.
Since then, the entire industry has shifted to much safer options, including Rolex. As with everything the company does, Rolex continued to evolve and search for the perfect luminous material used on its watches, with Chromalight being the latest and greatest of them all. Let’s take a closer look at the various luminous materials Rolex has used over the past several decades, from Radium to Chromalight, and everything in between.
Radium – The First Rolex Luminous Material
The lume used on vintage Rolex watches was radium-based, and radium remained the standard for nearly all Rolex lume until 1963, when growing health concerns forced a shift away from it. During the early 1900’s, the effects of radiation exposure were not well understood, and radium was frequently marketed as a magical “cure-all” intended for human ingestion.
Even after radium exposure was proven to be harmful in the late 1920’s, it was still used (in moderation) for several more decades. Due to the dangers, factories implemented safety protocols, and radium continued to be used on watch dials until the early 1960’s.
Although there were safety measures in place, growing health concerns pushed Rolex to abandon radium altogether in 1963. With radium ruled unsafe, tritium became the luminous material of choice for Rolex. Just like radium, tritium was also radioactive; however, it came with a much lower level of radiation and a much shorter half-life.
Tritium – A Safer Radioactive Alternative
While tritium was exponentially safer than radium, it only had a half-life of a little over twelve years. This meant that after just a couple decades, only a tiny fraction of the initial luminescence would remain. Additionally, as tritium ages, the color changes, which creates interesting patinas on the luminous markers of older Rolex watches. Some like to re-lume watches, while others love the patina.
Despite being substantially safer than radium, tritium was still radioactive, and as a result, many watchmakers of the time (Rolex included) marked the dials with an indication of the level of radioactivity emitted by the watch, such as “T Swiss T”, or “Swiss T<25”.
Tritium was far from perfect, which led Rolex to search for a better alternative. The answer came during the 1990’s, from a Japanese company called Nemoto and Co., which specialized in producing luminous paint. Their new compound, called Luminova, was photoluminescent rather than radioactive, making it entirely harmless. Additionally, it was not prone to fading or discoloration like its predecessor, tritium and could instantly be recharged by just being exposed to light.
Super-LumiNova and Chromalight
Luminova was far saver and considered superior to tritium, with the only downside being that it required prior light exposure in order to glow, rather than glowing perpetually due to being radioactive and by 1998, Rolex began using it on all of its watches. By 2000, Rolex had switched to Super-LumiNova, a Swiss-Made version of Luminova that was sold through a different supplier.
In 2008, Rolex announced a switch from Super-LumiNova to its own proprietary compound, Chromalight. Like its predecessor, Chromalight is photoluminescent and entirely safe; however, Chromalight differs in that it glows blue rather than green. Rolex states that Chromalight starts glowing more quickly and lasts longer than Super-LumiNova (up to eight continuous hours, to be exact) and that the blue color makes it easier for human eyes to read in dim lighting. Chromalight is also celebrated for its crisp white hue during the daytime.
Beyond that, Chromalight gives modern Rolex watches a distinctive appearance in dark settings and brings yet another aspect of their production process in-house. Therefore, depending on the year of production of the specific watch, that is what makes a Rolex glow in the dark.
Rolex Luminous Material Timeline
Below is a quick recap and overview of the history of Rolex’s luminous material.
- 1963: Rolex stopped using Radium due to growing concerns surrounding the material’s health risks and switched to Tritium.
- 1998: Luminova, produced by the Japanese company Nemoto and Co, replaced Tritium.
- 2000: After just a few short years, Rolex switched from Luminova to Swiss-Made Super-LumiNova.
- 2008: Rolex brought the production of their luminous material in-house, replacing Super-LumiNova with Chromalight, which it continues to use to this day.
Whether it’s Tritium in a deep, buttery patina or stark white Chromalight, the luminous material on any Rolex has a lot to say about the watch. In fact, there are many benefits to all of the materials mentioned in this article. It ultimately comes down to personal taste and the vibe you’re searching for in a Rolex watch. Which Rolex luminous is your favorite?