A. Lange & Söhne

as a dedicated Lange fan and collector i always want the brand to be the best it could be as their successes and achievements become a source of pride for me. One of the things that bothered me a lot was the fact that the gorgeous Saxonia Moonphase central rotor is, in fact, not made of solid gold- this is the case with every Saxonia model with a rotor- with very little information as to why. Clearly the first thought to come to mind is Lange is cutting costs to widen their profit margin. 

This SIHH2019 i had the opportunity to speak to Anthony De Haas, the Director of Product Development at Lange, and ask why the rotor is not gold. The answer i got made lots of sense and reinforced my belief in the brand. The reason gold was not chosen was their desire to keep the watch as slim as possible with the most efficient rotor to wind the power reserve- gold is elastic too and prone to impacts by shocks. Therefore another solution was found. The metal chosen is a base metal that addresses thickness and elasticity with better resistance to shocks.

The amount of gold in a rotor is really insignificant in terms of costs and the decision to not use gold was entirely technical, also there is a platinum mass on the outer edge to make the winding even more efficient.

Hope this answers the question for some of you whom i spoke with regarding this topic. 

"Regarding the rotor in the new self-winding movement: The motivation for the replacement of the 21k rotor with one gold plated is not an exercise in cost saving, otherwise probably the platinum would have been substituted as well. And as has been pointed out, the amount of gold used is so small, the cost differential with the base metal used is inconsequential.

[It] is due to the need for rigidity. Gold, especially 21k gold used in the original Langematics are very soft, and when used in a very thin arrangement like they are for the new Automatic as well as for the Daymatic, it is prone to being stretched when large forces are applied to it. The watch experiences these large forces everytime you move your hand swiftly. Plus, Herr Schlenker at the lab does a hammer test with 5000 G (I have shown pictures of this test before) and with a malleable metal like 21k gold, it would be forced out of shape and render the rotor useless. Hence a more rigid and physically stable metal needed to be used.

In the Lange 1 Daymatic the inner part was copper-beryllium, then there was a gold segment, and outside the platinum weight. Already here copper-beryllium has been used for better stability and stiffness in relation to the big size of the central rotor.

The rotor in the new Saxonia self-winding caliber is even thinner and there is less space (or height) for screwing and connecting the segments. And it was decided to use ARCAP for technical reasons. ARCAP is an alloy very close to German silver (only 2% difference within the ingredients)."