Cooking glass

Enamelling is one of the more common metiers within watchmaking, and is almost always used to produce watch dials that aren’t just visually attractive, but also immutable. Don’t let this craft fool you though – although enamel dials are someone more accessible relative to other metiers discussed here, the process to creating each one is a treacherous journey that demands strict quality control and much finesse.

Enamel is essentially vitrified glass – coloured glass powder is baked under high temperatures to melt it, before being allowed to cool into a single solid mass. The intricacies of this metier lie in the variations that exist in every step of the process. For a start, not all glass powders are equally manageable. Black enamel, for example, is notoriously difficult to produce as the powder must be absolutely free of impurities, since even a single speck of dust will be extremely obvious on a smooth black surface. This is the reason why many brands offer white enamel dials in their watches, but either black lacquer or onyx dials in lieu of an equivalent one in enamel.

Enamels are also differentiated by how they are fired (i.e. baked in a kiln). Grand feu (lit. great fire) enamel lies at the upper limit, with firing temperatures exceeding 820 degrees Celsius. This limits the range of colours that can be produced, but also tends to create greater depth in the surface of the finished product. Enamel can be fired at various other (lower) temperatures, depending on desired final product.

Temperature aside, how enamel is applied matters too. The glass powder is typically mixed with a solvent such as water or oil to create a “paint” that can be applied with a brush, with the solvent evaporating during the firing process. To prevent the “paints” of various colours from mixing, there are two common techniques: cloisonné enamelling uses thin wires to form raised cells which are then filled in with enamel, while champlevé enamelling involves excavating the dial base to create hollows instead. More exotic variants include plique-à-jour enamelling, which creates translucent cells a la stained glass windows, and grisaille enamel, an extremely demanding technique of painting a motif in white onto a black enamel surface.

Jigsaw art

Marquetry is a fairly specialised and uncommon craft within watchmaking, and involves cutting and fitting different materials onto a dial base to create a motif or pattern – forming a jigsaw puzzle with the selected material(s), if you will.

Technically, any conceivable material can be used; the only limits here are the skill and imagination of the craftsman. On a practical level, however, marquetry poses many unique challenges. To ensure that the dial doesn’t become overly thick and fall outside the tolerances set during the watch’s design, the material being applied to the dial blank must fall within permitted limits, which translates into a thinner – and structurally weaker – material.

The materials themselves also pose different problems. Wood, for example, reacts differently when being cut against and along its grain. It can also warp or chip while being cut. Stones like marble, on the other hand, are extremely hard and difficult to shape. Naturally varied materials like feathers or petals, meanwhile, are difficult to match by colour and texture to form a coherent product.

Colour mutation

Patination isn’t a formally defined craft, but various processes and techniques are used to produce patinas on watch dials, whether just for visual oomph or to “paint” a specific motif. The underlying principle is generally the same: a metallic dial surface is treated chemically, with the reaction producing a decorative patina that contrasts with the untreated surface.

One material that has been recently introduced to watchmaking (by Blancpain) is shakudō, a traditional Japanese alloy of copper and gold that, when untreated, looks like a cross between copper and bronze. Historically used in smaller items such as sword guards, or as accents for larger objects, shakudō does not spontaneously react with air to develop a patina. Instead, it must be treated with rokushō, a solution of copper acetate and a few other chemicals, to induce patination. Depending on the exact formulation of the rokushō used, as well as the length and number of times it is applied, shakudō can acquire a patina that ranges from blue to a rich violet to black.

Cartier’s proprietary flamed gold, on the other hand, uses heat to oxidise a special 18K gold alloy with an unusually high iron content (Cartier developed this alloy jointly with its external supplier). Depending on the temperature that this gold alloy is heated to, it acquires a patina that ranges from beige to brown to blue – not unlike how steel is blued by applying heat. Creating a flamed gold dial is akin to painting with fire. The dial is first heated to the highest temperature with a torch to create an even blue surface, before the unwanted portions are scratched off with a ceramic tool. The dial is then heated to the next highest temperature toproduce the next shade, and unwanted sections are scratched off again. By working down the range of temperatures, the craftsman slowly “paints” the dial with various colours of the oxidised gold alloy.

Micro excavation

Engraving entails the removal of material with tools to create patterns and images. Its beauty lies in its versatility; nearly every part of a watch is fair game, from the dial to the case, to even movement components. Engravers typically work free hand using steel-tipped tools called burins that are customised for each individual, and often do so through microscopes due to the small size of the components being engraved, and the level of detail that must be achieved.

For an engraver, the challenge is manifold. As mentioned above, the small size of watch components is definitely a concern, since it demands a high level of finesse and attention to detail. Thickness – or the lack of it – is a related issue. Since components such as bridges and dials must be kept as thin as possible to limit a watch’s height, an engraver must, by extension, keep his work to a certain depth, or create depth perception using other visual tricks.

Materials have their individual limitations too. A steel case will be harder to engrave compared to a gold dial, since it is harder and thus requires specialised tools and a stronger touch. The same gold dial may, however, be unable to “hold” micro-details or sharp angles due to its softness. For the engraver, the challenge is to present the best possible result by working within the limits of the component being engraved.

Line work

Guillochage, also known as engine turning, involves cutting intersecting lines into a dial’s surface to create regular, recurring patterns. Given its decorative nature, the dials being worked on are typically precious materials of silver or gold. The finished product is sometimes finished with a layer of translucent enamel, with the final product called flinque enamel.

Producing guilloche is largely a manual process, although it does utilise two machines: the straight-line engine that cuts straight lines, and the rose engine that cuts curved ones. These machines are an improvement over fully manual labour as they help to cut the lines more accurately and evenly, but it is still the guillocheur (i.e. the craftsman) who rotates the dials being worked on and advances the cutting tool of the machine. The common thread running through several metiers d’art, guilloche included, is finesse: it is the guillocheur’s hands that control how evenly and closely the lines are cut, as well as how the lines themselves play across the dial.

Guilloche is prized for the time and work required to produce it, as well as its visual appeal – the finished dial is textured in such a way as to play with light at different angles from afar, while offering up intricate details for examination when viewed up close. Cheaper alternatives to guilloche now exist, from CNC machines that can mill out patterns, to dials that are stamped to create guilloche patterns. Ironically, the economical mass production options are given away by their perfection; it is the little imperfections that reveal a hand-turned guilloche dial as the real McCoy.

Crystal method

Within the watchmaking industry, the craft of crystal-making is probably the exclusive domain of Hermès, thanks to its full ownership of French crystal maker Cristalleries de Saint-Louis, which has been in existence since 1767. Hermès was inspired by Saint-Louis’s crystal paperweights, and first adapted them for its watches in 2014 with the Arceau Millefiori series of watches, which sport crystal dials with the eponymous millefiori pattern.

Millefiori literally translates into “a thousand flowers”, and refers to the pattern formed by coloured crystal, which resembles a bed of flowers. To create such dials, crystal of various colours are first fashioned into thin canes, which are then cut into short sections each measuring around 10 millimetres long. These canes are then arranged within a cast-iron bowl to form the desired pattern, before a blob of molten, transparent crystal is applied to “seal” the entire arrangement. The transparent crystal is allowed to cool and solidify, and the finished product is then cut into thin slices. Voila, a watch dial!

In 2018, Hermès revisited the millefiori technique, but opted to create a more primal and animalistic motif instead. The Arceau Pocket Millefiori released this year has a dial created with black and white canes instead. These canes are also four-sided instead of round, and arranged to form a pattern reminiscent of an alligator’s scales, in a clear demonstration of the technique’s versatility.

Bead it

Granulation is yet another relatively uncommon technique in watchmaking. The traditional form of this craft involves setting beads of a metal (usually precious) onto an object to create a textured surface. Depending on the size of the beads used, as well as how they are arranged, different patterns and even motifs can be created. The devil’s in the details here – good granulation work isn’t just detailed but also seamless, with no hint of how the beads are attached, whether via soldering or direct bonding.

Cartier has developed a derivative technique to granulation using enamel called, quite simply, enamel granulation. In lieu of metals, the beads are enamel produced in a tedious, multi-step process. Thin rods of enamel are first created in different colours and diameters. Cutting a section of such a rod off and melting it with a blowtorch causes it to coalesce into a molten bead of enamel, which is then allowed to cool and solidify again. Depending on how much “material” was used, beads of different sizes can be made.

With a supply of such beads (sorted by size and colour) at his disposal, the craftsman can begin the process of enamel granulation. In Cartier’s only work with this technique so far, the beads are set to form a panther motif, with the animal’s outline created by wires a la cloisonné enamelling. The enamel beads are applied colour by colour to the dial, with intermediate firings between colours to set them. The final product? A textured, colourful dial that combines the best of both granulation and enamelling.

Stone age

Gem-setting is extremely common within watchmaking, and discussing it here almost seems unnecessary. This ubiquitous technique is still worth a closer look though, given its intricacies and recent developments.

Perhaps the most interesting thing about gem-setting is how almost any design can be brought to life simply by varying the type and cut of the gem(s) and the setting technique. To completely cover a surface with baguette-cut diamonds using invisible setting, for example, will produce a very different look from snow-setting brilliant cut diamonds. Sorting and matching gemstones by their various properties is also an art (and science) unto itself.

Recent advancements in gem-setting have resulted in new products that were previously impossible to produce. For a start, tighter production tolerances have now allowed workarounds that enable gemstones to be set into non-metallic materials including ceramic, carbon, and rubber. In lieu of traditionally used gold or platinum, these materials have entirely different colours and textures, and convey a technical vibe that’s unconventional, to say the least.

A minor revolution also took place at Cartier in 2015, when the maison unveiled a new technique: vibration setting. This is a modern take on an older technique called trembling setting, with the diamonds set with an as-yet-unrevealed mechanical structure such that they wobble ever so slightly when disturbed, as if mounted on a spring. The diamonds’ vibrations causes light to refract and reflect off them randomly, for a dynamism that’s starkly different from the typically static stones.

Letting light through

Filigree, lacework, and papercutting are all variations on a theme, each developed to create an openworked piece of art. In the context of watches, the techniques are showcased in the form of light and delicate dials that lend a sense of airiness to the watch, much like a skeletonised movement.

Filigree is a goldsmithing technique where extremely thin gold threads are twisted and curled into their desired shapes, before these individual elements are soldered together to “assemble” them into a complete piece of work. The craft is difficult not just because a watch’s size necessitates working on a smaller scale, but also due to the delicate nature of the work, which requires precise control over how the gold threads are manipulated.

Lacework, on the other hand, is almost like the opposite of filigree – instead of “building up” towards the final product, lacework has the craftsman removing material from a solid gold plate. Holes are first drilled into the plate, before additional material is manually removed with saw blades. These spaces are gradually enlarged and shaped until only delicate “walls” of solid gold are left between them, so thin that they almost seem like lace.

Like lacework, papercutting is a process of reduction. The subject this time is paper, which is cut using various tools, again to create the desired motif.

Surface impact

Techniques to decorate metallic surfaces by hammering them have developed in parallel in different parts of the world, and various brands have adapted these crafts for watchmaking. Audemars Piguet is one of them, having adapted the traditional Florentine technique in collaboration with Italian jewellery design Carolina Bucci to produce its proprietary frosted gold finish. The Florentine technique sees the craftsman hammering indentations into a metallic surface for a textured finish, without removing any material from the object being worked on. In Audemars Piguet’s case, a specially developed tool with a diamond tip that vibrates at 200 hertz is used to apply these indentations and produce a finely speckled surface that shimmers and sparkles, just like a frosted finish.

Casio, meanwhile, has called on the expertise of Bihou Asano, a third-generation master of tsuiki. This traditional Japanese metalworking technique has the artisan shaping a thin sheet of metal by hammering it into a three-dimensional shape. Historically used for copperware and other metal containers, tsuiki is used in several MR-G timepieces to produce decorative indentations on the bezel and bracelet. Depending on how the technique is applied, various patterns can be created, from a series of round dimples to long, thin, and parallel grooves.