Troubleshooting

Is my watch magnetized?

If a mechanical watch that kept good time suddenly gains minutes a day, magnetism is the most likely cause. It's common, it's harmless to the watch, and fixing it takes seconds.

What happens

The balance spring, the hair-thin coil that sets a watch's rhythm, is traditionally made of steel alloy. Near a strong magnet its coils can become magnetized and stick to each other. The spring effectively gets shorter, the balance swings faster, and the watch runs fast. Sometimes very fast: gaining several minutes a day is typical.

The signs

• A sudden jump in gain, from seconds a day to minutes a day.
• Erratic timekeeping that changes with position or from day to day.
• Less often, the watch stops and restarts, or loses time.

The compass test

1. Put a compass on a table, away from phones, laptops and metal. A phone compass app works less well because the phone itself is magnetic.
2. Take the watch off and pass it slowly over and around the compass.
3. If the needle swings to follow the watch, some part of it is magnetized.

A small twitch from a steel case or bracelet is normal. A needle that clearly follows the watch around is the giveaway.

How to fix it

Any watchmaker can demagnetize a watch in a few seconds, often for free or a small fee, without opening it. You can also buy a demagnetizer yourself for about the price of a strap. They're small blue or grey boxes: hold the button, bring the watch close, draw it slowly away to a good distance, then release. Test it with the compass again and repeat if needed.

Once demagnetized, the watch should return to its old rate right away. If it doesn't, it needs a proper look; see when to service a watch.

Where the magnets are

Modern life is full of them. The usual culprits:

• Phone speakers and MagSafe chargers, cases and wallets.
• Laptop lids, tablet covers and their keyboard cases.
• Magnetic clasps on handbags, and some jewellery boxes.
• Speakers, headphones and their cases.
• Cheap watch winders with poorly shielded motors.
• Airport and hospital equipment, and induction hobs.

A few centimetres of distance makes a big difference, since a magnet's field falls off quickly. Don't leave a watch resting on a laptop or next to your phone overnight.

Anti-magnetic watches

A watch sold as "anti-magnetic" meets the ISO 764 standard, which is modest protection. Some modern movements go much further by using silicon or non-ferrous balance springs, and several makers now certify watches to 15,000 gauss, which covers anything you'll meet in daily life. Others use a soft-iron inner case to shield the movement.