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The invisible enemy of watches: magnetism
A watch can survive rain, cold and shock. But when it comes to magnets, its Achilles heel is called the spiral of the pendulum. Upon contact with a magnetic field, the turns stick together, the frequency goes wrong, and the watch suddenly begins to move forward several minutes per day. The irony is beautiful: it is not the high mountains that threaten your minutes the most, but the bag with magnetic clasp, the portable speaker or the back of a smartphone.
Hence this question, very contemporary and yet a century old: why are some watches antimagnetic? Because they were designed to win a discreet battle that our daily lives continue to intensify.
From rails to the lab era: the genesis of an obsession
At the start of the 20th century, the electrification of the world revolutionized watchmaking. Power stations, transformers and telegraphy magnetize professional watches. The watchmakers react: Tissot Antimagnetic (1930s) marks the democratization of the concept; Vacheron Constantin experiments with non-ferromagnetic alloys on pocket watches; the railways, demanding, pushed manufacturers to innovate.
In the 1950s, science accelerated. Engineers, doctors and physicists work among powerful equipment. IWC launchesEngineer (1955), Rolex responds with the Milgauss (1956) designed for laboratories, Omega presents the Railmaster (1957). The legend is in progress: antimagnetism is becoming a true field of watchmaking excellence, with a vocabulary, solutions and icons.
1) The soft iron shield
The historical method consists of enclosing the movement in an internal soft iron casing (often wrongly called a “Faraday cage”). This material attracts the field lines and deflects them around the mechanical core. The dial, the casing ring and the back form a continuous shield.
- Advantages: robust protection, stable over time, ideal for professional use.
- Compromise: full back rather than a sapphire back; slight increase in thickness.
2) Non-magnetic materials
The modern way neutralizes the problem at the source: remove sensitive components. Silicon spirals (Si14 at Omega, Syloxi at Rolex), paramagnetic alloys (Parachrom type), non-ferromagnetic lever and escape wheel, optimized bridges and axes. Result: even without a soft iron cage, the watch resists much higher fields.
- Advantages: high resistance, transparent background possible, reduced weight.
- Compromise: advanced technology, complex manufacturing, maintenance to be entrusted to certified workshops.
How much gauss is “sufficiently” antimagnetic?
The standards provide a floor. ISO 764 (and its DIN equivalent) requires a “magnetism-resistant” watch to withstand 4,800 A/m, approximately 60 gauss, without excessive drift. It was respectable yesterday; it’s modest today. Rolex popularized the idea of the “thousand gauss” (1,000 gauss) in the 1950s, IWC made it an engineering signature, and Omega set the bar very high with its Master Chronometer certifications tested at 15,000 gauss (1.5 tesla), i.e. fields encountered near MRIs and industrial magnets.
On the other hand, real life is not a magnetic tunnel. It is made of repeated micro-exposures: magnetic clasps, tablet cases, bags, speakers, chargers and accessories with integrated magnets. Individually, these sources do not rival an MRI; cumulative and too close, they are enough to disrupt an unprotected hairspring.
Signs, reflexes and maintenance: what to do if your watch is racing?
Recognizing a magnetized watch
- Sudden gain of several minutes per day, sometimes from the first hours.
- Absence of prior shock or marked temperature variation.
- Erratic behavior: significant advance during the day, better at night (far from magnets).
The cure
- Demagnetization: a watchmaker carries it out in a few seconds with a dedicated device. It is painless and often spectacular.
- Prevention: avoid placing the watch on a speaker, a magnetic charger or a magnetic cover. A simple distance of a few centimeters already reduces the risk.
- Upgrade: if you live surrounded by magnets (sound studio, lab, MagSafe gadgets), a watch with a silicon spiral or soft iron shielding brings real peace of mind.
The major antimagnetics to know
- Rolex Milgauss (1956): designed for laboratories, famous for its lightning second hand and its 1,000 gauss protection.
- IWC Ingenieur (1955): the “engineering tool” approach par excellence, soft iron cage and technical design.
- Omega Railmaster (1957) then Master Chronometer: from railway tradition to the 15,000 gauss of the METAS era.
- Patek Philippe Amagnetic ref. 3417 (late 1950s): rare, sober, cult for purists.
- Jaeger-LeCoultre Geophysic (1958): born for the International Geophysical Year, designed for scientists.
- Tissot Antimagnetique (1930s): one of the pioneers of mass-produced antimagnetism.
What do they have in common? A technical response to a real risk, combined with an immediately identifiable style. Antimagnetism is not a gimmick; it is an aesthetic and functional grammar which tells of an era: that of rails, of particle accelerators, then of our connected lives.
Is an antimagnetic watch necessary today?
If you wear a mechanical on a daily basis, the answer is happily yes — if only for peace of mind. A “standard” resistance protects against small exposures, but a silicon hairspring or an armored construction erases the majority of modern hazards without sacrificing the pleasure of the sapphire caseback (in the case of material solutions).
Keep a simple idea in mind: waterproof, shockproof, anti-magnetism. The triptych of the true everyday watch. The first protects you from the elements, the second from accidents, the third from the invisible enemy. And he is perhaps the most omnipresent today.
As a moral
There is nothing more romantic than a pendulum that breathes in its own rhythm. Antimagnetism is the promise that this breath remains true, despite the magnets scattered in our pockets. A promise born on the rails, matured in the labs, and become the best ally of everyday elegance.
