Spotlight on traditional dials
Not all watch enthusiasts know this, but dials are among the watch components that require the most manual operations before their assembly. Here is a summary of what you need to know about them, in order to better understand their importance and to avoid using the wrong terms when describing them.
The dial is the face of a timepiece and reflects its owner’s values. Being so, it requires great care during its development. As its aesthetic balance determines how much appreciation the piece will receive. Over the years, the artists who work with watchmakers have developed many techniques to increase their perceived value. Depending on the period and fashion, they adapt the techniques they use. Nowadays, many new brands have emerged, and so did the need to distinguish themselves. Dials are now at the heart of the designing of all new watch products.
Details about the enamel
Brands that are more interested in preserving the Métiers d’Arts, produce enamel dials just like they did in the past (after the 16th century). Indeed, they use a simple metal disk for these dials, usually brass or copper and occasionally gold. On those disks, the craftsmen put several layers of a high-temperature soft glass and then fire them at a temperature from 500° to 800° Celsius. After that, they affix numbers on that base plate. Which is usually white and opaque but can also vary from red to black. The artists paint them with various patterns. And then, in order to stabilise the colours, they fire these plates at each operation. Finally, to give a brilliant finish and to guarantee the material will retain its shine and colours, many factors cover these precious disks in Grand Feu enamel, of a transparent material called a couverture.
But many other types of dials use the enamel. First, there are those called flinqués. They have a surface that has been machine-engraved, hand-engraved or even stamped, covered with a transparent or translucent enamel.
Professionals often mix up enamels called champlevés and those called cloisonnés. For the champlevés dials, artists cut the base plate according to a determined pattern. Then, they fill it with vitreous enamel.
For the cloisonnés dials, enamelers create metal compartments on the plate to separate the spaces. So as to put crystals of hot vitrifying minerals in those spaces. After that, they fire it several times. Which is followed by a delicate lapping in order to get a completely flat and polished surface. Some Maisons even install a couverture on the dials as to increase their brightness.
Also, to obtain the very rare and fragile plique-à-jour enamel dial, they have to dissolve the backing of a cloisonné enamel.
For some years now, you must be careful with the terms that some Maisons use. Indeed, some of them try to take advantage and offer “cheap” dials made with cold enamel. In other words, dials easily made in large quantities from synthetic lacquers that polymerise in the air.
Classical decorations
Some dials display a surface covered with repetitive geometric patterns. In some rare cases, the craftsmen make these decorations by hand and with a chisel. During the 18th century, and even more at the beginning of the 19th century, the guillochage became common for both dials and cases. Indeed, after the development of a machine that made it possible to cut the patterns in a semi-automated way. Only a few brands still perform these surface treatments with machines. And they can now obtain it in a quicker way and at a lower cost. Either by stamping, using numerically controlled milling machines or even specialised lasers.
Sometimes hot enamel cover the decorations, or the flinquage. We call azurage the very thin engravings painted or lacquered after a circular surface treatment.
As for the soleillage, it is obtained by a surface treatment formed by lines that start from the center of the dial. Either by directly crafting the metal, or by a delicate coating of the varnish to protect the painting or the silvering of the dial.
Dial makers use the term ramolayé when referring to manual or mechanical engraving. Which they do in ronde-bosse, usually with natural material such as bone, ivory or mother-of-pearl.
Nowadays, many dials are painted or lacquered. The craftsmen make them by spraying paint with a high pigment volume concentration or by using new generation printers. Then, they place various decorative elements on these plates. Generally, they put them in ovens to stabilise the layers of paint.
But other dials have silver, gold, copper or rhodium surfaces. Brands mostly make them by electroplating, which consists in covering a base plate with a layer of metal. Frequently, they use the PVD technique. In other words, a physical deposit of material in vapour phase. You should note that they directly produce some dials from 18-carat gold or rhodium-plated silver 950 by electroplating. It stabilises the metal oxidising in the air.
In order to apply logos, brand names, railway timer, sometimes Arabic or Roman numerals and special marks, they often use pad printing with a gelatine cone. After that, many dials get a protective varnish, either cellulosic or epoxy, which the watchmaking jargon refers to as “Zapon”.
While making the dials, the craftsmen pierce their surface with small holes. On which, they place the base of the metal markers. And they may or may not set or fill them with luminous material. Then an expert secure the small pieces, placed one by one by hand, with a tool on the back of the plate. That is a dial with applied markers.
Sometimes, these markers are not riveted. Instead, machines glue them in a single operation. This treatment, the décalque en relief, is often used on mid-range watches. But sometimes, the best models of fine watchmaking are also equipped with this kind of dials.