Watchmaking is an art form.
Everything from a watch’s case layout and sizing to dial execution and proportionality affects the way a timepiece looks and presents to others. As one moves up the food chain in the watchmaking space, however, more and more emphasis is placed on movements. Indeed, the best watchmakers create movements that are both extremely accurate and aesthetically beautiful.
While affordable watches are often viewed more for their service as accessories or tools, the movement finishing on a piece of haute horlogerie must truly be exceptional. And though one can often find even inexpensive watches with excellent dials, quality becomes instantly obvious when comparing movements side by side.
In order to truly appreciate fine movement finishing, one needs to understand what one is looking at. Today, we’re listing some of the most common watch movement finishing techniques and explaining their importance. This should help you make more informed purchasing decisions as well as appreciate the nuance that goes into crafting an exceptional timepiece.
Anglage visible on bridge components of a Lange movement.
Much of fine finishing is about contrast — placing polished components next to brushed ones, adding dimensionality, casting shadow lines alongside bright surfaces, etc. These choices are made to help accentuate the shape and definition of movement components and make the movement “pop.” One way watchmakers do this is with anglage, meaning “beveling” in French. At the edge of a bridge component, watchmakers have the choice of how to address sharp edges. Rather than leave these bridges with corners, one will typically see a 45-degree bevel. On high-end watches, this is achieved by using a file to first define the profile, and then progressively apply finer and finer abrasives to bring this anglage to a mirror shine. One will often hear collectors describe “mirror anglage,” which is simply a fancy way of denoting highly polished bevels on the edges of bridges. The tops of bridges are usually left with a lower-polish, coarser finish, which means that the anglage helps to accentuate the shape of the movement components through added contrast and three-dimensionality.
Anglage on a Romain Gauthier caliber - (Image by Romain Guathier)
Different watchmakers will approach anglage differently. Typically, the more expensive the watch, the higher the polish on the bevels and the more hand-work is associated with the finishing. On mass-produced watches, mechanized rotary tools are often used to abrade the bevels onto the surface and fewer fine abrasives are used. Furthermore, watchmakers like Philippe Dufour and Romain Gauthier, who are universally lauded as being some of the greatest movement finishers, create much more pronounced anglage, with thicker bevels brought to even higher levels of polish. (It’s also important to note that independent watchmakers of this kind will apply anglage to internal corners, something that is incredibly difficult to achieve and is typically avoided on lower-end models.)
Perlage on an A. Lange & Söhne Datograph Perpetual Calendar Moonphase - IN THE SHOP
Perlage actually plays both an aesthetic and a utilitarian role in the movement. Small circular graining, typically applied to the baseplate — essentially the “motherboard” of watch movements upon which all other components are set — perlage helps to interrupt the angular lines of a movement, adding curvature and shape. Compared to anglage, perlage is a coarser finish which is never polished to a mirror shine — but this is actually intentional. In addition to its aesthetic advantages, the coarse, microscopic grooves perlage abraded into the surface help to capture tiny bits of dust that wind up in a movement during assembly. This ensures that the dust is trapped and doesn't interfere with the function of the movement. (This is actually the origin of the technique.)
On the highest-end watches, perlage is hand-applied with a wet sanding abrasive and a small wooden rod. This process is incredibly labor intensive, and most modern manufacturers will opt for modern rotary tools with abrasive pads to streamline the process — including, ironically, certain brands operating in the haute horlogerie space, such as Patek Philippe. Smaller, independent operations are where power tools are relegated to the sidelands and greater emphasis is placed on hand-work.
Black Polish/ Mirror Polish
Black mirror polishing on an A. Lange & Söhne 31 - IN THE SHOP
Perhaps the most difficult finish to execute is black polish. We previously mentioned mirror anglage, which requires using a succession of abrasives until a mirror shine is achieved. Now imagine that rather than a small bevel, an entire surface receives this finish — that’s the idea behind black polish. In order to understand the finish, one needs to first understand that every polish, no matter how fine, is an abrasion. From coarse to fine, polishing materials are removing small amounts of material. The grooves in the surface of a material get progressively smaller and smaller until they aren’t visible to the naked eye.
Let’s say a watchmaker begins with a 400-grit abrasive. They then progress to 600-grit and must remove all the 400-grit scratches that remain before they can progress to, say, 1000-grit. A black-polished surface is often achieved in the neighborhood of 20,000-grit. This means that it takes a considerable amount of time to work through the grits and slowly remove the old scratches that remain as the polish becomes more and more elevated. A black- or mirror-polished surface is flawlessly brought to a reflective shine that appears almost black in the light. It’s a brilliant surface finish that, like anglage, is typically placed alongside a brushed element for contrast.
Lange will often use black polish on the tops of screw heads or for their swan’s neck regulators. Black polish is also incredibly common on the bridge supports of tourbillons and other exposed components. Grand Seiko uses a similar finish with machine tools to achieve the legendary “Zaratsu” polish. This is another finish that is exceedingly difficult to replicate on lower-end watches, and thus, one doesn’t typically see black polish appear until one is examining watches on the high end of the watchmaking spectrum.
Striping on an A. Lange & Söhne Lange 1 movement - IN THE SHOP
Another incredibly common finish is striping. Geneva striping — or côtes de Genève — is by far the most common way of describing the technique, although in Germany, brands like Lange use “Glashutte striping”, which refers to the same general technique. The principle in all cases is the same: to create a set of vertical stripes with engraved grooving on the surface. Once again, like perlage, striping plays both an aesthetic and a practical purpose. Likewise, once again, the goal is to trap small dust particles rather than letting them interfere with the operation of the movement.
Unlike certain other finishes, côtes de Genève can be easily replicated on lower-end watches. On premium movements, the effect is typically achieved with a lathe, but on mass-produced movements, companies will establish elaborate CNC processes to achieve the same finish. (There is certainly a brilliance to hand-applied striping that is lacking on lower-end movements, but it is there nonetheless.) Some makers go the extra mile, using this stirping as another form of artistic expression. Take De Bethune, for example, who place Geneva stripes on the surface of their dials, but flip the dial halfway through the process so that the engraving is always angled towards the center on either side. On most watches, all the stripes flow in the same direction — having both sets of stripes point inwards creates a mirror effect that is distinct and beautiful.
Blued screws visible in an A. Lange & Söhne Cabaret movement - IN THE SHOP
If you were to open up a vintage, high-end pocket watch, you’d see that the screws are likely blued. Many modern manufacturers have carried the same practice forward, although once again, on lower-end watches, significant differences emerge. Originally, blued screws had nothing to do with color. Watchmakers would heat treat screws to increase the hardness of the steel components. Then, to ensure that the metal doesn’t become brittle, they would temper these screws. This would turn the screw head blue. Depending on the temperature at which the tempering process is performed, a screw head could be a different color; optimally, however, the resultant color would be blue.
Today, blued screws are common, but few companies still “blue” them the traditional way. (Lange, for one, still uses heat in their process). Generally, lower-end makers will use painted screws or chemically-treated screws, which, while blue, do not provide the same structural benefits mentioned earlier. As one may notice, movement decoration was in large part influenced by practicality and necessity. Particularly in earlier eras, the primary considerations for movements had to do with performance rather than aesthetics. As watches have taken on sapphire exhibition case backs and greater emphasis is placed on visual perfection, marques have leaned into these traditional details while bringing finishing quality standards to new levels.
A freehand-engraved balance cock on an A. Lange & Söhne Lange 1 - IN THE SHOP
Finally, we come to engraving. While engraving on cases and dials has been employed by certain Swiss brands such as Patek Philippe, it’s Germans brands such as Lange and Moritz Grossmann in particular that have a tradition of engraving movement componentry. In Lange’s case, every balance cock is engraved freehand. (The brand has also made a number of watches with engraved bridges as special editions.) Engraving really plays only an aesthetic role, but it’s a hallmark of boutique watchmaking and helps to infuse a human quality to certain movements that mass-produced calibers lack.
Movement Layout as an Art Form
Rexhep Rexhepi Tourbillon Chronographe Monopoussoir movement - (Image by Akrivia)
Up until now, we’ve covered the ways brands elevate the aesthetics of their movements, taking components and finishing them to perfection. One brand, however, stands out as making movement appearance a consideration in the design stage.
Independent maker Rexhep Rexhepi is one of the brilliant watchmakers of today. His movements are a work of art, with exceptional black polish, substantial mirror anglage, perlage and more, all finished by hand to the most incredible extreme. Perhaps more impressive, however, is how Rexhepi has preserved symmetry in his movement construction. He has entirely reworked the layout and organization of movements to maintain balance on both sides. This symmetry helps make Rexhep Rexhepi a step above the rest in the movement finish department.
Of course, this is merely a rudimentary overview of the basic considerations made by movement finishers and watchmakers; hopefully, it offers a greater sense of what goes into finishing a high-end watch. This becomes the largest point of separation in price between less expensive and more expensive watches. Choosing which finishes to apply and taking the time to apply them is what watchmaking as an art form is all about.