Demagnetization (Entmagnetisierung)
A service procedure that removes residual magnetic charge from a mechanical watch movement. Magnetised movements run several minutes per day fast. The fix is fast and inexpensive but often misdiagnosed as "broken watch".
Demagnetization (German Entmagnetisierung) is a service procedure that removes residual magnetic charge from a mechanical watch movement. It is the most common "the watch is running fast" complaint a watchmaker receives and the fastest, cheapest fix in watch servicing.
Why watches magnetise
Modern environments are full of magnetic fields strong enough to magnetise a steel-component movement:
- Smartphones and tablets with embedded magnets for stands and accessories.
- Laptop hinges with magnetic latches.
- Magnetic bag closures and wallet clasps.
- Induction cooktops.
- Speakers and headphones.
- MRI medical procedures (very strong; usually requires deep service after).
When a steel hairspring becomes magnetised, adjacent coils stick to each other, shortening the effective hairspring length and accelerating the rate. The watch can run anywhere from +30 seconds to +5 minutes per day depending on the strength of the magnetisation.
How demagnetization works
A demagnetiser is a simple electromagnet that produces an alternating magnetic field. The watch is placed on or near the device, a button is pressed, and the field cycles down to zero — leaving the movement's steel components with no residual magnetisation.
The whole procedure takes under one minute. It can be performed without opening the case. The cost at a watchmaker is typically €10 to €30 (often included free if the watch is being serviced anyway).
When to suspect magnetisation
- The watch suddenly runs much faster than its previous rate, despite no other change.
- The watch was wound or stored near a known magnetic source.
- Quartz movements are largely immune (the timing is crystal-based) but can show stopped-second-hand symptoms if magnetisation affects the stepper motor.
Confirmation is straightforward: a watchmaker passes the watch over a magnetic indicator (an app on phone, or a dedicated tool). A strong reading confirms magnetisation as the cause.
Why dealers should care
For a pre-owned watch being acquired, magnetisation is the cheapest cause of "the rate is off" findings on a timegrapher. Demagnetising before regulation testing avoids over-treating a magnetised but otherwise healthy movement.
Several modern designs are increasingly resistant:
- Rolex Parachrom hairspring (modern, paramagnetic alloy) — significantly resistant.
- Omega Si14 silicon hairspring — non-magnetic.
- Master Chronometer certified Omega watches — tested to 15,000 gauss resistance.
- Tudor's Master Chronometer line (introduced 2021).
For dealers, knowing which references are inherently magnetic-resistant helps explain return-question patterns and informs whether magnetisation is the likely cause of a rate complaint.
Related: regulation, master-chronometer, cosc, manufaktur-service.