Is your mechanical watch suddenly running wrong, possibly faster than usual, even though it hasn’t been subjected to heavy impacts or other jolts? And this despite the fact that it was recently serviced – or is perhaps even new? Search the internet for the reasons, and the possibility of watch magnetization will almost certainly come up in this case. Due to the magnetization surrounding us in some places, many watches are designed with a special or even complete magnetic resistance, and advertised as “anti-magnetic.” What exactly is behind this terminology?
Magnetism
Every child knows what a magnet is. A magnet can be used to attract or repel objects made of certain materials. A magnet generates a magnetic field in its environment, which in turn interacts with other bodies made of certain materials – this is the magnetism phenomenon. There are different types of magnetism: diamagnetism, paramagnetism, and ferromagnetism are of particular interest when it comes to watches. Diamagnetic materials such as zinc or copper are repelled by an external magnetic field when they are exposed to it. Both paramagnetic and ferromagnetic substances are attracted to a magnetic field. Put simply, the main difference is that this effect is much less pronounced with paramagnetic materials, and that there is no permanent magnetization, as is the case with ferromagnetic materials. It’s this effect that causes problems for watches.
Magnetization can be imagined like this: In a ferromagnetic material in the normal case, i.e. in the non-magnetized state, there are numerous chaotically ordered areas of differently oriented magnetization. When viewed macroscopically, these tiny areas, which occur across mere nanometers, result in non-magnetic behavior due to their statistical distribution. This changes when this kind of substance or a component of such a substance comes into contact with a magnet and its magnetic field. The wildly distributed areas align themselves according to this magnetic field and remain in this state even if the magnet and magnetic field are removed from the area. The result is a magnetized component, which in turn now acts as a magnet and can influence other components with a magnetic field.
How is a watch magnetized, and what are the consequences?
In order for components of a watch to be magnetized, they must be exposed to a magnetic field. This field can emanate not only from magnets, such as those used on fastening bags, wallets, or tools, but also from electromagnetic fields stemming from electronic devices. Electronic devices in particular are becoming more and more prevalent in our everyday lives, with the actual impact on a watch depending heavily on the type of device giving off the magnetic field, and its distance from the watch.
Whatever the source of the magnetic field, if a watch has been exposed to it, it may be permanently magnetized. Although various ferromagnetic, mostly ferrous components can be found in a watch, the negative effects of magnetization mainly affect the heart of the watch: the balance wheel of the movement. In the past, balance wheels were made of steel, which made them not only temperature-sensitive but also susceptible to magnetism. The invention of temperature-insensitive materials such as Nivarox in 1919 not only largely solved the temperature problem of watch sensitivity, but also massively reduced the influence of magnetic fields on them. Although Nivarox and comparable alloys for balance wheels are almost entirely antimagnetic and also fulfill certain standards that justify this nomenclature, they actually are not 100% antimagnetic. If balance wheels are magnetized, oscillation is impacted, thus throwing off the accuracy of the watch. In extreme cases, coils of the spring can even stick against each other. The result is a typical symptom of magnetization: the watch runs too fast, in some cases minutes a day. In fact, magnetization can also lead to a lag, even though other reasons for this deficiency are also possible.
What can be done to prevent the magnetization of watches?
A watch can be protected against magnetization by the manufacturer and the wearer. In the simplest case, as the wearer you have a watch that is designed to be so anti-magnetic that no influences in everyday life can cause magnetization. If this is not the case, or if the magnetic field protection of your watch is only moderate, and it’s been exposed to a very strong magnetic field, magnetization is likely. In general, it is always a good idea to first check whether magnetization is the cause of any sudden deviations in the rate of a watch. Fortunately, this can be done not only by any watchmaker, but also by really any jeweler. Simple devices can also be purchased very cheaply for home use. These are very easy to use: just place the watch on them, press a button, and slowly remove the watch. The magnetized areas are transferred from their aligned state back to the chaotic, macroscopically non-magnetic state.
Watch manufacturers have two main options for making watches (almost completely) anti-magnetic: The first is to house the movement in a so-called soft iron case. Soft iron has so-called soft magnetic properties, it has a low remanence, which means that magnetization does not persist after removal of an external magnetic field. The soft iron cage as the outer case of the movement is a historically tried-and-tested method, even though it tends to make a watch relatively thick, and does not allow for glass case backs. Modern watches are increasingly solving the problem of magnetism by using particularly non-magnetic materials for the hairspring. Examples include silicon, as well as the Parachrom alloy from Rolex, which is based on niobium and zirconium.
Three Popular Anti-magnetic Watches
1. Seamaster Aqua Terra > 15,000 Gauss
In 2013, Omega launched this variant of the Seamaster Aqua Terra with the less-than-memorable reference 231.10.42.21.01.002, which was advertised as the world’s first “completely” anti-magnetic watch. Gauss is the unit of magnetic flux density, and 15,000 is the value that this watch with its 8508 movement can withstand. This level is also tested during the METAS test this timepiece undergoes. The main reason for this is the silicon hairspring – a material that Omega continues to use to this day.
2. Rolex Milgauss
The Rolex Milgauss, discontinued in 2023, itself bears the reference to the Gauss unit in its name. Its original model from the 1950s used a construction with a soft iron cage. When the Milgauss returned in 2007, it featured the particularly antimagnetic Parachrom Rolex hairspring.
3. IWC Ingenieur Automatic 40
The current iteration of the IWC Ingenieur, the Ingenieur Automatic 40, like its original 1950s model also relies on the tried-and-tested solution of an anti-magnetic soft iron inner case. This means that you have to do without a glass case back, which IWC – unlike Rolex – typically likes to use.
