If you own a mechanical watch, you need to be aware that magnetism can affect its accuracy. Mobile phones, microwaves and certain electrical instruments can have an effect on the accuracy of a mechanical timepiece, depending on the proximity and duration of exposure. Additionally, certain medical testing equipment can have an adverse effect, which is why patients are often advised to leave their watch at home or in a locker during testing.
Of course, there are watches on the market that are designed to be anti-magnetic. Essentially, an anti-magnetic watch can run with minimal deviation in time tracking when exposed to magnetic fields. The International Organization for Standardization has issued a standard for magnetic resistant watches: ISO 764 Horology - Magnetic. It states that a watch must keep its accuracy to +/- 30 seconds a day to be magnetic resistant.
Among the ways certain brands build anti-magnetic watches include building movement components using alloys that are insensitive to magnetism. Such alloys include Glucydur, Nivarox and Elinvar — which you will find in some of the finest sport and dress watches in the world. They have been used for more than half a century for different parts. Today, many brands are also using alloys for their mainsprings and hair spring, which also helps.
Additionally, some brands avoid the magnetism issue by housing the movement in a soft iron (or similar material) case. This is especially true of pilot watches and sport watches. It should be noted the magnetic fields we encounter day to day are typically not strong enough to do damage to your mechanical watch. If you have a job where you are continually exposed to magnetic fields, stop in and talk to us about the right watch for your wrist that is anti-magnetic and still suits your needs.