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Roger Dubuis - The Twofold Mystery

Roger Dubuis The Twofold Mystery

Uncovering the secrets of the new Roger Dubuis Excalibur Twofold.

Two weeks ago, Roger Dubuis announced the first of their new 2020 timepieces. The Excalibur Twofold made a high-impact landing with its introduction of a new material used in watchmaking — Mineral Composite Fibre, which you’re allowed to call MCF if you’re one of the cool kids. (You will be, by the time you finish reading this article.)

MCF is a bright white synthetic material that extremely light and machinable, setting it apart from white ceramic — which is much more challenging to form into complex shapes. MCF is very similar in composition to the high-tech materials that protected NASA space shuttles from burning up during the re-entry sequence.

Excalibur Twofold

Excalibur Twofold © Roger Dubuis

The basic building block of the MCF material is silica. That’s right, as in silicon dioxide, which we know in its crystalline form as quartz. In this case, the silica comes in amorphous (non-crystalline) form, and is shaped into short fibers with an average length of 0.64mm and diameter of between 1.2–1.4 microns. These fibres are put through a hydrocyclone process and centrifugal extractor to purify and compact them into a solid mass of evenly distributed fibers. This is where I start using words like material isotropy, which is usually a reliable method to help even highly-stressed people overcome insomnia, so I’ll cut to the chase. All you need to know is that, to the naked eye, the individual silica fibres are indistinguishable from each other and the mass appears to be a highly dense, bright white foam. 

This foam is then injected with a special white epoxy resin, characterised by specific properties such as UV resistance and chemical non-reactivity. Roger Dubuis worked closely with a specialist partner to arrive at this particular epoxy resin that would meet all their needs. Heat and pressure are applied to the foam and epoxy resin, distributing the epoxy resin homogenously throughout the matrix microstructure of the silica foam. The resulting material, MCF, can then be machined like any other conventional watchmaking material. Even the white dial-frame, with the extremely fine arms of the emblematic Roger Dubuis star and the tourbillon apertures, can be made in MCF with significantly less risk of fracture than comes with a material such as white ceramic. 

Excalibur Twofold

© Roger Dubuis

 One downside to MCF is that it is unable to hold different finishes, such as mirror polish or satin brushing, which is why Roger Dubuis has made subtle changes to the design of the case to create visual distinctions between the different angles and facets. They are working on a way to apply different finishing techniques to MCF, however, so don’t be surprised to see further developments in this area in the future.

The Excalibur Twofold comes with a bright white rubber strap, which hides another innovation. Turn off the lights and you will see that luminous lines are visible along the length of the strap. This is a new type of rubber composite, impregnated with luminous material. It is not an applied coating — the rubber itself glows in the dark. It’s called LumiSuperBiwiNova. Yes, it’s really called that. No further comment. To create the effect of the luminous pattern, two types of rubber, one luminous and one non-luminous, are used in the specific design of the Excalibur Twofold strap. The non-luminous rubber is then ablated to bring out the luminous rubber sections. 

Excalibur Twofold

Calibre RD01SQ © Roger Dubuis

Congratulations, you’ve made it to the end of this article and you are now a technical cool kid! The information above was derived from a combination of mercilessly browbeating Roger Dubuis technical director Gregory Bruttin with questions and digging up research papers on Lockheed Martin material innovations, a process that I (and Greg) devoutly hope never takes place again. However, knowing the penchant that Roger Dubuis has for fascinating high-tech materials — you guys remember the Excalibur Quatuor in silicon and the other one in Cobalt Micromelt? — it’s probably going to happen again.

One last question remains: Why is the Excalibur Twofold called the Twofold? I didn’t ask — because life is more interesting when there are one or two mysteries left in it.


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The Roger Dubuis Manufacture was founded on the desire for independence and watchmaking excellence. With remarkable dynamism, Roger Dubuis quickly ignited the world of Haute Horlogerie and has developed over thirty completely original in-house movements. Striking a fine balance between traditional watchmaking expertise and avant‑garde design, the Manufacture became a specialist in architectural skeletonised movements.

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