Magnetism: What You Don't Know
We hear the term ‘Magnetism’
Thrown around frequently as something the wreaks havoc on timing. With no shortage of magnetic surfaces and scanners, it’s not uncommon for your wrist watch to get magnetized in shipment or throughout the course of the day. Though, what does this actually mean?
When enthusiasts and hobbyists talk about magnetism they are, 99% of the time, talking about magnetized hairsprings. What happens when a hairspring becomes magnetized? Its shape changes, sometimes it can stick to itself, this shortens its effective length and makes it run erratically fast - or sometimes stops it altogether.
What if I told you this presentation of magnetism, while valid and real, is actually the less common form of magnetism? What if I told you magnetism can drain amplitude and maybe make your watch run slower, or marginally (not very) faster?
That’s right. Magnetism in watches is perhaps one of the most common ailments in poor timekeeping but enthusiasts rarely expect it because the only aspect of it that has been glorified is the magnetism of the hairspring and erratic and crazy fast rates that accompany it.
Once I had people tell me these guys were not magnetic.
What really happens when your watch is magnetized?
Your watch has a handful of magnetic components. Ignoring new silicon escapements/hairsprings that are impervious to pedestrian Gauss levels, your watch has steel pinions and pivots (the parts that the brass wheels in the gear train are friction fitted onto), a steel pallet fork, escape wheel, screws, and a few other components. It’s generally not a huge deal having some magnetized screws, but when the pinions and your pallet fork/escape wheel become magnetized, you’re in for a doozy. In this scenario, your hairspring can be absolutely fine but your gear train will be magnetic. Your pallet fork will be sticking to your balance and escape wheel, not lifting off freely and draining amplitude.
What is amplitude?
Amplitude is the degrees of rotation of the balance wheel. This indicates how much power is going through your gear train. If your watch is fully wound, but has low amplitude it can mean it’s dirty, something is obstructing it, or perhaps it is magnetized. Without getting too crazy into hairspring dynamics and horology, a steady beat rate at high amplitude will yield better timekeeping. So if your amplitude is not stable and is low, you will experience poor timekeeping. And in this case, magnetism is causing the steel components of your gear train to attract and ‘stick’ which is reducing their freedom and creating drag, which in turn is reducing amplitude and affecting your watches ability to keep good time - but in this scenario it may be slow or it may be +20 or +30 and not the +20 minutes a day people talk about with a magnetized hairspring.
So what can you do?
Buy a demagnetizer. The cheap ones aren’t great, and for watchmaking equipment I never recommend the bottom tier equipment, but they’re still cheaper than shipping a watch around or taking a day to visit a jeweler/watchmaker. There are two types of demags, the kind that deliver a constant ‘stream’ and then the instantaneous pulse type. I’d recommend watching some tutorials on technique but for the kind that delivers the stream (where holding the button keeps the power on) you start with your watch or parts close to the machine, turn it on, slowly pull the watch away while holding the demag on. Once you’ve reached your arms limit, turn it off. You can repeat a second time. For the pulse type; hold your watch over the machine, activate it, then rotate your watch 90º and activate it again. You may want to hack (stop) your watch while demagnetizing it.
