This is the last of three parts of our special on composites in watchmaking. Part 1 saw watch editor Ashok go into the nitty gritty of what composites are and how they figure in watchmaking. Part 2 ran through in brief the history of composite materials throughout human civilisation while Part 3 features contemporary use of composites and recent engineering feats in watchmaking.

Carbonox

It should be no surprise that proprietary composites are found at various levels of watchmaking, especially carbon composites. Nevertheless, Luminox stands out for its use of a proprietary carbon composite called Carbonox, first deployed in 2016 for the case of the Luminox Master Carbon SEAL 3800 series. As usual with such proprietary developments, little is known about the process to make it or what goes into it, except what Luminox tells the world. To begin with, Carbonox is a lightweight and durable material designed to provide enhanced resistance to shocks, scratches and other forms of wear. Carbonox is also six times lighter than steel, three times lighter than titanium, hypoallergenic and antimagnetic.

The simplest explanation for Carbonox is that it is made up of carbon fibres mixed with a high-strength polymer resin. Given the look of the material, it is more than likely that Carbonox is more like forged carbon than carbon fibre. Another more detailed description, again from Luminox, states that it is made up of long bar carbon compounds, with carbon fibres making up 40% of said compound. This combination of materials results in a material that is strong and lightweight, with excellent impact resistance and high durability. Carbon fiber is known for its high strength- to-weight ratio, and when combined with the resin, it creates a material that is tougher and more impact-resistant than traditional plastics or metals.

Luminox uses Carbonox in the production of watch cases designed to provide excellent protection for the watch movement and dial. The material is also used for other components, such as the bezel or case back.

In addition to its strength and durability, Carbonox has a unique look and texture that gives Luminox watches a distinctive appearance. The material has a matte black finish that is resistant to scratches and scuffs, making it ideal for use in outdoor and adventure watches.

Overall, Carbonox is a high-performance composite material that offers excellent durability and resistance to wear, making it an ideal material for use in the production of high-quality watches that are designed to withstand extreme conditions. 

Lightweight Strength

If nothing else, the introduction (Part 1) and the brief history lesson (Part 2) will have left you with the understanding that composites might vary in cost greatly, while synthetic jewels obviously offered great cost savings besides allowing watchmakers access to standardised materials. While the benefits of composites and synthetic crystals are related to a variety of emerging material properties, the value proposition is unclear (no pun intended). Would you, dear reader, consider forged carbon on par with gold? Perhaps you might consider exotic materials even more precious than gold? That last bit is exactly how Richard Mille saw things, with the watchmaker experimenting with extreme lightness as a way of counterprogramming against traditional wisdom in Swiss watchmaking.

A carbon composite has an excellent strength to weight ratio, with a given volume of material being less than a fourth the weight of the same volume of steel. A watch case that weighs 50g in steel will weigh about 10g in a carbon composite — now that is lightness you can feel. Obviously, not even all carbon composites have the same mass so lightness here is best understood as a relative proposition. Generally though, carbon composites are less dense than any solid, even aluminium, titanium and plastic; while synthetic resins are sometimes called plastic, there are many types of plastic and most are solids, not composites. It is worth noting that not all synthetic resins are actually plastic, as in made of hydrocarbon-derived material.

Digression aside, being featherweight is great but meaningless without strength. While it is not possible to generalise, the same mass of a carbon composite is roughly five times stronger than the equivalent mass of steel. Of course, what is light does not always sit well with people’s expectations, as Grand Seiko President Akio Naito told us some issues back. Some people prefer the heft of gold, for example. That is why even brands such as Hublot still have traditional materials in the mix. Nevertheless, having heard about the great properties of composites, you might be wondering why more watches are not cased up in this engineered material. The answer is complicated and comes down to machining challenges but also pricing and perception. We do offer three very specific examples in this story from watchmaking, for context and real talk about what composites mean for us all as people with a passion for watches and watchmaking.

Performance Matters

Before we get to those, we want to use this main section to cover something called metal matrix composites or MMCs, because this fancy-sounding stuff is the spine behind a lot of the composites featured here. MMCs are quite different from carbon composites primarily because ceramic takes the place of the usual synthetic resin. Here is literal mash-up of a definition, gleaned from the Internet (Wikipedia, Britannica, Sciencedirect.com) and a variety of AIs: in materials science parlance, MMCs are metals reinforced with fibres or particles to improve or tailor properties such as stiffness, strength, thermal conductivity, thermal expansion, friction and wear-resistance . There are two parts here: one is the metal matrix and the other is the reinforcing material, which can be a ceramic or even another metal. The reinforcing material is distributed evenly across the entire metal matrix.

It is not all rosy though, as this Princeton materials science textbook notes: “MMCs also have some disadvantages compared with metals. Chief among these are the higher cost of fabrication for high-performance MMCs, and lower ductility and toughness. Presently, MMCs tend to cluster around two extreme types. One consists of very high-performance composites reinforced with expensive continuous fibres and requiring expensive processing methods. The other consists of relatively low-cost and low-performance composites reinforced with relatively inexpensive particulate or fibres. The cost of the first type is too high for any but military or space applications, whereas the cost/ benefit advantages of the second type over unreinforced metal alloys remain in doubt.”

The first example of an MMC case in watchmaking appears to be the aforementioned Richard Mille RM009, and it did not open the floodgates. Unlike carbon composites which became a flavourful trend for a time, MMCs remain pretty exclusive. This is likely due to machining challenges and the prohibitively high cost of the original research and development. While watch brands do not typically tell us much about the “continuous fibres versus particulate fibres” issue, they do like to cite military and space industrial usage, so our presumption is that the MMCs in watchmaking are expensive and difficult to produce. Note the price of titanium matrix composites in the Ceratanium segment. 

Ceratanium

IWC is no stranger to material innovation in watchmaking, making significant contributions with both titanium and high-end ceramics. In 1980, IWC teamed up with Porsche Design to create what was one of the first wristwatches in titanium and in 1986, debuted the first high-complication wristwatch case in black zirconium oxide ceramic. What if the Schaffhausen-based manufacture could combine the two as a completely new cermet? Well, that is exactly what has come to pass with Ceratanium, IWC’s proprietary material that is “as light and robust as titanium but as hard and scratch-resistant as ceramic.” To be clear, Ceratanium might not be an MMC despite seeming very much like one — many expert sources characterise the material as a special alloy. We include Ceratanium in this section regardless because of how the material is made and because it might qualify as a ceramic-metal hybrid even if it is not an MMC. It is at least as much a composite as Achilles’ shield!

Now, IWC is clearly not the first to think about combining titanium and some sort of ceramic, like Al2O3, and we ourselves consulted academic papers on this subject from 1996. Even at this time, the virtues of titanium matrix composites (TMCs) were already well known, making TMCs sought-after in the aviation industry and the military industrial complex. One of the key issues with TMCs is that they are prohibitively expensive (US$1,000 per kg), so it is perhaps unsurprising that IWC only debuted what it calls Ceratanium in 2017 (with the Aquatimer Perpetual Calendar). The manufacture said it took five years of research and development to come up with Ceratanium, and we present below a paraphrased version of the official description of the machining process.

IWC begins its description by noting that Ceratanium is not merely a blend of titanium and ceramic. Nothing so pedestrian, if technically complex, would do for a high-end watchmaker. The manufacture begins with some sort of special titanium alloy, of which there are many in commercial use, but this one was developed to IWC’s specifications. Interestingly, all manner of case components can be executed in Ceratanium, from the casing ring to the crown and pushers. CNC machines turn and mill these components, but each one is sand-blasted by hand. This is not a finishing technique, but rather a means to create an uneven surface. The next part is a bit mysterious, but certainly has something in common with ceramics: the sand-blasted components are baked in a kiln in very specific conditions that allow for a “phase transformation” of the surface of the material. The crucial element here is oxygen which diffuses into the surface, a process we presume has been prepared for via the aforementioned sandblasting.

Anyone with a little knowledge about chemistry and physics will be squinting pretty hard at this point, but IWC is keeping mum beyond the above information. The effect of the Ceratanium seems confined to being black, thus proving superior to any sort of coating applied to a base metal. For IWC, this means that it can produce all-black watches where beauty is more than skin-deep. Furthermore, the watchmaker is able to produce even small pieces such as pushers in Ceratanium, allowing for an unmatched degree of uniformity.

Advancing Accessibility

Nevertheless, the cheaper alternative should not be forgotten, and is actually the reason Audemars Piguet retreated from the world of composite materials some years ago. Explaining why it stopped using forged carbon for its cases, Audemars Piguet noted that many other brands had begun using similar composites or the exact same composite but at much more accessible prices. This spoiled the party for the Le Brassus brand, and it might yet have been worse if the accessibly priced brands were using a material inferior but indistinguishable to what Audemars Piguet was using. Again, solid gold is solid gold no matter what and has the benefit of needing no explanation whatsoever. We dare say that it never will, unless it is called something like “Magic Gold” perhaps.

Before we get to those individual close-ups, we will finish off with carbon composites, which have come far in watchmaking since Audemars Piguet’s pioneering experiments with carbon fibre and forged carbon. Quite a number of brands are active in this area, with Panerai, Bell & Ross, Richard Mille, Roger Dubuis, Franck Muller, Zenith, TAG Heuer, Ulysse Nardin and Gorilla keeping the pedal to the metal. TAG Heuer in particular is still keeping us on tenterhooks about its carbon hairspring, although it does use it in its tourbillon models. Even surprising names such as H. Moser & Cie come up with its Vanta black dial being made of carbon nanotubes.

These relatively recent developments cover both the aesthetics and technical performance of traditional watchmaking, serving to illustrate that carbon composites are playing a part in all sorts of places. Even Patek Philippe would not eschew the use of carbon composites as long as such materials are confined to internal parts, according to Philippe Barat, Head of Watch Development at Patek Philippe. It already uses silicon and ceramic in its movements after all, so this should come as no surprise. Carbon composites also play a part in the making of sustainable watches as demonstrated by Ulysse Nardin’s Carbonium. This last one is the proprietary creation of French outfit Lavoisier Composites and is made up of leftover material from the aerospace sector – the stuff that made up the fuselage and wings of aircraft. Since Carbonium is repurposed carbon fibres (bound together with an epoxy also from the aerospace industry), it maintains its structural integrity (recycled materials however often do not have the same quality as the originals, unsurprisingly). Lavoisier Composites also makes something called Carbonium Gold, a carbon fibre and gold composite, and we are keeping an eye out for watch brands using something like this.

• READ MORE: Kering To Sell Girard-Perregaux and Ulysse Nardin

Finally, to wrap up our discussion on composites in general, a closing note: it is impractical to make sweeping statements about any particular kind of composite. As such, when you look into buying a watch that includes such materials, you will have to ask questions and be prepared for non-answers from dealers and even brand representatives. While this may not be a big deal when it comes to accessible timepieces from the likes of Zelos, Doxa or Luminox, it will loom larger in your mind as the air gets thinner at heftier price points.

Transparent Materials

This section was initially published in 2020 as a part of a ceramics material special under an alliterative tongue-teaser title: “Corundum Conundrum”. Corundum is the specific name for sapphire and defines all such materials, including rubies. Apart from attempting to be catchy, that original title highlights the problematic role of sapphire crystal as well as synthetic rubies used in movements. The problem is that corundum is actually aluminium oxide, or Al2O3, which is often called alumina. Yes, the very stuff Rolex opted for in its Cerachrom bezel, because the brand found a way to colour this version of ceramic that would not work with zirconia.

If you have been keeping up with this entire story, this means that sapphire crystal and synthetic rubies might be erroneously passed off as another sort of advanced ceramic. While we initially pointed out that Al2O3 could be considered either a crystal or a ceramic, that is only appropriate when referring to the atoms that make up the materials — if the discussion was about substrate elements. For the materials themselves, how those elements are bound to each other makes the difference. This is one reason why making a crystalline object is quite a different challenge from making a ceramic object. Also, crystal corundum exists in nature but ceramic does not.

The question then remains: is the process of making the powdered form of aluminium oxide that is moulded and sintered into a final ceramic shape the same as that of making and machining sapphire crystal? The simplified answer is no, but it is worth noting that one can make blocks of sapphire from aluminium oxide in its powdered form. This works for clear sapphire crystal, but getting a colour into the mix is a challenge despite the Verneuil process already being capable of delivering red sapphire crystal in the 19^th century. 

Colourful Storytelling

This is a great story for companies such as Chanel and Girard-Perregaux, both known for various ceramic and sapphire watches which include the use of such materials in their mechanical movements. It is inaccurate however to suggest that Chanel or any brand uses either one of those materials because they are actually interchangeable. It explains perfectly why a company such as Swatch Group-owned Comadur would be adept at working with advanced ceramics and sapphire crystal despite the fact that both require separate production lines. For this reason, identifying ceramics with sapphire would spoil the romance of some very impressive haute horlogerie feats of derring-do. Hublot, for example, has pioneered full cases in coloured ceramic and also coloured sapphire crystal, but it would be rightfully displeased to have these processes conflated. Then of course there are collectors, including you, dear reader, who have their own feelings about this. No doubt many of you will wonder if the recent turn towards bold colours in watchmaking will mean more experiments in case materials, for which both ceramic and sapphire crystal are well suited. The colours in either material will never fade and cannot be scraped off.

On that note, watches cased in sapphire crystal do not possess the structural strength of composites — no one is proposing crystalline structures for the aerospace industry, or at least not yet. And yet, there is also SAXEM (Sapphire Aluminium oXide and rare Earth Mineral), introduced to watchmaking by none other than — wait for it — Hublot. This new material has fascinating properties (in watchmaking, its startlingly bright colours are unmatched) which have reportedly drawn the interest of the European Space Agency but also muddies the waters for our discussion here. The manufacture calls SAXEM an alloy, which seems to be a bit of a misnomer — we previously called this new material a composite and have sent Hublot a query on the official word. SAXEM is basically what happens when one gets clear corundum, which is its state without impurities, to go wildly colourful with added metals.

Ultimately, how one feels about this corundum conundrum is closely related to how one feels about polymers, composites and other assorted contemporary materials. For example, if one objects to composites and ceramics in watchmaking then does that extend to the sapphire crystal? On the flipside, if one does accept this and the roles of advanced materials in the rest of any given watch, does that mean one has to accept all variations? Yes, Magic Gold comes into it, along with all the other cermet materials and perhaps composites such as carbonised gold. In a way, this illustrates why standard materials are much easier to contend with in watchmaking. 

This article was first published on Issue #69 of World of Watches.

For more reads on watches, click here.