Watches with strong luminosity

Even the most precise, reliable watch is of little use if you can't read it. In the dark, many watches lose their usefulness. This is different with models that glow in the dark. These special timepieces, used in diving watches and military watches, for example, defy adverse lighting conditions and have been shaking up the watch world for some time. This article is dedicated to wristwatches with luminous material, compares the different luminous materials, and presents selected women's and men's watches with luminous numerals and dials.

What does “strong luminosity” mean?

For use in watches, luminescent materials that exhibit a certain luminosity without requiring significant heating are particularly interesting. While many materials begin to glow with sufficient heat, this heat cannot be generated during everyday use of a watch. Just imagine having to take off your everyday watch at regular intervals to warm it up – that's simply not practical. Furthermore, in this case, all the materials used would have to withstand the required heat. This would undoubtedly severely limit the choice of materials.

For watches to glow in the dark, they need a phosphor that exhibits what's known as cold light emission, meaning it emits light without requiring intense heat. This is called luminescence.

To put it simply, luminescence is triggered by the activation of atoms or molecules through chemical, mechanical, or electrical processes, provided the appropriate means are used. During these processes, energy is generated, which is subsequently released in the form of light—the watch acquires luminosity. The intensity of the luminosity is typically defined by the brightness of the light or the duration of each individual process.

Types of luminous materials

The watch industry now offers a wide variety of different materials and luminous colors that can help illuminate hands, indices, and dials. Below, we take a closer look at the most common, most widely used, and most historic luminous materials for watches:

radium

What may seem strange from today's perspective represented a breakthrough for the Italian watch brand Panerai : radium watches. In 1914, the founder of the long-established company, Guido Panerai, patented the phosphor Radiomir, which was based on radium bromide and, in combination with zinc sulfide, produced a permanent, heat-independent glow. Such luminous materials could thus illuminate watches for long periods of time—measured by the half-life of radium, actually over 1,600 years—without the need for recharging.

Some readers may now be wondering how dangerous it is to wear radium watches. After all, radium is generally known for its radioactivity. The answer is quite surprising: Radium incorporated into a watch as a luminescent material is virtually harmless to the wearer. But how is that possible? Quite simply: In the Radiomir watches, the radiation from the radium luminous material was largely absorbed by the case, thus having only a minor effect on the wearer.

However, the buyers of the watches didn't even need to be convinced of this fact, as there was little skepticism towards the material among the population at the time. Quite the opposite: Radium was even advertised as healthy and used in a wide variety of foods, care products, and medicines. Even if this is hard to imagine today, there were radium drinking cures, chocolate with added radium, and radium-containing toothpaste. Consuming radium—or wearing it on your wrist—wasn't a cause for concern, but rather a feeling of doing something good for yourself. It wasn't until much later that radioactivity was associated with all sorts of health risks.

The catch: The watches had to be produced somehow; the workers inevitably came into contact with radium, and the radioactivity certainly left its mark on them. While they were harmless to the wearer, they were equally harmful to those involved in the manufacturing process. The catchphrase here is "Radium Girls." This is what the workers who handled the luminous material on the opened watches, ingesting large amounts of radium, were called. Several of the Radium Girls subsequently had to battle serious cancers – the total number of deaths caused by radium watches is not documented.

Tritium and tritium gas

As knowledge of radium's significant disadvantages grew, the need for an alternative became increasingly urgent. In the 1960s, tritium, a hydrogen isotope with a twelve-year half-life, was finally introduced. However, this by no means solved the problem of radioactive radiation, as tritium is also radioactive, albeit less so than radium. Using tritium was certainly an advance, but it quickly became apparent that it had not yet provided a definitive, truly sustainable solution.

As a result of the further development of tritium luminous material, tritium gas, GLS Tritium H3, was soon incorporated into watches. The gas was filled into phosphor-coated glass tubes, which were designed to minimize radiation, and for the first time allowed the creation of color effects in the resulting light. The tritium tubes were used as hands and indices in H3 watches and certainly fulfilled their purpose: They made it easier to read the watch even in darkness and poor lighting conditions.

Today, Tritium H3 watches are marked with the symbols T, T25, and H3, which are usually found on the dial. Timepieces with tritium as a luminous material have not been manufactured since the 1990s.

LumiNova

The development of the LumiNova phosphor by the Japanese company Nemoto ushered in a new era in luminous watches. For the first time, it was possible to make watches glow without radioactive side effects—a huge milestone. Instead, this material, consisting of alkaline earth luminates, is charged by external light—whether artificial or daylight—with the luminosity being measured by the intensity of the charge. LumiNova is therefore a so-called afterglow color that can be used to create light in a wide variety of colors.

Super-LumiNova

The substance that makes watches glow is now known as Superluminova C3, Chromalight, or LumiBrite. Which name you find depends largely on the manufacturer you're looking at. Essentially, they're always the same product, albeit in slightly different versions. The background: In the 1990s, both the Swiss company RC Tritec and the watch brand Seiko had the opportunity to purchase the luminous substance from Nemoto almost simultaneously and market it under different names.

While LumiNova has a maximum luminous duration of five hours, watches with Super-LumiNova glow for up to 15 hours before their brightness and luminosity slowly but surely decrease, requiring recharging. As versatile luminous materials, Super-LumiNova, Chromalight, or LumiBrite can be used as luminous paint in green, orange, or blue, for example, with the blue phosphor being particularly popular for diving watches.

How exactly Super-LumiNova watches appear in the dark varies from brand to brand and from product to product. There are now watches with the entire dial illuminated by the luminous material, light-framed straps, luminous logos, and, of course, the classic luminous hands and indices. Watch brands often succeed in seamlessly integrating the Super-LumiNova coating into the design, creating an optimal overall appearance.

Advantages and disadvantages of different phosphors

To complete the overview of the common luminous materials for watches of the past decades, we will venture a comparison and briefly discuss the specific advantages and disadvantages of the individual luminous colors.

The disadvantages that led to the demise of radium and tritium are obvious. The radioactivity of these luminous materials made them dangerous, especially for workers who had to handle the materials openly. While tritium is less radioactive than radium, it loses its luminosity after just twelve years and is still considered potentially hazardous to health. However, one major advantage of these two formerly popular luminous materials should not be overlooked: they required no external power source and did not require regular recharging. However, this advantage cannot, of course, compensate for the health risks and problems associated with the manufacture, maintenance, and disposal of tritium and radium watches. It is therefore hardly surprising that such items are no longer produced today.

Compared to this, tritium gas can be considered harmless and is therefore more suitable for use in watches. This luminous ink also glows continuously. Therefore, no external energy source is required to illuminate a watch with tritium gas. The drawback: Tritium gas is tied to the half-life of tritium, which is why the light fades after about twelve years.

Which brings us to LumiNova and Super-LumiNova. Both luminous colors have the huge advantage of being harmless, non-radioactive, and therefore significantly less risky to use. However, unlike tritium, for example, LumiNova and Super-LumiNova rely on external light sources to function as luminescent materials. They must be charged by light exposure to perform their function, and this must be done regularly. The difference between the two products mainly relates to the luminous duration and the luminescent colors. LumiNova can be seen glowing at full intensity in the dark for a maximum of five hours, while Super-LumiNova lasts for a full 15 hours. Furthermore, significantly more color variations are available with Super-Luminova, multiplying the visual design possibilities for dials, indices, hands, and the like.

The best watches with strong luminosity

Whether with LumiBrite, Superluminova, Chromalight, or a similar, safe luminous material, many manufacturers offer watches that glow in the dark, making them ideal for outdoor adventures in the dark. Six of the most popular products of this type are presented below:

Omega Seamaster 300M

A watch that immediately catches the eye and delights collectors around the world: the Omega Seamaster Diver 300M. Water-resistant to a depth of 300 meters, this watch impresses with its sporty design and outstanding functionality. Since the first Seamaster was launched in 1993, these watches have almost consistently been among the most sought-after models of their kind. This is probably due in no small part to the Seamaster's outstanding readability in the dark. This is an indispensable feature, especially for divers, for whom the watch was originally designed.

To ensure this, Omega equips its watches with Super-LumiNova. This luminous material makes the hands and, where appropriate, the pearls on the dial glow green and blue in the dark. The dial itself features the wave pattern, a hallmark of the Seamaster and giving the timepieces their very own charm. The Seamaster 300M with Superluminova is available from the manufacturer with a metal bracelet, NATO strap, or robust rubber strap.

Rolex Submariner

The Rolex Submariner is the epitome of a modern, highly functional diving watch. The manufacturer promises optimal legibility, even in the depths of the underwater world, and uses Chromalight for this purpose. The luminous color is a distinctive blue and boasts a luminous duration of up to eight hours. The luminous material is applied not only to the hands and indices but also adorns the chaton on the bezel.

And beyond its Chromalight finish, the Submariner certainly has a lot to offer. It's water-resistant to 30 bar and, thanks to the 60-second engraving on the bezel, helps you read your dive time precisely. This premium watch is made from Cerachrom, a material that's particularly scratch-resistant and resistant to chlorine and salt water.

Panerai PAM 632

Having already mentioned the renowned Italian watch brand Panerai several times in this article, we now take a look at a particularly popular model from the manufacturer. The PAM 632 is a hand-wound men's watch whose design strikes a balance between down-to-earth classicism and modern sportiness.

The watch from the Luminor Marina collection boasts an 8-day power reserve, a deep brown dial, and a solid case made of durable stainless steel. The luminescent material used, which makes the PAM 632 watch perfectly legible even at night, is—unsurprisingly—Luminor. This material can be found on the indices, hands, and numerals on the dial.

Breitling Navitimer

As a coveted pilot's watch, the Breitling Navitimer is a collector's item that has delighted the watch world for around 65 years. Breitling watches are now available in a wide variety of designs – some sporty, some classically elegant. All models have one thing in common: the integrated luminous material ensures optimal readability.

Breitling now uses the luminous paint Superluminova, which can be found on the Navitimer timepieces both on the indices and on the minute and hour hands. In use, a Navitimer watch, as confirmed by wearers' experiences, is said to offer a consistent luminous duration of at least eight hours. Connoisseurs largely agree: Among Super-LumiNova watches, the Breitling Navitimer is among the best.

Nomos Glashütte Autobahn

If there's one modern watch that embodies the passion for high speed and pure movement, it's arguably the Autobahn Chronograph from Nomos Glashütte . The domed dial, the three-track date window, and the precise neomatik movement are just a few examples of the outstanding details that distinguish this watch. What appears straightforward and simple at first glance actually contains an unexpected complexity and a variety of functions that one has come to expect from Nomos Glashütte for years.

Designed for frequent drivers and those who are often on the road at night, the Autobahn watch naturally glows in the dark. Nomos Glashütte uses Super-LumiNova for this effect, and the luminous paint is used quite generously. The watch dials feature a comparatively wide blue luminous ring, briefly interrupted every five minutes – this illuminates almost the entire dial and makes them easy to read. In addition to the highly illuminated dials, the hands are also coated with Super-LumiNova, creating a harmonious overall appearance both in daylight and in the dark.

Maurice Lacroix AIKON Venturer

The last watch with luminous colors we'll cover in this article is the AIKON Venturer by Maurice Lacroix. Intended as a kind of homage to the Lacroix Calypso series of the 1990s, the AIKON Venturer collection amazes with its incredible diversity. It includes a wide variety of men's and women's watches and is certainly not afraid of extravagant color schemes. Models from the AIKON Venturer collection are available in bright pink, a fresh mint, or a striking yellow and blue color combination.

The hands and indices on the AIKON Venturer's dial are coated with Superluminova. The luminous color blends seamlessly into the design and further underscores the watches' distinctively modern character. Thus, the Lacroix models are a perfect example of how Superluminova can serve a valuable purpose not only functionally but also visually.

Conclusion

From radium to tritium, and finally to today's modern luminous paints like Super-LumiNova, Chromalight, and LumiBrite, the watch industry has come a long way in terms of luminous materials. Perhaps the greatest progress has been made in terms of health risks: While the production of luminous watches used to pose health risks – if not for the wearer, then certainly to a great extent for the workers in the production process – these practical models can now be produced completely safely. As a result, we can enjoy the constant flow of new, easy-to-read watches with luminous paint. These watches also benefit from the design of Chromalight, LumiBrite, Superluminova, and others.