The History of the Mainspring

The mainspring’s origins can be traced back to the 15th century, a time when mechanical clocks were transitioning from weight-driven mechanisms to spring-driven ones. This shift was a significant milestone in horology, the study of timekeeping, as it allowed for the creation of portable timekeeping devices – the precursors to the modern wristwatch.

The earliest mainsprings were made of iron and were wound by hand using a key. Over the centuries, as watchmaking techniques evolved and materials improved, the mainspring underwent numerous refinements. Today, mainsprings are typically made of a special alloy known as ‘Nivaflex’, which is resistant to corrosion and has excellent elastic properties.

The Evolution of the Mainspring

The development of the mainspring has been driven by the pursuit of greater accuracy and reliability in timekeeping. Early mainsprings had a major drawback: as the spring unwound, its force would decrease, leading to a loss of accuracy. This problem, known as ‘power reserve depletion’, was a major challenge for early watchmakers.

In the 17th century, the invention of the fusee, a cone-shaped pulley, helped to equalize the force of the mainspring as it unwound. This was a significant advancement, but it added complexity to the watch’s movement and was not a perfect solution. It wasn’t until the 20th century, with the development of the ‘self-compensating’ mainspring, that this issue was largely overcome.

The Design of the Mainspring

The mainspring is a marvel of design and engineering. It is a long, thin strip of metal, coiled tightly into a spiral. One end of the spring is attached to the barrel arbor, while the other end is hooked onto the inside of the barrel wall. When the watch is wound, the spring coils tighter, storing energy. As it unwinds, this energy is released, driving the watch’s movement.

The design of the mainspring must strike a delicate balance. It must be strong enough to store sufficient energy, yet flexible enough to wind and unwind without breaking. The length, width, and thickness of the spring, as well as the material it is made from, all play a crucial role in achieving this balance.

The Material of the Mainspring

The material used for the mainspring has a significant impact on its performance. Early mainsprings were made from iron or steel, but these materials were prone to rust and lacked the necessary elasticity. Today, most mainsprings are made from a special alloy known as ‘Nivaflex’, which has excellent anti-corrosion properties and superior elasticity.

Nivaflex is a cobalt-nickel alloy, with traces of beryllium and other elements. This alloy is not only highly resistant to corrosion, but also has a very high yield strength, meaning it can be wound tightly without deforming. This allows for a high energy storage capacity, contributing to the watch’s power reserve.

The Role of the Mainspring in a Watch’s Movement

The mainspring plays a crucial role in a watch’s movement. It is the source of all the energy that drives the watch. When the watch is wound, either manually or automatically, the mainspring is coiled tighter, storing energy. As the spring unwinds, this energy is released in a controlled manner, driving the gears and wheels that move the watch’s hands.

The energy from the mainspring is transmitted through the gear train, a series of gears that amplify the spring’s force. The escapement then regulates the release of this energy, ensuring that the watch ticks at a consistent rate. This precise control of energy is what allows a mechanical watch to keep accurate time.

The Power Reserve

The power reserve of a watch is a measure of how long the watch can run on a single winding of the mainspring. This is an important aspect of a watch’s performance, as it determines how often the watch needs to be wound. The power reserve can vary greatly between different watches, depending on the design of the mainspring and the efficiency of the movement.

Most mechanical watches have a power reserve of between 36 and 48 hours, although some high-end models can run for several days or even weeks on a single winding. The power reserve is often indicated on the watch’s dial, allowing the wearer to see at a glance how much energy is left in the mainspring.

The Challenges of Crafting and Maintaining a Mainspring

Crafting a mainspring is a complex process that requires a high degree of skill and precision. The spring must be made to exacting specifications, with a uniform thickness and a smooth, flawless surface. Any imperfections can affect the spring’s performance, leading to inaccuracies in timekeeping.

Maintaining a mainspring is also a challenge. Over time, the spring can become worn or damaged, affecting its ability to store and release energy. Regular servicing is necessary to ensure the mainspring remains in optimal condition. This typically involves disassembling the watch, cleaning and inspecting the mainspring, and replacing it if necessary.

The Craftsmanship Involved

The crafting of a mainspring is a testament to the skill and artistry of the watchmaker. It involves shaping a thin strip of metal into a precise spiral, a process that requires a steady hand and a keen eye for detail. The spring must be wound tightly, but not so tight that it risks breaking. This is a delicate balance that takes years of experience to master.

Once the spring is formed, it is carefully installed in the watch’s movement. This is a delicate process, as the spring must be handled gently to avoid damaging it. The spring is then tested to ensure it is functioning correctly, with any necessary adjustments made before the watch is reassembled.


The mainspring is a vital component of a mechanical watch, playing a crucial role in the timepiece’s operation. Its design and function are a testament to the skill and precision of watchmaking, a craft that has been honed over centuries. By understanding the mainspring, we can gain a deeper appreciation for the artistry and engineering that goes into every luxury mechanical watch.

From its humble beginnings in the 15th century to the sophisticated designs of today, the mainspring has evolved alongside the watch itself, reflecting the advancements in materials and techniques. It is a testament to the relentless pursuit of accuracy and reliability in timekeeping, a quest that continues to drive the world of luxury mechanical watches today.


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