How to Demagnetise a Watch

To demagnetise a mechanical watch you pass it over a small electromagnetic demagnetiser, the kind sold for a few thousand naira, and its magnetic field is neutralised in seconds. That is the whole fix. The reason it works, and why a watch runs fast in the first place, is worth understanding so you can keep it from happening again.

• Symptom: a mechanical watch suddenly gains minutes a day.
• Cause: the steel hairspring has been magnetised and its coils cling together.
• Fix: a demagnetiser tool, or a quick visit to any watchmaker.
• Quartz: largely immune. This is a mechanical problem.

What magnetism actually does inside a watch

The regulating organ of a mechanical movement is the balance wheel and its hairspring, a coil of fine steel thinner than a human hair that breathes in and out several times a second. Its length sets the rate. When that steel picks up a magnetic charge, adjacent coils are drawn together and the effective length shortens. A shorter spring beats faster, so the watch gains time, often five, ten, sometimes twenty minutes a day. In bad cases the coils stick fast and the watch stops keeping any sensible time at all.

Nothing is broken. The steel is simply holding a charge it should not have, and removing that charge returns the rate to normal.

How a watch gets magnetised

Everyday objects are the culprits, not industrial machinery. The usual suspects:

• The magnetic clasp on a laptop bag, tablet cover or phone case.
• Speaker magnets, including the ones in a soundbar or a laptop.
• Fridge magnets and magnetic tool holders.
• The magnetic latch on a handbag or a car door pocket.
• Some medical equipment, which is a different order of strength entirely.

You rarely feel it happen. You just notice a watch that kept good time last week is now minutes ahead by lunch.

Confirming it is magnetism and not a service issue

Before you reach for a tool, rule out the obvious. A watch that runs fast is usually magnetised; a watch that runs slow, stops early or has a falling power reserve is more likely asking for a service. If you want certainty, a free smartphone compass app will swing when you bring a magnetised watch close to it. There are also dedicated apps that read the field. If the needle jumps, magnetism is your answer.

Doing it yourself

A blue box demagnetiser is the standard tool and costs very little. The method is simple:

1. Make sure the crown is pushed in and the watch is running.
2. Hold the watch flat against the tool and press the button, or plug it in if it is the always-on type.
3. With the button held, lift the watch slowly and steadily away from the tool, to a good arm's length, before releasing.
4. The slow withdrawal is the important part. It lets the alternating field fade gradually and leaves the steel neutral. Pulling away sharply can leave a residual charge.
5. Check the rate against a reliable clock over the next day.

If one pass does not fully settle it, repeat. There is no harm in demagnetising a watch that is already clean.

When to hand it over

If the rate is still off after demagnetising, the problem was never magnetism, and the watch wants a proper look. Persistent fast or slow running, poor power reserve, or a gritty winding action point to lubrication or wear. Our guide on how often to service a mechanical watch covers the schedule, and the wider habits are in caring for an automatic watch.

Keeping it from coming back

• Do not rest the watch on a speaker or beside a laptop overnight.
• Keep it clear of magnetic bag clasps and phone-case magnets.
• If you own several automatics, mind where the winder sits, as its motor holds a magnet.
• Consider an antimagnetic movement if this keeps happening to you; some carry a soft-iron shield or a silicon hairspring that shrugs magnetism off.

Antimagnetic construction shows up on the spec sheet, and a good movement is worth reading for. Browse the automatic and mechanical collection or the wider shop.

Common questions

Will demagnetising damage my watch?

No. It removes an unwanted charge and touches nothing else. You can safely do it more than once, and there is no downside to demagnetising a watch that turns out to be fine.

Can I use a fridge magnet to fix it?

The opposite. A static magnet magnetises; it does not cure. You need an alternating field that fades out, which is exactly what a demagnetiser produces and a plain magnet cannot.

Are quartz watches affected?

Very little. Quartz timing comes from a vibrating crystal, not a steel hairspring, so magnetism rarely alters the rate. A strong enough field can disturb the stepper motor, but for practical purposes this is a mechanical watch problem.