Understanding Magnetism in Mechanical Watches

Magnetism in mechanical watches is a complex phenomenon that involves the interaction between the magnetic fields present in our environment and the metallic components of the watch. This interaction can cause the watch to run faster or slower, affecting its accuracy.

While magnetism is a natural phenomenon, it can be particularly harmful to mechanical watches. The delicate balance wheel and hairspring, key components in the watch’s movement, are especially susceptible to magnetic fields. When these parts become magnetized, they stick together, causing the watch to run fast.

Magnetic Fields and Their Sources

Magnetic fields are invisible areas of influence that exert a force on materials that are susceptible to magnetism. These fields are produced by the movement of electric charges, such as those found in electric currents and magnetic materials.

In our daily lives, we encounter numerous sources of magnetic fields. These include household appliances, electronic devices, and even the Earth itself. For a luxury mechanical watch wearer, common sources of magnetic fields include smartphones, laptops, speakers, and magnetic closures on bags or jackets.

Effects of Magnetism on Mechanical Watches

The effects of magnetism on mechanical watches can be subtle or drastic, depending on the strength of the magnetic field and the duration of exposure. In most cases, a magnetized watch will run fast, sometimes by several minutes per day. This is because the magnetized components of the watch’s movement stick together, causing the balance wheel to oscillate faster than normal.

In severe cases, magnetism can cause a watch to stop working altogether. This is usually a temporary effect, and the watch will start working again once it is demagnetized. However, prolonged exposure to strong magnetic fields can cause permanent damage to the watch’s movement.

Anti-Magnetic Watches

Given the potential harm that magnetism can cause to mechanical watches, watchmakers have developed various techniques to make their timepieces resistant to magnetic fields. These are known as anti-magnetic watches.

Anti-magnetic watches are designed to minimize the effects of magnetism on the watch’s movement. This is achieved through the use of non-magnetic materials, such as silicon or non-magnetic alloys, in the construction of the watch’s key components. Some anti-magnetic watches also feature a soft iron cage, known as a Faraday cage, that redirects magnetic fields away from the movement.

Materials Used in Anti-Magnetic Watches

The choice of materials is crucial in the design of anti-magnetic watches. Non-magnetic materials, such as silicon, are often used in the construction of the balance wheel and hairspring. Silicon is not only resistant to magnetism, but it also offers excellent shock resistance and temperature stability.

Another common material used in anti-magnetic watches is a non-magnetic alloy known as Nivarox. This alloy, composed of nickel, iron, chromium, and other elements, is highly resistant to magnetism and offers excellent mechanical properties. Other non-magnetic materials used in watchmaking include Glucydur (a beryllium bronze alloy) and Elinvar (an iron-nickel-chromium alloy).

Faraday Cage in Anti-Magnetic Watches

A Faraday cage is a protective shield that redirects magnetic fields away from the watch’s movement. This is achieved by enclosing the movement in a soft iron case, which acts as a conduit for magnetic fields, guiding them around the movement rather than through it.

The effectiveness of a Faraday cage in protecting a watch from magnetism depends on the strength of the magnetic field and the design of the cage. In general, a well-designed Faraday cage can provide excellent protection against everyday magnetic fields. However, it may not be sufficient to protect the watch from extremely strong magnetic fields, such as those produced by MRI machines.

Testing and Certification of Anti-Magnetic Watches

Anti-magnetic watches are subjected to rigorous testing to ensure their resistance to magnetic fields. These tests are typically conducted in accordance with the ISO 764 standard, which specifies the minimum requirements for anti-magnetic watches.

The ISO 764 standard requires that a watch must not stop working when exposed to a direct current magnetic field of 4,800 A/m. The watch must also not deviate by more than 30 seconds per day after exposure to this magnetic field.

Role of the Swiss Federal Institute of Metrology (METAS)

The Swiss Federal Institute of Metrology (METAS) plays a crucial role in the testing and certification of anti-magnetic watches. METAS has developed a stringent certification process that goes beyond the requirements of the ISO 764 standard.

Under the METAS certification process, watches are subjected to magnetic fields of 15,000 gauss, nearly three times the strength specified by the ISO 764 standard. Watches that pass this test are awarded the Master Chronometer certification, which is considered one of the highest accolades in the watchmaking industry.

Notable Anti-Magnetic Watches

Over the years, several watchmakers have produced notable anti-magnetic watches. These timepieces not only offer excellent resistance to magnetism, but they also represent the pinnacle of horological craftsmanship and innovation.

Among the most notable anti-magnetic watches are the Rolex Milgauss, the Omega Seamaster Aqua Terra, and the IWC Ingenieur. These watches are renowned for their superior anti-magnetic properties, as well as their distinctive designs and exceptional craftsmanship.

Rolex Milgauss

The Rolex Milgauss, first introduced in 1956, is one of the most iconic anti-magnetic watches. Designed for scientists and engineers who work in environments with strong magnetic fields, the Milgauss is capable of withstanding magnetic fields of up to 1,000 gauss.

The Milgauss achieves its anti-magnetic properties through the use of a soft iron Faraday cage, which encloses the watch’s movement. The watch also features a unique lightning bolt second hand, a nod to its scientific roots.

Omega Seamaster Aqua Terra

The Omega Seamaster Aqua Terra is another notable anti-magnetic watch. This watch is equipped with Omega’s Co-Axial Master Chronometer movement, which is resistant to magnetic fields of up to 15,000 gauss.

The Seamaster Aqua Terra achieves its anti-magnetic properties through the use of non-magnetic materials, such as silicon, in the construction of its movement. The watch also features a distinctive teak pattern on its dial, inspired by the wooden decks of luxury sailboats.

IWC Ingenieur

The IWC Ingenieur, first introduced in 1955, is renowned for its anti-magnetic properties. The watch was designed for engineers and technicians who work in environments with strong magnetic fields.

The Ingenieur achieves its anti-magnetic properties through the use of a soft iron Faraday cage, which encloses the watch’s movement. The watch also features a simple, functional design, reflecting its technical roots.


Magnetism is a fascinating aspect of luxury mechanical watches, offering a glimpse into the intricate interplay between science and craftsmanship. While magnetism can pose challenges to the accuracy and performance of these timepieces, watchmakers have developed innovative solutions to overcome these challenges.

Through the use of non-magnetic materials and protective shields, as well as rigorous testing and certification processes, watchmakers are able to create timepieces that are not only resistant to magnetism, but also exemplify the highest standards of horological excellence. Whether you’re a scientist, an engineer, or a watch enthusiast, the world of anti-magnetic watches offers a captivating journey into the heart of mechanical watchmaking.


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