For more than three centuries, the humble hairspring has been the beating heart of the mechanical watch. This delicate spiral of metal governs the oscillations of the balance wheel, and in turn, the accuracy of the entire timepiece. From Christiaan Huygens’ first use of a balance spring in the 17th century to the Breguet overcoil refinements of the 18th, the hairspring has been the site of incremental innovation, yet for most of its history remained fundamentally the same: a strip of finely tempered steel or later, specialized alloys like Nivarox.
In the late 20th and early 21st century, however, a new material arrived to shake the very foundations of horology: silicon. What started as an experimental project has evolved into one of the most significant advances in mechanical watchmaking since the lever escapement. Today, silicon hairsprings are embraced by high horology maisons, mainstream luxury brands, and even independent makers. But what exactly makes silicon such a game-changer — and what are the debates surrounding its use?
Before silicon, most hairsprings were made from metallic alloys, particularly Nivarox, an iron-nickel-chromium alloy introduced in the 1930s. Nivarox hairsprings offered impressive resistance to temperature changes and magnetism compared to earlier blued steel versions, but they were not without limitations.
Magnetism: Everyday magnetic fields — from smartphones, laptops, or even handbag clasps — can magnetize steel alloys. A magnetized hairspring coils onto itself, shortening its effective length, and wreaking havoc on accuracy.
Temperature sensitivity: Though alloys like Nivarox compensated well, temperature fluctuations still introduced slight timing variations.
Manufacturing limits: Traditional hairsprings are drawn from metal wire, a process that leaves microscopic inconsistencies. Even tiny imperfections in thickness or elasticity can create isochronism errors (the ability of the hairspring to maintain consistent timing regardless of amplitude).
For centuries, watchmakers compensated with design tweaks: overcoils, special alloys, temperature-compensating balance wheels. But the root problem — the material itself — remained.
Silicon (technically silicon monocrystal) possesses a suite of properties almost tailor-made for horology:
Non-magnetic: Silicon is immune to magnetism, eliminating one of the greatest enemies of precision timekeeping.
Thermally stable: Its coefficient of thermal expansion is extremely low, meaning it barely changes dimensions with temperature shifts.
Elastic memory: Silicon bends and flexes with remarkable precision and returns exactly to its original form, ensuring near-perfect isochronism.
Lightweight: A lighter hairspring means reduced energy demands, improving efficiency.
No lubrication needed: Silicon components have almost no friction at a microscopic level, reducing wear.
Moreover, silicon can be fabricated using Deep Reactive Ion Etching (DRIE), a microelectromechanical systems (MEMS) process borrowed from the semiconductor industry. This allows hairsprings to be etched with micron-level precision, guaranteeing consistency impossible with drawn metal wire.
The story of silicon in watchmaking begins around the year 2000, when a research consortium of Patek Philippe, Rolex, and the Swatch Group partnered with the Centre Suisse d’Electronique et de Microtechnique (CSEM) to explore micromechanical applications.
2001: Ulysse Nardin unveiled the Freak, the first production watch to use silicon escapement components. Its radical carousel movement showcased the material’s potential.
2006: Patek Philippe introduced the Spiromax hairspring, made of silicon with a patented geometry that improved isochronism without needing a Breguet overcoil.
2008: Breguet presented its silicon balance spring in the Classique 5197. Swatch Group subsequently rolled out silicon hairsprings to Omega, Blancpain, and other brands.
2014 onwards: Omega made silicon hairsprings standard in its Master Chronometer calibers, marketing their anti-magnetism up to 15,000 gauss as a major consumer benefit.
Today, silicon hairsprings are widespread across the industry, from entry-luxury (Tissot and Longines offer models with them) to haute horlogerie. Independent brands like Kari Voutilainen and Laurent Ferrier have also adopted silicon for specific models.
One of the greatest benefits of silicon is not just the material itself, but what it allows in design. Traditional metallic hairsprings required an overcoil to ensure concentric “breathing” during oscillation. Silicon, by contrast, can be etched with a perfectly optimized terminal curve directly into its geometry. This eliminates the need for overcoils, freeing up vertical space and simplifying assembly.
Furthermore, because the geometry is computer-designed, watchmakers can experiment with new spring shapes impossible in metal, fine-tuning performance to levels previously unthinkable.
Despite its advantages, silicon is not without controversy in the watch world. Critics raise several concerns:
Fragility: Silicon is not ductile. Whereas a steel hairspring can be manipulated, bent, or repaired by a skilled watchmaker, silicon is brittle and can shatter under stress.
Repairability: This brittleness leads to a bigger philosophical problem — silicon components cannot be reshaped or repaired in a traditional workshop. If a hairspring is damaged, it must be replaced, and only the brand (with access to specialized fabrication facilities) can provide one.
Industrial dependence: Unlike metal hairsprings that independent watchmakers can source or even produce, silicon springs require clean-room MEMS fabrication. This ties watchmakers to large corporations and limits independence.
Tradition vs. technology: Some purists argue that silicon undermines the artisanal nature of horology. After all, watchmaking historically celebrated the ability of human hands to coax precision from humble metals. Silicon feels more like a product of the semiconductor lab than the watchmaker’s bench.
The debate over silicon ultimately reflects two visions of horology.
Progressive vision: For many brands, silicon is a triumph — a way to make mechanical watches genuinely more accurate, more robust against daily life, and less reliant on fragile human adjustments. It demonstrates that mechanical watchmaking, even in the age of quartz and smartwatches, can still innovate.
Traditionalist vision: For others, silicon is antithetical to the romance of horology. The hairspring has always been a site of handcraft and adjustment. By replacing it with an industrially fabricated chip-like part, something essential to the art is lost.
Interestingly, some brands straddle both camps. Patek Philippe, for example, uses silicon hairsprings in many calibers but insists on positioning them as part of a long tradition of refinement rather than a rupture from the past.
Where does silicon go from here? Several possibilities stand out:
Wider adoption: As fabrication costs fall, silicon hairsprings may become standard even in affordable mechanical watches.
Hybrid materials: Some researchers are exploring silicon coated with diamond or silicon-oxide composites, further enhancing durability.
Customization: MEMS fabrication could allow brands to create bespoke spring geometries tailored to different calibers, potentially pushing chronometry closer to perfection.
Repair ecosystems: The industry may eventually develop more accessible ways for independent watchmakers to handle silicon components, balancing tradition with modernity.
The silicon hairspring is more than just another incremental improvement — it represents a fundamental shift in how watchmakers think about the beating heart of the mechanical watch. By eliminating magnetism, improving thermal stability, and offering unprecedented precision, silicon has already proven itself as a worthy successor to metal alloys.
And yet, the debates surrounding it remind us that horology is not just about performance metrics. Watches are cultural objects, blending science, craft, and emotion. Silicon may be the future, but its acceptance will always depend on how well it can coexist with the romance of tradition.
In that tension lies the beauty of horology today: a field that can honor the artisanal past while embracing the technological future — one oscillation at a time.