Boer’s Engineer Master II Diver GMT diving watch.
 Bohr’s method is to seal radon as a pure gas in a hollow mineralized glass. The inner wall of the glass is coated with a layer of luminescent paint, which is excited by the radon to emit light.
 Principle-The phenomenon of luminescence of matter is generally divided into two categories: one is that the substance is heated to generate heat radiation and emit light, and the other is that the substance is excited to absorb energy and then transition to an excited state (unstable state) and then return to the ground state. Release energy in the form of light. The use of fluorescent coatings on watches uses the second type of principle, that is, fluorescent materials emit light when excited. Of course, other than that, such as fluorescent lamps for daily use, fluorescent screens on televisions and computers are the second type of light emitting principle.

Piaget’s new Limelight Paradise series Altiplano in 2009
 Mother-of-pearl dial decorated with silver and overall luminous coral
The appearance of the watch is to facilitate people’s lives, but reading the time in a dark place is still very troublesome, and other light sources must be used. Of course, the minute repeater can partially solve this problem, but intuitively seeing time is still one of the important reasons why people like watches. Therefore, some people began to apply fluorescent materials on the hour and scale of the hands and dials so that the time can be easily read at night.

Citizen’s Eco-Drive Super Sky Eagle’s luminous is made of environmentally friendly materials
Traditional fluorescent coating materials can be divided into two types: self-luminous and light-storing. Self-luminous fluorescent agents mostly rely on self-carrying traces of radioactive substances to release light to excite the fluorescent agent to emit light. The light-storing fluorescent agent basically does not contain radioactive materials, but it needs to absorb and store sufficient external light in advance to transfer its electrons from a low energy level to a high energy level and store it. When the surrounding environment is dark, it gradually releases the absorbed energy gradually. At this time, the electrons transition from a high energy level to a low energy level, and the fluorescent agent starts to emit light. Since the light-storing type itself does not carry ray-excitation materials, the persistence of afterglow is temporarily inferior to that of the self-emitting type.

Bell & Rose’s BR01 simple dial features large coated hour markers
Several early common fluorescent coating materials
 Early relatively common fluorescent coatings used radioactive radium salts as activators. Due to their own radioactivity, they have been gradually restricted in use, and have now gradually been phased out. At present, the excitation materials are generally fluorescent agents containing thorium (3H or T), thorium (Pm), and radioactive radium sulfate (Ra), and the fluorescent agents are mostly zinc sulfide, calcium sulfide or strontium sulfide, and other zinc sulfites. Although thorium (3H or T) and thorium (Pm) are still radioactive, the potential damage to the human body is much smaller.
Blinking in the dark on a big-name watch = light copied from the international brand information website, flashing in the dark on a big-name watch
Thorium (3H or T) is an isotope of hydrogen. The nucleus is composed of one proton and two neutrons. It is radioactive and undergoes beta decay with a half-life of 12.43 years. Although plutonium (3H or T) is also a material for making thermonuclear weapons, its beta decay will only release high-speed moving electrons and will not penetrate the human body. Only a large amount of contact and inhalation of plutonium (3H or T) will cause harm to the human body. hurt. Phosphorus (3H or T) fluorescent agents use high-speed electrons released in beta decay to excite luminescent substances. In addition, plutonium (Pm) is a fluorescent radioactive stimulant similar to plutonium (3H or T), with a half-life of 17.7 years.

Airboss Limited Chronograph by Vickers Army Watch
 Various dense time scales and scales are coated with fluorescent materials
 Due to its own radioactivity, the application of radioactive components such as plutonium (3H or T) in fluorescent agents has been strictly regulated many times in the world. According to ISO3157, activated fluorescent coating materials using thorium (3H or T) and thorium (Pm) must be marked with T or Pm, indicating that their radioactivity is less than 227 MBq (7.5 m Ci). In addition, for watches such as flight watches or diving watches, when the radioactive coating on the dial is highly radioactive, the critical dose T & lt; 25, or T25, Pm 0.5, etc. must be marked, indicating that its radioactivity is less than 925MBq (25mCi). For most watches, the trace amount of radiation emitted by the fluorescent agent will be absorbed and blocked by the metal case and the ore mirror, but these rays can still penetrate the traditional acrylic glass mirror. Therefore, some early military watches will have prominent warning signs, such as H3 or T with an outer ring to warn, please do not continue to wear when the mirror is broken. In addition, the use of radioactive radium sulfate (Ra) is strictly restricted, and is generally only used in aviation instruments and deep-dive instruments.

Rolex’s Oyster Perpetual Sea-Dweller DeepSea
 The use of special luminous materials has a longer luminous time. Moreover, its blue luster can easily read the time even at the bottom of the sea at 3900 meters. Modern non-radio fluorescent materials have been developed since the 1990s with the development of science and technology, and a new type of long-glow storage without radioactive materials has appeared. Type rare earth based alkaline earth aluminate fluorescent material. It is fundamentally different from traditional sulfide and radiation-excited noctilucent materials. It does not contain any harmful elements at all. It has more stable chemical properties, high brightness, and long afterglow time. Long afterglow energy storage luminescent material is a kind of photoluminescence material that can be excited by any kind of light energy such as sunlight and light. The basic luminescence principle is: during the material preparation process, the doped element forms a luminous center and a trap center in the matrix. When excited by external light, the ground state electrons of the luminous center transition to the excited state, and when these electrons transition from the excited state When returning to the ground state, luminescence is formed. At the same time, some electrons fall into the trap center when they are stimulated and are bound to complete the energy reserve. After the light is removed, the electrons bound to the trap jump out of the trap and fall to the ground state due to the disturbance of the ambient temperature. The released energy excites the luminous center to form luminescence. Because the electrons bound to the trap gradually jump out of the trap due to the disturbance of the ambient temperature, the light emission appears as a long process, which forms a long afterglow.

Tissot Starfish Diving 1000 Automatic Watch
 The fluorescent coating on the time scale is designed as Tissot’s signature ‘T’. Among them, the registered patented technology of Nemoto and Co Ltd., Luminova and Superluminova materials, are widely used in watchmaking. Many watch manufacturers are now gradually adopting these new fluorescent materials, and the ‘T SWISS MADE T’, which once dominated at 6 o’clock on most dials, has gradually changed to a ‘SWISS MADE’ that indicates that it no longer has radioactive material. After the new type of fluorescent material is irradiated by strong light, the afterglow effect will last for several or even ten hours.