Close up of a CNC machine used in movement finishing
Any watchmaker worth his salt will tell you that there is no such thing as an unimportant or less important component. And that’s why we have finishing processes like anglage (or chamfering in English), which is mainly used for movement components that are more than likely kept unseen, like the bridge and pinions.
As hinted by the name, this technique involves beveling to smooth the edges of a component and create a 45-degree angle. While this can be done by machine, interior angles are commonly done by hand. Saying that this is a difficult process would be an understatement as the smoothness, width and polish of the edges have to be absolutely consistent across every component. So, while it’s mostly hidden, anglage is a mark of quality for top-tier movements.
The name of this finishing technique is the French word for “pearling,” and is easily recognized by its shape: Small, overlapping circular patterns. Perlage is most often employed on a watch’s top and base plates.
While it may sound simple, achieving a mirror finish on a movement component is an arduous process. The component is polished repeatedly using diamond paste, starting with a coarse grain and gradually moving to increasingly finer grains. The absolute best mirror finish that can be achieved is known as black polish. Besides being totally smooth and unblemished, the surface will also appear pitch black when viewed from certain angles as it absorbs all light hitting it. Alternatively, when viewed from the opposite angle, its reflection will be intense and un-diffused.
As such, the mirror finish often becomes the most visible and easily recognizable type of finish, and is often employed to draw the eye toward parts that are supposed to be noticeable like the bridges of a tourbillon or the hammers of a minute repeater.
Breguet’s Héritage Grande Date 5410 sporting multiple guilloche techniques on the dial
The Finish Line
Of course, there are many more procedures meant to elevate the polish and smoothness of movement parts, including supplementary smoothing on miscellaneous parts that are not subject to one of the treatments above (called brouillage), circular or linear graining to create a matte effect and so on and so forth.
The ones we did cover, however, give us a glimpse at one of the most refined aspects of watchmaking—one that turns mechanical components into stunning works of art, even if it is only the watchmaker himself who will ever see it. If the sight of a tourbillon or the chime of a minute repeater represents the ingenuity of watchmaking, then movement or dial finishing represents the commitment of the world’s best watchmakers to their art.
A sketch of Bulgari Octo Finissimo Minute Repeater’s movement with notes on the finishing techniques used
This article first appeared on DA MAN Caliber 2016. Get the magazine here
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