Irresistible resistibles

Most watch wearers are unaware of the dangers of magnetic radiation to their timepieces and over the years very few watchmakers have offered models with any degree of protection from its effects. Although magnetism is not considered harmful to humans, the chances of exposing our wristwatch to its effects increases annually. While it may seem obvious to expect magnetic radiation to be emitted from complex electric devices and appli-ances, especially personal productivity products containing speakers and magnetic latches, we should take care not to overlook the simplest of magnets we encounter daily – such as those holding the family photos to the refrigerator.

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The humble timepiece has become so much a part of our everyday lives that while we might not always immediately recognise it as such,the wristwatch we rely upon to navigate the hours of our days is a precision instrument. It is an extremely complex device with a mechanical heart beating so precisely and reliably that whenever we require it we can read the time display and be confident in the information we are provided. Magnetism only takes an instant for this unseen force to ruin our watch’s timekeeping, rendering it useless. While the effects can often be removed without dismantling the timepiece by using a process called ‘degaussing’, this needs to be performed by a professional, and service centres around the world report that repairing the effects of magnetism has become one of their largest workloads.

The powerful currents beinggenerated to power a newgeneration of machinery and electric lighting brought with them a by-product of unseen magnetic fields and this was quickly diagnosed as the source of timekeeping problems. The component parts of a watch movement are designed to run asfreely as possible. They are numerous and locat­ed within a tiny footprint, forcing them to live inclose harmony and operate within precise tolerances.

When parts are mag­netised they become attractedto one an­other and rather than run smoothly they attempt to adhere together. Makers of quality timepieces realised early on that it was possible to mitigate some of this issue in the gear train by craftingmove­ment parts from non-ferrousmaterials, as these metals and alloys enjoy antimag­netic properties due to their low iron con­tent. Whilecrafting the movement plates and gear wheels in brass alleviated theis­sue a little, the one part that was always necessary to make of steel was the hair­spring, steel being the only material avail­able from which to produce reliable and long-livedsprings. By the mid 1800s,watchmakers were already hard at work searching for a spring materialthat would not be affect­ed by magnetic fields, successfully exper­imenting with glass, palladium and gold. However, these materials proved too del­icate for prolonged use and the produc­tion of the parts in reasonable quantities was problematical for the technology of the times. It was not until the turn of the century that new alloys were discovered that combined both the flexibility and an­timagnetic properties required, paving the way for the first commercially avail­able ‘antimagnetic’ pocket watch to be launched in 1915.

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During this era, a new watch design was exciting customers: timepieces worn upon the wrist instead of inside a pock­et. The wrist was chosen as it allowed the wearer to check the time ‘hands free’, ex­actly what was needed while trying to control machinery such as early automo­biles and aircraft. However, this location also placed the delicate timepiece in more danger, not only from knocks and wa­ter ingress but also from sources of mag­netic radiation. The issue had become so much of a problem that in 1925 Omega re­leased a wristwatch chronograph proud­ly displaying the term ‘Anti-Magnetique’ on the enamel dial, followed by sever­al more pocket and wrist chronograph watches by the end of the decade. These early timepieces offered improved pro­tection compared to other watches of the day, however the degree of mitigation was limited by the technology available to only low gauss levels.

When the war ended, many of the technological advances began during the hostilities gained traction as civil projects; harnessing nuclearfusion to deliver do­mestic electricity, improving ageing public transpor­tation systems and the developmentof jet engines and rockets. Those working on the infrastructure of these projects often found themselves toiling in workplac­es permeated by ever-more powerfulelectromagnet­ic fields and their watches suffered. With this in mind, Omega began experimenting with a series of new an­timagneticprototype movements with balance wheels manufactured from special metallic alloys that were high in beryllium and protected by Faraday cages. With hair­springs still beingproduced in high iron content steel, the watchmaker’s only defence against magnetic radia­tion was to try to avoid it reaching this delicate part al­together.

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The Faraday cage was achieved by completely surrounding the vulnerable movement with a set of non-ferrouscovers, one behind the movement and another cleverly disguised as the dial. This forced the magneticfield to pass around the covers rather than penetrate and magnetise parts of the movement. In 1953, these prototypes formed the base for a new antimagnetic pilots’ watch to fulfil the new tougher re­quirements of the MoD, and the same year also saw a se­ries of civilian antimagnetic wristwatch prototypes with their dials bearingthe name ‘Railmaster’ loaned to Ca­nadian Railways to take part in a joint yearlong research project to perfect the antimagnetic watch.

The lessons learned from that collaboration led to the launch of the production Railmaster model in 1957, a timepiece aimed squarely at professionals needing an antimagnetic watch for their work. The technology employed endowed these watches with magnetic resistance to around 1,000 gauss, approximately fifteen times greater than a standard wristwatch. This was a critical piece of timepiece inno­vation, important enough that the Railmaster was given equal billing alongside the then brand-new Speedmaster chronograph and Seamaster 300. For the remainder of the twentieth century, Omega continued to produce watches enabled with high levels of magnetic resistance by using Elinvar and Invar alloys for balance springs and Faraday cages within the watch­case construction. However, during the latter decades there was a proliferation in the number and strength of the magnetic sources in the wristwatch’s immediate environment. This was in part due to the explosive up­take of end-user electronics but also to the increased us­age of magnets in everyday objects. Concerned about the limitations in the protection technology available, Ome­ga engineers looked back to where watchmakers start­ed with the problem over one hundred years prior and they focused attention on the creation of a new type of hairspring.

The coiling and uncoiling of this spring oscillates the balance wheel with a known resonant frequency,controlling the speed at which the gears of the timepiece turn. Themore stable this frequency, the greater the precision of the timepiece. When magnetised, the coils of the spring become attractedto one another and the spring cannot fully uncoil. This shortens the effective length of the spring, which has the result of speeding up the timekeeping. In 2008, Omega launched the first Co-Axial movements with a balance springmanufactured from Silicon Si14. While steel springs suffer with variable results during manufacturing and finite life, creating these delicate parts from Silicon Si14 ensures the exact geometry is reproduced every time and remains in specification indefinitely. This space age material uses precise computer-assisted manufacturing processes to perfectly form springs directly from silicon discs in a single step. The result is a component three times finer than a human hair that resists sharp shocks and is completely unaffected by magnetic fields.