Watch Notes

If your mechanical watch suddenly gains minutes a day instead of seconds, there's a good chance it isn't broken at all: it's magnetized. Phones, laptops and bag clasps are full of magnets. The good news is that magnetism is easy to test for at home and takes seconds to fix. Here's how. Under the balance wheel sits the hairspring, a coil thinner than a hair. Magnetism makes its coils stick together. Photo: Guy Sie , CC BY-SA 2.0 , via Wikimedia Commons. In this guide Why magnetism makes a watch run fast Signs your watch is magnetized The compass test How to demagnetize a watch Common magnet sources to avoid FAQ Why magnetism makes a watch run fast A mechanical watch keeps time with a balance wheel and a hairspring that "breathes" in and out several times a second. Most hairsprings are made of a steel alloy. If they're exposed to a strong magnetic field, the coils become slightly magnetic and cling to each other. The spring then behaves as if it...

Your automatic watch is gaining time, maybe a few seconds a day or several minutes. Before you send it for service, it helps to know what is normal and what is not. In most cases the cause is simple, and in one very common case you can fix it yourself in seconds. An automatic watch's rate depends on its balance wheel and hairspring, the parts most affected by magnetism and shock. Photo: Francis Flinch , CC0, via Wikimedia Commons. In this guide How accurate should it be? How to measure the error Cause 1: Magnetization Cause 2: Resting position Cause 3: Power reserve Causes 4–6: Shock, temperature, service Quick troubleshooting table FAQ First: how accurate should your watch be? Mechanical watches are never as accurate as quartz. Each manufacturer publishes an accuracy tolerance per day: Movement Official tolerance (per day) Seiko NH35 / NH36, 4R35 / 4R36 -20 to +40 seconds Seiko 7S26 -20 to +40 seconds Seiko 6R35 (Prospex, Presage) -15 to +25 seconds Miyota 82...