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You may have seen that Lewis Hamilton made headlines over the weekend at the Monaco Grand Prix. Sadly it wasn't so much for his performance on the track (though, impressively, he bagged fastest lap). Rather, eagle-eyed timepiece fans spotted a new type of IWC on his wrist, and so the watch web went into meltdown.
It has now come to light that this all-white watch is not a production timepiece from the Swiss luxury watchmaker, but a one-off concept Pilot’s Chronograph with a world-first luminous ceramic case. IWC calls the proprietary material “Ceralume,” and has combined it with a luminous dial and luminous rubber strap for a watch that glows from its every surface. The effect is startling—a high-end horological version of those stick-on ceiling stars that blew your mind the first night your folks put them up.
It’s no surprise that the watch was debuted to the world on the wrist of Hamilton; the brand has worked with the seven-time Formula 1 world champion to create limited-edition designs before, and in 2020 even made him a one-off Big Pilot’s Perpetual Calendar in “Ceratanium,” its proprietary blend of ceramic and titanium. But this is the first time Hamilton has been given a prototype design to model. WIRED spoke to Lorenz Brunner, head of IWC’s research and innovation department, to find out what makes it so special.
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“A concept watch gives us the opportunity to test out the market,” says Brunner. “And to be honest, I have been working for 12 years with IWC and haven’t experienced anything like this.” There’s no doubting the watch’s all-over glow is quite a party trick, but IWC has engineered it for more than just Instagrammable moments. By infusing Super-LumiNova (a material that stores light energy) throughout the ceramic case, it has achieved unmatched levels of luminosity. Yes, unmatched is a mighty big claim, but Brunner says that IWC tests in a dark room showed that the Ceralume case could glow for up to 24 hours straight.
Ceramic watch cases are almost always made from zirconium oxide, also known as zirconia, which starts as a powder before being placed into a mold and sintered at a high heat, then milled into its final shape. The sintering process can have various side effects on the raw material; it not only shrinks the case from its starting size, but can also alter the color. It turns out that introducing a luminous compound complicates the procedure even further.
“The difficult part here is that we had to mix two different kinds of substances,” says Brunner. “One is the well-known zirconia powder, the other one being the Super-LumiNova, which is also a ceramic-like material. Chemically speaking, it’s strontium aluminate doped with rare-earth metal atoms. With these two materials, you have different densities. Also, the grain size is different.”
Brunner says that to achieve consistent luminosity and a clean appearance, the two powders had to be perfectly evenly distributed. This is achieved by using a ball milling machine that effectively tumbles the powders together like a rotary dryer filled with ball bearings.
“It’s not so easy, because you might agglomerate the heavier one on the bottom and the lighter one on top,” says Brunner. “You can play with the number of balls, what type of balls you use, the size of the balls, the container size, rotating speed, how long you make the whole process.”
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After months of trial and error, the final result, achieved by working with the same specialist supplier that creates IWC’s existing ceramic cases, was a ratio that found “the optimum balance between mechanical properties and luminosity.”
That was far from the only hurdle to clear, however. While standard oxide ceramics are sintered in a normal, oxygen-rich atmosphere, it turned out that under those conditions, the Super-LumiNova would degrade: It needed to be fired in a special mix of inert gases. “This was really challenging, because that’s not the standard way of sintering zirconia,” says Brunner. “I would say this was the most difficult part.”
Having figured out how to make the case and ensure a smooth even glow, the IWC team then had to make sure the end result lived up to the same standards of durability expected of a normal ceramic watch, famed for their scratch resistance and surface hardness.
Other watch brands, including Bell & Ross and Zenith, have created fully- or partly-luminous watch cases by infusing fiberglass, quartz, or carbon polymers with Super-LumiNova. But none had attempted it with ceramic until now. “When you have ceramic, the scratch resistance and durability is on a completely different planet,” claims Brunner.
“When we mix zirconia with Super-LumiNova, as material scientists, we call it [a mix of] structural ceramics and functional ceramics. Structural ceramics give the physical stability of a material, and functional ceramics a certain function, in this case the luminosity,” says Brunner. “When you mix two of them together you will probably lose some of the mechanical stability, because when you have 100 percent zirconia, you have full strength.”
"What we found out is that in terms of hardness, measured with Young's modulus, we are at the same level. So the scratch resistance will be exactly the same as a standard ceramic. We reduced the fracture toughness a little; if you drop 100 pieces, the risk of breaking some of them would be higher when you introduce Super-LumiNova. But the reduction is surprisingly not that dramatic. We did all the [normal] testing internally, with the shock tests ranging from 25G to 5,000G, and it passed all the tests.”
The longevity of the Ceralume watch’s luminous glow is a direct function of the sheer amount of Super-LumiNova present; despite being interspersed with ceramic, it is capable of absorbing a significant amount of energy from sunlight.
The case, meanwhile, is impervious to UV damage. “It depends on the sheer mass,” confirms Brunner. “If you imagine, normally in a standard watch, you have hands and maybe some indices that are in Super-LumiNova, which is a very low amount—fractions of grams. Here we’re talking about a whole case, and also in the strap you have more Super-LumiNova.”
The strap, Brunner says, is comparatively simple to engineer, without the concerns of sintering, shrinkage, and color fastness. “Of course, one important thing is to get it completely homogeneous. That's always difficult when you mix, say, a plastic or a resin with hard particles,” he says.
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That need for homogeneity is one reason why IWC’s Pilot’s Chronograph Ceralume is, for now at least, just a proof of concept. Only three finished watches exist; the other two not given to Lewis Hamilton are also just prototypes, each with slightly different dials.
IWC’s press announcement ended by saying that the patent-pending technology “will form the foundation of future developments and releases,” so night-owl watch addicts will have to be prepared to wait. Still, it’s a safe bet that a commercially available watch using this new case material is being developed.
Thus far, the Ceralume project has taken two and a half years, Brunner says. “To be honest, for a material science project, it was pretty fast. But it is a huge difference to present a concept watch to a series of a hundred or a thousand watches. In terms of process stability and so on, it's a different ball game. For example, on Ceratanium, I was working five and a half years to launch the first watch, just as a comparison.”
Of course, it is far from clear that a production watch would ever be quite such a head-turner. Brunner confirms that, during the development process, IWC experimented with different colors before settling on the blue shade used in the prototype. It’s also worth remembering that in addition to typical ceramic elements, like a dive watch’s bezel, the company also incorporates ceramics into its movements (for their low-friction properties), so the possibilities are many.
The message from this launch, however, is clear: IWC has a bright future ahead.
