Hairsprings: The Invisible Component That Makes or Breaks Accuracy
The Heart of the Watch
Inside every mechanical movement, the balance wheel oscillates back and forth at a fixed rate. The component that controls this oscillation — and therefore the watch's accuracy — is the hairspring.
What a Hairspring Is
A hairspring (also called balance spring) is an ultra-thin spiral of metal alloy attached to the balance wheel. As the balance swings, the hairspring coils and uncoils, providing the restoring force that brings the balance back to center. Think of it as the pendulum's equivalent in a watch — but coiled flat instead of hanging free.
How It Affects Accuracy
The hairspring's natural frequency determines how fast the balance oscillates. A shorter effective length = faster oscillation = watch gains time. A longer effective length = slower oscillation = watch loses time. Regulation adjusts this effective length.
Modern Hairspring Materials
- Nivarox: nickel-iron alloy with titanium — the industry standard for decades. Affordable, reliable, slightly magnetic
- Parachrom (Rolex): niobium-zirconium alloy — 10x more shock-resistant than Nivarox, non-magnetic
- Silicon: etched from single silicon wafers — perfectly non-magnetic, no lubrication needed at the impulse pin, but fragile under extreme shock
- Spiromax (Patek): silicon-based with optimized geometry for consistent rate across positions
The Trade-Offs
| Material | Magnetic Resistance | Shock Resistance | Cost |
|---|---|---|---|
| Nivarox | Moderate | Good | Low |
| Parachrom | Excellent | Excellent | High |
| Silicon | Perfect | Moderate | Premium |
Frequently Asked Questions
Can a hairspring be repaired?
Bent hairsprings can sometimes be straightened by a skilled watchmaker. Tangled or broken ones must be replaced.
Does silicon mean no servicing?
No — silicon hairsprings still require cleaning and lubrication of other movement parts.
What do our watches use?
The NH35 family uses Nivarox-type hairsprings — proven, reliable, serviceable worldwide.