The Breitling Watch Source Forums

So Nivarox is non-magnetic because it contains little iron. Instead it is mostly cobalt, chromium, and nickel. This is an obvious improvement over steel as it is less affected by magnetism.

So what does Rolex's Parachom bring to the table? Does it simply have a higher tensile strength, or are the materials used in its construction unique? I am interested to see what improvements Rolex has made to the hairspring.

OK, well let's be careful about wording before we start. To be non magnetic you need a hairspring that has no ferrous metals in it at all and that realistically means silicon or parachrom. All of the others are magnetic resistant, they can still be magnetised if you try hard enough - stick them in an MRI machine and the rate will be affected. Additionally, these alloys were designed to be less reactive to heat - less expansion and contraction affecting the rate.

Elinvar was the first major step forward from steel and that appeared around 1920 but that was still more than 50% iron. Nivarox came along in the 30s and reduced the iron content to about 5%. Parachrom was the first mass market hairspring to completely eliminate iron - i.e. to be non-magnetic and that appeared in 2000. Nowadays Rolex are movingto the next generation - blue parachrom which is an oxide coated version of the original. It's not just because it looks better, it supposedly makes the parachrom even more stable / less reactive to heat.

Metallurgically the two are vastly different - parachrom is mostly niobium (>80%) with the rest zirconium, nivarox is almost 50% cobalt with chromium, nickel, iron, titanium and beryllium.

That's interesting considering that both niobium and zirconium are paramagnetic. They must have been chosen for their low thermal expansion. I guess there is a trade off with every metal that can be used.

A few years ago, Patek came up with a silicone hairspring that was cast in a mold. Really cool! I don't know how much it got integrated into their line.

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