The evolution of watchmaking materials is attributed to the original challenges faced in trying to keep accurate time. These include corrosion, temperature expansion and in more modern times, magnetism. These watchmaking materials also needed to be durable, wear-resistant and easily machinable along with other lasting attributes.
Early Beginnings
When watches first appeared in the early 1500s, they were wholly made from iron. Steel, an alloy of iron and carbon, became more common due to its strength and ability to be precisely machined. However, both were prone to rust and required lubrication. Brass, copper-zinc alloy, was corrosion-resistant, and it became widely used in the 1600s to make plates, bridges and gears. Bronze, another corrosion-resistant alloy of copper and tin, was used to make bearings and friction parts. Steel, after hardening and tempering, proved to be more suitable for high-stress components like springs and escapements.
Precious metals like gold and silver came into use for gilding, a decorative technique for applying a very thin coating over metal parts, to prevent corrosion. Platinum was first used to make the staff and pallets of the lever escapement in the watch commissioned for Louis XVI in 1788. However, springs made from such precious metals, including palladium, were not able to sustain consistent timing as they weakened over time.
Further improvements to brass, with nickel, led to the development of nickel silver or maillechort in 1820. Nickel silver replaced brass parts and was also used for plating. Glass was also experimented in 1833 to make balance springs at the time, but faced fragility issues. Synthetic rubies, invented in 1902, led to cheaper jewel bearings for pivots, with reduced friction, wear and tear and no need for oiling.
The Advent of Non-Magnetic Alloys
The ground-breaking invention of Invar in 1895, resolved the issue of inaccuracy caused by thermal expansion in balance springs. Invar, comprising of 36% nickel and 64% iron, has very low coefficient of thermal expansion. Adding chromium to Invar produced Elinvar in 1919, which had additional non-magnetic properties. Elinvar had other combinations like, the ferromagnetic iron-cobalt alloy, the antiferromagnetic manganese-chromium alloy and the non-magnetic palladium alloy. Creation of these alloys led to a boom in watches sporting the antimagnetic description on the dial. Nevertheless, the Tissot Antimagnetique is recognized as the first antimagnetic wrist-watch in 1930, using a palladium alloy balance spring. Further advancements to the Elinvar alloy led to the development of Nivarox for balance springs in 1933.
Separately, in the 1920s, it was found that copper, alloyed with beryllium, gave superior mechanical properties in terms of hardness, resistance to corrosion and low coefficient of thermal expansion. Thus, beryllium-copper alloys replaced steel in springs, balance wheels and hands. A combination of beryllium-copper-iron led to the creation of the Glucydur for balance wheels in 1935. The Glucydur balance wheels and Nivarox balance springs combination brought about a radical change in watchmaking and dominated the industry, for years to come.
Despite the fact that there have been claims of antimagnetic pocket watches from the early 1900s, and the advent of the antimagnetic wrist-watch from the 1930s, they were not truly antimagnetic in todays terms. Then again, the world electricity generation in 1930 was a mere 66 TWh compared to the 29,165 TWh in 2022. The magnetic field intensity back then was just a fraction, less than 1%, of what it is today.
The Soft Iron Shield
It was not until 1948, that a soft iron shield was used to enclose a movement, allowing the magnetic field to flow around the enclosure without affecting the movement. IWC and JLC, both developed the Mark 11, as specified by the British RAF. This gives Mark 11 the distinction of being the first truly antimagnetic watch. An example of soft-iron is Mu-metal, developed in 1923, it is a soft alloy with high magnetic permeability. It consists of mainly nickel, up to 80%, and 15% iron, with the balance being any combination between copper, chromium, molybdenum or silicon.
Though, the soft iron enclosure may resemble the Faraday Cage in construction, it does not serve the same purpose as the Faraday Cage, neither is it a Faraday Cage. A Faraday Cage blocks electromagnetic fields, not magnetic fields, while the soft iron allows the magnetic field to flow around it. Thus, it is surprising to see certain watch manufactures continue to refer the soft iron shield to the Faraday Cage in their descriptions.
The 1950s was a boom for antimagnetic watches using the soft iron shield, with many produced until the 1960s. The quartz crisis of the 1970s and 1980s slowed down the mechanical watchmaking industry almost to a halt. The 1980s was a time for quartz watches and plastic components brought on by the precision of plastic injection molding machines.
New Age Materials
Mechanical watches made a come back in the 1990s, and saw the use of titanium for rotor and bridges, offering strength with reduced weight while ceramics and carbon-fiber parts provided durability, wear-resistance and shock absorption. The 2000s brought on innovations like Rolex’s Parachrom hairspring made from niobium-zirconium alloy, which have paramagnetic properties. In 2016, H.Moser & Cie presented a new niobium-titanium alloy; PE500, which is paramagnetic and shock resistant while Swatch also came up with their own titanium-based Nivachron in 2019 featuring paramagnetic properties. Paramagnetic materials are weakly attracted by magnetic fields but do not retain any magnetism once the field is removed.
Technological advances in plasma etching led to silicon escape wheels, balance and levers. Silicon outperforms other alloys in almost all other aspects except in shock-resistance due to its brittle nature. Ulysse Nardin was the first to market with the silicon hairspring in the Freak in 2001. Patek Philippe introduced Spiromax in 2006, followed by Breguet, with Omega releasing Si14 in 2008. Rolex unveiled the Syloxi in 2014, while Baume & Mercier joined the party with Twinspir in 2017. In between, Cartier launched Zerodur, a glass ceramic composite material in 2009.
Recent years saw further advancements in carbon technology leading to the development of carbon-composite hairsprings. In 2017, Zenith launched their carbon-matrix carbon nanotube balance spring while Tag Heuer followed suit with Isograph in 2018. Carbon-composite has been tested to be far more durable than silicon-based hairsprings, able to withstand g-forces of up to 5G.
These new age materials have successfully addressed magnetism. Though it will take some time, but eventually, all watches produced hereafter, will be inherently antimagnetic.
