Super-Luminova, on the other hand, uses no ‘excitant’ at all. Five years later, RC-Tritec AG partnered with Nemoto in establishing LumiNova AG Switzerland, which supplied the material in the Swiss watch industry. The idea for Luminova is to have phosphors that will continue to glow for hours, even without the help of radioactive ‘excitants.’ It was invented in 1993 by Nemoto & Co., a Japanese company. Luminova and Super-LumiNovaĪs the search to find another substitute material not radioactive at all continues, and this is where the two super players in the modern watchmaking industry come in the Luminova and Super-Luminova. This makes the former a better ‘excitant’ for achieving luminous dials. Tritium is estimated to have a half-life of 12.32 years, while promethium only has 2.62 years. On the other hand, tritium is also a low energy beta emitter with a longer half-life than promethium. Promethium emits only beta particles at lower energy and used as an ‘excitant,’ so the dial can emit visible light. Technically, these two substances are considered less radioactive than radium. Promethium and Tritiumĭue to the harmful effects of radium paint, promethium and tritium were later discovered as substitutes. However, given its dangerous effects in health, it is not almost used today in the modern watchmaking industry. While this illuminates’ dials in watches, it has disadvantages: 1.) it is chemically unstable, and 2.) it is a radiological hazard.īack in the old days, some watches had numbers and indexes with radium paint. There is no need for an external energy source because there is already light emitted from the radium particles' radiation in the paint. This material is self-luminous, only when freshly applied. Other Materials Used for Luminous Dials Radium Paint The only difference is that they emit those photons as light very slowly, which is why phosphorescent paints are usually used for watch dials. Phosphorescence – Phosphorescent materials also absorb photons from a light source. For watch dials, using fluorescent materials is not always viable. Hence, most of these materials will go dark right away once the light source becomes unavailable. They will continuously glow if there is a light source, but the emission of particles occurs on mere nanoseconds. There are two known types of photoluminescence:įluorescence - Fluorescent materials emit absorbed energy very rapidly. By this time, the material starts emitting the photon, which we see by our naked eye as visible light. To simplify, if an electron atom in a material absorbs a photon, it gets excited, reaching a higher energy state until it goes back to normal.

As defined, light has packets of energy known as photons, which are quantum particles in an electromagnetic field. It is a particular case of photoluminescence or certain elements' ability to emit light after exposure to a light source. The Luminous Dial’s Glowing PropertyĪny materials that can glow in the dark are visible phosphorescence. For timepieces to have this glowing property, the basic knowledge about chemistry and physics can help us understand how it works and adequately handles such hazardous material. It is essential to understand the history of luminous dials and the science behind its concept. It has interesting facts that are uncommon to most watch wearers. It is one reason why glowing dials have been an ongoing subject between watch collectors. While luminous dials are standard in dive watches, there are also casual timepieces with the same property. Due to its luminescent property, divers maintain better visibility even in the dark environments, preventing them from any imminent dangers that may arise while submerged in the water. This characteristic helps divers navigate underwater easily. Aside from the rotating bezel, another distinct part of a dive watch is its dial with luminous hands and indexes.

Watch hand luminous paint