The dial of a watch is rightly called its face. Visually, it is the most important component of the timepiece, but it is often neglected with frequently more attention being paid to the movement.
Dials, like movements, are distinguished by how they are finished. Most commonly they are plated brass. The dial itself can be finished in several ways prior to plating, with one of the most common being brushed or matte finish of the metal, which is then coated with a clear lacquer for protection. Synthetic lacquer can also be coloured and opaque and that is akin to painting the dial.
But lacquer can also be natural, as Chopard and Vacheron Constantin have done with their maki-e watches. These feature dials decorated with Japanese lacquer, also known as maki-e (‘sprinkled picture’). Natural lacquer is obtained from sap of the aptly named lacquer tree, which also provides the lacquer used by other East Asian cultures. Maki-e takes lacquering a step further for it includes decorative motifs in the lacquer created by sprinkling gold dust, crushed eggshell and other materials.
Lacquer is however fairly unusual at the high-end of watchmaking. More common are dials made of precious metal, often gold or silver, which are then engraved with a repeated decorative pattern known as guilloché. The most expensive guilloche dials are hand-decorated. The means the dials are made on a hand-operated rose engine which engraves a repetitive pattern on the dial.
Guilloché can also be done by a CNC machine that engraves pre-programmed patterns onto the dial blank, but the sharp eyed can spot the difference between hand-engraved and CNC machine-engraved, primarily in the variation in the end of the stroke in an engraved line. Guilloché can also be made via stamping – this is the cheapest and least attractive method of guilloche as the result lacks the careful and delicate lines of engraved guilloche.
But precious metal dials can also be finished plainly, like A. Lange & Söhne does with its solid silver dials. They are either lacquered or plated to prevent oxidation, and finished with a simple finely grained pattern.
However, precious metal dials can also serve as a base for enamel. Enamel is deceptively simple looking but devilishly difficult to manufacture. Enamel dials are made by melting glass powder onto the metal dial blank by fire it in an oven.
Such dials are expensive because of the effort needed to paint and fire the enamel. One needs knowledge of how the enamel powders mix and what they look like after firing to obtain the right colour. And the dial has to be heated just right so that the right colour and finish is achieved. Multiple firings are needed for dials with varied colours and tones.
Enamel dials also result in high rejection rates due to the unpredictability of the result after firing. Dials often emerge from the oven in the wrong colour, or having warped due to the shrinkage of the enamel over the base.
The most common type of enamel dial is the semi-glossy, grand feu enamel dial. At the lower-end such dials mostly have numerals and lettering that are printed after the dial is fired, but the most expensive dials usually have markings that are painted enamel. Such dials can also be additionally decorated with hand-painted motifs, a technique known as miniature painting.
Grand feu enamel dials are typically white. Black is rare for achieving a consistent black shade across multiple samples is so difficult as to be uneconomical. Independent watchmaker Laurent Ferrier offers the choice of white enamel or black onyx for the dial of its Galet Tourbillon for that very reason.
Beyond simple enamel dials of a single colour, various enamel techniques can be employed to create a vibrant motif. Several techniques are employed on watch dials, with one of the best known being cloisonné, where the motif is formed by tiny gold wires.
Faux enamel, which is essentially epoxy paint, can mimic fired enamel quite well but is not the same. Notably Philippe Dufour chose to use a faux white enamel dial for his Simplicity watch, because a real enamel dial would have required a thicker case as an enamel dial is thicker than a similar-looking lacquered brass dial.
Another pricey dial material is semi-precious stone, like onyx or lapis lazuli. While not extremely expensive in themselves, these materials are difficult to work with. They have to be sliced very thinly in order to create a watch dial, and in the process they often crack. Additionally, stone dials are brittle and tend to crack easily when holes are drilled or cut for apertures or for the hands. As a result, sometimes they backed with brass for stability.