Composite

In watchmaking, the term composite doesn't describe a single material but rather an entire construction logic: two or more materials that are naturally incompatible are joined permanently to achieve properties that neither possesses alone. From my bench, I've watched this approach become systematic over the Nineties, and today it's the playing field where much of the technical research by the great manufacturers unfolds.

The most widespread family is carbon fiber-based. Forged carbon—also called forged carbon—is produced by cutting filaments into short segments, arranging them randomly inside a mold, then compressing everything under heat with epoxy resin. The result is a material roughly five times lighter than stainless steel and significantly more impact-resistant than laminated sheet carbon; the irregular marbled pattern is a direct consequence of the process, not an aesthetic choice added afterward. Variants like the Carbonium from Ulysse Nardin and Romain Gauthier use aerospace-grade fibers with specific resins, while Lavoisier Composites' Nylo-Foil replaces part of virgin carbon with nylon recycled from fishing nets and carbon fiber recovered from racing hulls.

The second important family is ceramic-metallic composites. IWC's Ceratanium joins titanium and ceramics through a sintering process that maintains titanium's lightness while adding the surface hardness of ceramics. The Ultra-Cermet used by Parmigiani Fleurier works with different proportions—roughly 40% titanium in a ceramic matrix—and achieves a hardness of 1450 Vickers. Rado's Ceramos, instead, is based on titanium carbide at around 90%, achieving metallic luster with the scratch resistance of technical ceramics.

There are also composites that integrate precious metals: Bulgari's CarbonGold, introduced as early as 1993 and revisited in the Octo Finissimo, combines rose gold with carbon fiber to reduce density while maintaining the metal's value. Chronoswiss' Titanium Core Nano Shell, instead, works in layers: a grade 5 titanium core is permanently bonded to a colored composite shell through active bonding, so that the color is a structural part of the material rather than a finish.

Less frequent but technically interesting is forged quartz fiber: the process mirrors forged carbon, but the quartz base guarantees superior UV resistance and allows deep coloration. Richard Mille's Thin Ply Technology—abbreviated TPT—takes this principle to extremes, laminating ultrathin layers oriented with precision before polymerization.

A note on HealTech: it's a surface self-healing technology applied to carbon that, when heated between 100 and 150 °C, closes micro-imperfections. It comes from the aerospace sector; in watchmaking it's still more of a promise than an established practice, at least from what I've seen to this day.