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Magnetism – Enemy of Isochronism

by Jordan Ficklin

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First, isochronism is the ability of a watch to maintain constant time independent of the influences around it. Some of the things that affect isochronism include: magnetism, external shocks, friction, and poise of the balance and hairspring. Magnetism is one that you will certainly notice right away.

This week I had a customer’s watch come in that I had serviced about 6 months ago. He said it was losing 15-20 minutes a day. It always makes me nervous when a watch comes back in, but this one was an easy fix. I put it on the timing machine and verified that it was in deed running slow and the amplitude was very low. I didn’t see any immediate issues so I put in on the demagnitizer. — Back on the timing machine: running well again. Magnetism can cause your watch to run fast or slow by even hours a day, I have even seen it bring a watch to a stop.

So, how does your watch become magnetized? If you work around medical equipment it can be a comon occurrence for your watch to become heavily magnetized, but there is a culprit that most of us use that we don’t really think about. You see, all electrical devices produces a small magnetic field. The closer you are to them, the stronger the field. Do you rest your wrists on a laptop when you type? If you do, that could be a cause. Speakers, cell phones, magnets. There are lots of things that can magnetize your watch, unless you get one of these:

Rolex Milgauss

Photo courtesy of

Your watchmaker can take care of the problem without even opening your watch, so if you have noticed a drastic change in your timekeeping, it might just be that electromagnetic enemy: magnetism.

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One Comment

  1. Posted August 2, 2009 at 11:48 am | Permalink

    Perhaps a more precise definition of isochronism is the ability of the balance wheel to maintain the same time interval of its excursion regardless of amplitude.

    A perfectly isochronal balance is impossible, however there have been many improvements over the years in an attempt to alleviate the effects of isochronism.

    The fusee was an early attempt to maintain an even flow of power from the mainspring. The invention of the Breguet hairspring was an effort to alleviate the effects of isochronism. Today’s self-winding watches combat the effects of isochronism, because the mainspring is fully wound through a greater part of the day, and the long run times, fifty hours or more on many modern mechanical movements also contributes to the improvement of isochronal performance.

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