Long the focus of military watches, dive watches and other models aimed at a technically minded customer, more watch companies today note their ability to resist magnetic fields.
When Omega last year demonstrated its most technically advanced anti-magnetic movement, the Omega Co-Axial calibre 8508, several of the technicians presenting the movement reminded the assembled audience about modern magnets. Omega Vice President and Head of Product Development Jean-Claude Monachon told the attendees at the New York press conference that today’s consumer-product magnets are not only more powerful than they have been in the past, but that these magnets are also more present in our daily lives.
Think about your briefcase (or pocketbook); it is far more likely today to feature a magnetic clasp. Consider also your iPad, mobile phone case and even jewelry–all frequently equipped with new, strong magnets. In addition, the many new electronic devices we carry around today also generate their own magnetic fields, adding many more potential sources. Indeed, retailers and service centers are known to keep desktop de-magnetizers handy to address those customers with magnetized watch problems.
Just as watchmakers and service centers have to deal with the issue of magnetism, consumers too should be aware of the negative affect magnetic fields can have on mechanical watch precision, Monachon added. If the balance or other oscillating component inside the movement becomes magnetized, it will typically result in accelerated timekeeping, which is typically the first hint that something is amiss inside the movement. Greater exposure, or even cumulative exposure, can stop the movement in its tracks.
Ironies
Of course watchmakers have long struggled with the elements, so to speak, with iron being the most problematic. Easily magnetized, iron historically was among the elements needed to make hairsprings (the others being nickel, and cobalt and chrome-based metals). Even in the 19th century many companies touted their own methods for avoiding iron in balance springs (and in other components) in order to create so-called anti-magnetic pocket watches. Watchmakers tried special anti-magnetic alloys and protection “cages” that isolated the calibers, keeping magnetism at bay with varying degrees of success.
After Charles Edouard Guillaume invented Elinvar in 1896, however, watchmakers had a more powerfully antimagnetic ally. As one of the first anti-magnetic alloys suitable for widespread use in timepieces, Elinvar, and twenty years later Invar (also invented by Guillaume) spurred more anti-magnetic options for watchmakers. By the 1950s alloys like Nivarox and Glucydur, even more resistant to magnetism, began to dominate hairspring production, where they interacted with a full array of non-magnetic components throughout the movement itself.
In the past century, many companies have created specially built anti-magnetic watches that combined new alloys and protective cages. These include companies like Vacheron Constantin, IWC, Jaeger-LeCoultre, Tissot, Rolex and Omega, each of which pioneered anti-magnetic watchmaking in their own respective niches.
Current models
Yet, despite all the new alloys, magnetism can still affect balance springs and other moving parts inside most mechanical watches sold. And as Omega’s Monachon notes, we carry around sources of magnetism every day.
This is why a number of prominent companies create specific models with added anti-magnetic features. Long the focus (and requirement) of military watches, dive watches and other models aimed at a technically minded customer, more companies today note their ability to resist magnetic fields. Soft iron cages that surround movements in many of these models assure that magnetism won’t reach the balance or other components inside. Others tout even newer, totally non-magnetic springs and component alloys.
Today, the international standard (ISO standard 764) for any watch that wants to be known as truly antimagnetic dictates that the watch must continue to run with a deviation of no more than thirty seconds per day within a magnetic field of 4,800 A/m (amperes per meter). Given that many household magnets today create levels beyond this figure, a watch meeting this standard might still be seen as vulnerable to many owners. In addition, no watch meeting only this minimum standard would qualify as a chronometer. Thus, anti-magnetic watchmaking tactics today aim for much higher resistance to magnetic fields.
On these pages we’ve gathered numerous models with serious anti-magnetic properties. Many boast decades of testing and research specifically aimed to create anti-magnetic models (IWC, Vacheron Constantin, Omega, Sinn and Tissot) while others feature silicon or other non-metallic balance springs that tout anti-magnetic properties. Many offer tested anti-magnetic properties to provide shielding for at least up to a strength of 40,000 A/m, well above the ISO minimum standard.
While Omega’s new Caliber appears to lead the field in terms of tested resistance (tested to 15,000 gauss or about 1.2 million A/m—well beyond the 80,000A/m or 1,000 gauss cited by others) these models will surely protect your timepiece from that too-attractive refrigerator magnet.
