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Opinion: Traditional Artisan’s approach to Hand Finishing and Chronometry

The Common Denominator
by James Tan on June 6, 2017

When watch collectors venture into the realm of high horology, some never really looked beyond aspects like brand recognition, avant-garde-ness or multi-complications of a timepiece. Today, appreciation for hand finishing is still not widely understood by collectors. Granted, high horology does not strictly necessitate hand finishing but the emphasis on craftsmanship has always been a part of traditional watchmaking. Although there are many things a machine can do better than a human (eg. CNC milling), certain finishing work can only be accomplished by a pair of skilled hands. And therein lies the charm of hand finishing – the precious “character” or “emotion” bestowed upon a timepiece through the blood, sweat and tears of an artisan.

As I delved deeper into haute horlogerie, specifically the independent watchmakers, there is something similar that struck me regarding a few interesting individuals’ fundamental approach towards hand finishing and basic chronometry. Perhaps “interesting” is an understatement after all. As a matter of fact, most of them (eg. Philippe Dufour, Kari Voutilainen, Laurent Ferrier, and perhaps Aaron Becsei) are grandmaster watchmakers who produce arguably the most exquisitely hand finished movements on this planet, period. In this article, I would be sharing this common set of, let’s just call it “philosophical modus operandi” (or PMO in short) that I have observed.

Perfectly Polished Convex Bevels

Bevelling (“Anglage” in french), is the process of chamfering the edges of a movement part, especially the bridges. This process was traditionally meant to remove burrs and combat corrosion.



Performed at the highest level, this technique produces clean, consistent, and highly polished convex bevels with no traces of machining marks. A convex bevel (as opposed to a flat bevel) is more difficult and more time consuming to produce, looks more refined and allows light reflection in various kinds of angles.

For delicate or hard to reach areas, the bevelling is meticulously done with a metal hand-file and finished manually with a piece of pegwood (with abrasive paste applied). Otherwise, a bench-style grinding wheel (made of either wood or leather) or a hand-held rotary tool called a “touret” would be used.


Sharp Inward Angles

This is probably the absolute telltale sign that a bevel on a movement is manually hand-finished – sharp inward angles. Because of the tight geometry, no rotary tool is able to properly chamfer and polish a sharp inward bevel without ruining that pointy angle.


Sharp Inward Angles on a Kari Voutilainen Observertoire.


Stroke by stroke, the artisan would use a metal hand-file and pegwood to create a beautifully polished inward angle. A high level of patience and dexterity is required to perfect this technique.


Black Polished Components

Black polishing (“Poli Noir” in french), also called mirror polishing, is the highest standard of polishing technique applied on movement parts (typically on steel surfaces).


Black Polished Escapement Bridge Cap on a Dufour Simplicity.


Interestingly, the finishing only reflects light in a certain angle. At any other angles, the finishing appears black. And hence the name “black” polishing.

This is yet another technique that requires skilled hands and is painfully time consuming. The finishing is done on abrasive surfaces of different grits (eg. emery paper). The artisan polishes the movement part by moving it in a figure-of-eight or a circular motion on the abrasive surface, progressing from coarse to finer grits until a mirror shine is finally achieved. Sounds easy eh? Thing is if the artisan messes up at a grit, he/she would have to go back to the previous grits to start again!

As with all kinds of polishing job, overdoing it will cause substantial shape and material loss, while underplaying it will never get you the desired results.


Use of Overcoil Hairspring

Ever since the very first mechanical watches made, isochronism has always been a challenge in chronometry. Isochronism is the ability to keep accurate time even as the mainspring loses torque while it reaches the tail end of its power delivery. Short of using exotic methods like remontoire or a fusee and chain, a basic way to help in isochronism is via the employment of an overcoil hairspring in the escapement. Named after the inventor, it is often called a Breguet Overcoil.


Overcoil Hairspring on a Bexei Dignitas Pure.


Besides aiding in isochronism, an overcoil hairspring also improves timekeeping by minimising positional variation with its concentric “breathing” motion. This concentric “breathing” is achieved by shaping the outer terminal curve of the hairspring over and above the main coil before terminating it near the centre of the coil.

Despite its merits, there are some reasons why an overcoil hairspring is not so commonly used. Reasons like the addition of thickness to a movement, susceptibility to snagging, and being laborious to produce (an overcoil is bent by hand and subsequently requires careful adjustments). This is why overcoil hairsprings are only used in the higher end models of mainstream HH brands like Vacheron Constantin, Patek Philippe and A. Lange & Sohne.

Use of Free-sprung Balance

In a mechanical escapement, the balance wheel is typically either index-regulated or free-sprung. Instead of having a regulating index that varies the effective length of the hairspring, the free-sprung balance has a fixed-length hairspring and uses variable-inertia screws or weights for timing adjustments. Picture a spinning figure skater – as she pulls her hands/legs nearer to her body, she spins even faster.


Four Eccentric Weights on the Balance Arms of a Raúl Pagès Soberly Onyx.


I remembered during one of the PuristS interview with Philippe Dufour, he described, in his own words, the importance of a free-sprung balance:

“I use a freesprung balance. It’s not just for fun; it’s because I think it’s much better in the long term. Because the regulator pins, everybody knows it gives you problems. You make a nice adjustment today, between the flat and the vertical is nice, fifteen days later, you check it, it is different. Why? That’s why I threw away the regulator pins in my watches.” – Philippe Dufour.


Skin in the Game

After babbling so much about the common PMO from the few Independents, I bet you readers must be wondering if I have my “skin in the game”.


The Author’s A. Lange & Sohne 1815 Chronograph (Ref. 402.032) with the Caliber L951.5. Author’s own photograph.


I’m glad to say I actually dipped my skin into the game. Well, sort of, but it is neither Independent nor Swiss. The timepiece that I have is the A. Lange & Sohne 1815 Chronograph (Ref. 402.032) in pink gold. It may not be from a low production independent watchmaker (sorry to disappoint you Indie fans!), but what the L951.5 movement entails is the same PMO exhibited in the timepieces from the independent watchmakers discussed above.

I have since declared this my “exit” watch, but let’s leave this story for another day. In the meantime, like many WIS-es, I still dream of owning a grail piece from Philippe Dufour. Will I get there? Only time will tell.


Editor’s Note: James Tan posts on his own Instagram account as @Dufourism, and joins Deployant as a contributor with this maiden article. Dufourism. A captivating moniker to those in-the-know. Needless to say, James is a big fan of Dufour. Not the Rolex CEO, but the grandmaster watchmaker Philippe Dufour. Despite his refined taste for hand finished timepieces, he started out humbly like many other watch collectors with a Seiko 5 back in 2007. During his “me time”, he enjoys reading watch blogs as well as meeting and chatting with fellow watch lovers over a cup of coffee. Outside of watches, he is also a sartorial footwear enthusiast who digs dress shoes such as Edward Green, Vass and Crockett & Jones.  

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