Glowing Materials: Evolution from Radium to Super-Luminova in Watch Dial Technology

In the pocket watch era of the 18th and 19th centuries, if you wanted to read the flashing time on the dial in poor lighting conditions, you had to rely on zinc sulfide that slowly glows when excited by the sun or light; however, the effect of this material is very general and not noticeable, and the luminous light will quickly disappear. Therefore, when Marie Curie discovered radium in 1898, it became possible for watches to easily read the time in the dark. However, radium contains a lot of radiation and can cause serious damage to the human body, so it was later replaced by tritium gas with a small amount of radiation.

In modern times, Super-Luminova, jointly developed by Japan and Switzerland, is used as the main luminous material. Of course, there are thousands of luminous watches, especially with the current trend of sports watches, the importance of luminous function is even more irrelevant. The author selected several unique luminous watches based on their luminous style, styling design, or their own topics to show their private charm in the dark.

Radium

Radium contains a lot of radiation components and emits alpha and gamma rays with a half-life of up to 1,600 years. Radon gas is produced during the natural decay process and has extremely strong radiation. As for the earliest application of radium in wall clocks, it dates back to around World War I (1917). At that time, the American Radium Luminous Material Corporation asked a group of female workers to apply radium compounds to the hour markers and hands on the dial at its factory in New Jersey to produce luminous light.

Tritium

Tritium is also a radioactive element that emits light after decaying with beta rays. Its half-life is 12.43 years. Tritium will release a trace amount of electron flow, so it can stimulate the luminous paint to glow. Adding different contents of phosphide can stimulate different colors.

Super-Luminova

Luminova luminous materials were first produced by the Swiss RC Tritec company and first applied for independence by the Japanese Nemoto & Co. company. The two companies formed a joint venture in 1998, LumiNova AG Switzerland, and officially named this luminous material Super-Luminova. Its main component is strontium aluminate salt (SrAl2O4), which has photoluminescent properties and can be excited by light to emit night light, among which ultraviolet light has the best effect. It is non-radiative and environmentally friendly and meets the needs of the times.

Chromalight

It is an exclusive luminous material developed by Rolex in 2008 and first appeared in the Rolex Deepsea series. It is composed of a powder of metal oxides such as aluminum, strontium, dysprosium and europium, and is artificially combined with resin, and is evenly coated on the hour markers, hands, and the inverted triangle mark at 12 o'clock. Chromalight turns into crystals after high temperature and emits blue luminous light, which is about twice as bright as ordinary luminous light. Many Rolex sports watches now use Chromalight luminous paint.

miniature gas lamp

The self-luminous micro gas lamp (3H) exclusively developed by BALL Watch places tritium gas in a stable state in a hollow mineralized glass tube with an inner wall sprayed with cold light material. It is excited by electrons and produces night light. Micro gas lamps are small and light, so they are suitable as luminous lights for watch details such as scales and hands. Its brightness is 100 times that of ordinary night light, and its lifespan is about 25 years.