Introduction
Magnetic fields are everywhere - from your phone speakers to laptop covers, airport scanners, and even magnetic clasps on bags. While harmless to most modern electronics, magnetic fields pose a serious threat to mechanical watches. Magnetism can disrupt a watch’s accuracy, stop it altogether, or even cause permanent damage if not handled correctly.
Antimagnetic watches are engineered to solve this problem. But what makes a watch antimagnetic? How did watchmakers first realize this issue, and how have they tackled it over time? In this article, we’ll explore the evolution of antimagnetic technology, the science behind magnetic interference, and how today’s watch brands protect their mechanical marvels from invisible forces.
The Early Encounters with Magnetism
Before the 20th century, magnetism wasn’t considered a major threat to watches. Everyday life didn’t involve strong magnetic fields. But as technology progressed - especially with the rise of electrical infrastructure and industrial equipment - magnetism became a silent enemy to timekeeping accuracy.
Railroad workers and military personnel were among the first to report problems. Their watches, exposed to telegraph lines, engines, and radio equipment, began running fast or stopping entirely. The problem wasn't mechanical failure, but magnetic interference.
One of the earliest documented responses came in 1896 when Vacheron Constantin experimented with antimagnetic materials. However, it was Rolex that truly brought the issue into the spotlight decades later.
What Magnetism Does to a Mechanical Watch
To understand the threat, let’s break down how a traditional mechanical watch works.
At the heart of a watch is the balance wheel and hairspring. The hairspring (also called a balance spring) is a delicate, coiled wire that helps regulate the oscillation of the balance wheel. This oscillation is what keeps the time consistent.
The hairspring must maintain a precise shape and tension to function properly. When exposed to a magnetic field, the hairspring can become magnetized - which means its coils start sticking together. When that happens, the spring contracts, increasing the rate of oscillation and causing the watch to run fast - sometimes gaining minutes per hour.
In more extreme cases, other steel components in the movement can become magnetized too, creating erratic behavior or complete failure.
Worse still, magnetization doesn’t just disappear when the watch leaves the field. A watch can remain magnetized until it’s demagnetized using a special device.
A Growing Problem in Modern Life
Today, we are surrounded by magnets - more so than ever. Smartphones, tablets, laptops, speakers, microwave doors, and even magnetic charging cables can emit enough magnetic field to throw off a watch. While these aren’t industrial-strength magnets, close and prolonged exposure is enough to cause harm.
The problem is particularly annoying because it’s invisible. Your watch may seem fine, only to begin gaining 5-10 minutes a day after a weekend trip or a new gadget on your desk.
This has led to a new wave of innovation from watchmakers - using non-magnetic materials and clever design to protect their movements without sacrificing transparency, thinness, or cost.
Antimagnetic Materials in Watchmaking
To combat magnetism, watchmakers began experimenting with alternative materials - especially for the most sensitive components, such as the hairspring, balance wheel, and escapement.
Early Solutions: Soft Iron Shields
The first major defense was soft iron inner cases, forming a protective cage around the movement. Soft iron doesn’t block magnetic fields but redirects them around sensitive components - much like a Faraday cage. This was the core strategy behind early antimagnetic watches such as the Rolex Milgauss
| Store | Link |
|---|---|
| Ebay | Buy on Ebay |
and IWC Ingenieur.
| Store | Link |
|---|---|
| Ebay | Buy on Ebay |
| The Luxury Closet | Buy on The Luxury Closet |
Soft iron shielding worked well, but had limitations. It added bulk and made features like transparent casebacks impossible. This led to innovations in material science.
Modern Materials: Silicon and Beyond
One of the biggest breakthroughs in recent decades is silicon. Non-magnetic and highly temperature-resistant, silicon components - especially silicon hairsprings - have become a game-changer in the fight against magnetism.
- Silicon hairsprings are lightweight, perfectly uniform, and unaffected by magnetic fields.
- Amagnetic alloys such as Glucydur (beryllium bronze), Nivarox, or Parachrom have also become common in high-end and mid-range models.
By replacing ferromagnetic parts with these materials, some modern watches no longer need traditional shielding - they’re inherently immune to magnetism.
International Standards: How Antimagnetic is “Antimagnetic”?
Not all antimagnetic watches are created equal. To make sense of the differences, several standards define what counts as antimagnetic - based on how much magnetic field a watch can withstand while staying accurate.
ISO 764: The Benchmark
The ISO 764 standard defines a watch as antimagnetic if it can resist a magnetic field of 60 gauss (4,800 A/m) and still maintain an accuracy deviation of less than ±30 seconds per day.
While useful, this level is modest by today’s standards - many watches now go far beyond it.
Advanced Resistance: 1,000 Gauss and Up
- Rolex set a new standard in 1956 with the Milgauss - named for its resistance to 1,000 gauss (80,000 A/m). This was a big leap, especially for professionals in scientific and industrial fields.
- Today, brands like Omega, IWC, and Grand Seiko have models that withstand magnetic fields of 15,000 gauss and beyond.
Omega, in particular, introduced the Master Chronometer certification in partnership with METAS (Swiss Federal Institute of Metrology), testing watches against 15,000 gauss and evaluating water resistance, accuracy, and performance under real-life conditions.
Notable Antimagnetic Watch Models
Let’s look at some of the most iconic and technically impressive antimagnetic watches in history - both past and present.
Rolex Milgauss
- Introduced: 1956
- Magnetic resistance: 1,000 gauss
- Key features: Soft iron shield, lightning bolt seconds hand, scientific legacy
- Notable model: Ref. 116400GV with green sapphire crystal
Designed for scientists at CERN, the Milgauss remains a cult classic. While Rolex discontinued the model in 2023, its legacy lives on in the antimagnetic field.
Omega Seamaster Aqua Terra >15,000 Gauss
- Introduced: 2013
- Magnetic resistance: Over 15,000 gauss
- Key features: Silicon balance spring, non-ferrous parts, transparent caseback
This model marked a revolution. Instead of shielding the movement, Omega built one that’s virtually immune to magnetism - even with an open caseback. It led to the brand’s METAS Master Chronometer movement line.
IWC Ingenieur
- Introduced: 1955
- Magnetic resistance: Early models: ~80,000 A/m
- Key features: Soft iron inner case, tool-watch design, Genta redesign in the 1970s
Originally developed for engineers and technicians, the Ingenieur was one of the first purpose-built antimagnetic watches. Modern versions balance industrial strength with luxury styling.
Grand Seiko SBGA231 and SBGR317
- Magnetic resistance: Up to 4,800 A/m
- Key features: Magnetic-resistant cases, precision Spring Drive movements
While not extreme in magnetic resistance, Grand Seiko’s models balance precision, elegance, and a respectable level of shielding for daily wear.
Sinn 857 UTC and Other Tool Watches
- Magnetic resistance: Often 80,000 A/m or more
- Key features: Soft iron shielding, hardened cases, functionality-first design
Sinn specializes in functional tool watches. Many of its pilot and diving models meet or exceed traditional antimagnetic standards.
Looking Ahead
Magnetism is here to stay - and so are mechanical watches. Fortunately, advancements in materials and design mean you don’t have to choose between the two. Whether you’re a field engineer, scientist, or just someone who keeps their phone a bit too close to their wrist, there’s an antimagnetic watch for you.
How to Detect Magnetization, Prevention Tips, and Demagnetizing Tools
Magnetism can silently sabotage a mechanical watch. It doesn’t break anything, but it throws off precision - sometimes severely. This part of the guide will show you how to recognize the signs of a magnetized watch, how to protect it from magnetic fields, and what tools can help you fix the issue at home.
Signs Your Watch Might Be Magnetized
Most mechanical watches today operate within a range of -20 to +20 seconds per day (depending on quality). If your watch suddenly starts gaining 5–10 minutes a day, or stops entirely, magnetism could be the cause.
Here are common symptoms:
- Watch running too fast - A magnetized hairspring can coil too tightly, making the balance wheel oscillate faster.
- Inconsistent timing – Magnetization often leads to erratic timekeeping.
- Watch stops and starts randomly - Some components may be stuck or misaligned due to magnetic pull.
- Compass test reaction - Hold your watch near a simple magnetic compass. If the needle moves wildly, your watch is likely magnetized.
Note that these issues can also be caused by shock, dirt, or lubrication problems - but magnetism is one of the most frequent culprits.
Common Sources of Magnetic Fields
You don’t need to visit a physics lab to get magnetized. Everyday objects are surprisingly strong sources of magnetic interference.
Here are some examples:
- Smartphone and tablet cases with magnets
- Laptop speakers and wireless chargers
- Magnetic purse clasps
- Induction cooktops
- MRI machines or airport security scanners
- Headphones or home audio systems
Even brief contact with a magnetic field can be enough to affect delicate watch parts - especially if the balance spring is made from older, ferrous metals.
How to Prevent Magnetization
Preventing magnetization is easier than dealing with it afterward. Here are practical tips to protect your watch:
1. Be aware of your environment
Avoid resting your watch on laptops, phone cases with magnetic clasps, or near speakers.
2. Use watch storage with shielding
Some watch boxes or rolls include anti-magnetic linings. This can help when traveling.
3. Wear antimagnetic watches
If you work in a high-field environment (lab techs, sound engineers, etc.), opt for a model certified to ISO 764 or similar.
4. Store mechanical watches away from electronics
Nightstands with wireless chargers, for example, can be a silent threat if you leave your watch next to them overnight.
How to Demagnetize a Watch
If you suspect magnetization, there’s no need to panic. Demagnetizing a mechanical watch is straightforward and doesn’t harm the movement. You can take it to a professional - or do it yourself using an inexpensive tool.
Option 1: At a watchmaker’s shop
Most professionals have a desktop demagnetizer and can fix the issue in under a minute. If your watch is still under warranty or high value, this might be your best bet.
Option 2: Buy a demagnetizer
There are affordable demagnetizers available online, typically for $10–$50. They’re small, safe, and easy to use.
| Store | Link |
|---|---|
| Amazon | Buy on Amazon |
Here’s how it works:
- Place the watch on the demagnetizer.
- Press and hold the button.
- Slowly move the watch away from the device in a straight line.
- Release the button and turn off the device.
What’s happening here? The alternating magnetic field created by the device randomizes magnetic orientation in the steel parts, effectively "canceling out" residual magnetism.
Option 3: Professional-grade tools
Brands like Bergeon offer professional tools used by watchmakers. These are more expensive ($100+) but are built to last for years.
Bonus: Smartphone Apps for Testing
Several iOS and Android apps allow you to check for magnetism using your phone’s magnetic sensor. They aren’t perfectly accurate, but they can help identify obvious problems. Apps like Lepsi Watch Scope and Lepsi Watch Tester are popular among enthusiasts.
Final Thoughts
Magnetism is one of the few invisible enemies of mechanical watches - silent, unpredictable, but completely preventable. The good news is that modern watches, especially antimagnetic models, are more resilient than ever.
Understanding how to detect magnetization, avoid strong fields, and demagnetize when necessary ensures your watch keeps ticking accurately. Whether you own a basic ETA-based tool watch or a luxury Omega with a Co-Axial movement, a few simple precautions go a long way.
In the end, it’s not just about performance. It’s about preserving the soul of your mechanical timepiece - the balance wheel, hairspring, and escapement that make it come alive.