Watchmaking finishes Our dossier on the finishes used on mechanical watch movements looks at the different techniques used and explains the often practical origins of what at first sight appears to be a purely aesthetic side to a watch movement.
Finishes Engraving: pinpoint precision ‘surgery’
No other finish mistreats the smooth surface of the metal so intensely and deeply as engraving. Portrait of an artistic cut showcasing a variety of techniques.
All means of decorating watch components ‘attack’ them in some way. Generally involving methodical scratches, they leave traces in the very matter from which the movements are made. Yet engraving is far more than a scratch; it does not merely caress the surface to trace a motif. Instead, it literally tears into the metal, incising, cutting and ‘wounding’ it. And as always, the raw strength mastered by the human hand is capable of making beauty spring from a ‘surgical’ operation.
The engraving surgeon’s first tool is the ‘scalpel’, known as a burin or engraver. This long, pointed-tipped, regularly sharpened hard steel tool pierces the ‘skin’ or the brass, maillechort or steel from which the mechanical components are made. The hand then presses even harder to trace a groove in a given shape that is the object of this ill-treatment. The metal shaving lengthens as the motif gradually appears, generally an acanthus leaf-type or abstract pattern. Saxon watchmakers tend to use in a specific area, such as on the balance-wheel bridge known as the balance-cock. An engraved balance-cock is indeed a signature feature of watches by Glasshütte Original or A. Lange & Söhne. In 2015, Vacheron Constantin has made it the very principle of its Métiers d’Art Mécaniques Gravées series, on which the two sides of the movement – the dial and bridge faces – are entirely hand-decorated and selectively blackened to highlight the motif. All of which takes a full month’s work that is more physically demanding than any other in the watch industry.
Nonetheless, the strength required for engraving is not brute force, and there is indeed one particularly specialised field in which control is everything. Historically, skeleton-worked movements are also engraved on their few remaining solid surfaces. These zones are by definition narrow and vulnerable, yet all the more important in that they are the last ramparts protecting the rigidity that is indispensable to movement operation. Distorting it by pressing too hard, or damaging it by cutting too deep, would jeopardise the longevity of the movement itself.
Occasionally, a decoration method usually reserved for dials may also be applied to movements. After all, both are made from the same materials and share a number of common denominators. Guillochage (also known as engine-turning) is indeed a type of engraving, except that the motif is programmed on a machine. The speed at which the latter moves forward and the subtle changes of motif creating geometrical effects are hand-guided in the best-case scenario, although often automated. When applied to movements, guilloché is most frequently used on oscillating weights.
The latest tool used by the engraving surgeons is more modern, more intense and more automated. Laser engraving is by far the most widespread of all techniques, and for good reason, since it serves to create the numerous inscriptions appearing on movements. Serial numbers, brand names or model names, the number of jewels, details regarding rating positions: all of these inscriptions, some of them mandatory and serving an essentially decorative purpose alongside their informative role, are made at the end of the production chain by specialised machines. This does not prevent the latter from occasionally performing longer, smaller operations that sometimes represent true feats in themselves. Greubel Forsey has for example been known to write hundreds of letters on the baseplates of certain superlative models. The human hand cannot hope to achieve such an extreme degree of finesse, regularity and precision. This is a fine example of the noble nature of machinery, even when of the electronic variety.
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