In the Details: Guilloché Techniques

Guilloché is perhaps the most immediately visible of the many decorative watchmaking arts, and while there’s been considerable progress in micro-techniques, the craft itself has actually changed very little. Enter the secret world of guilloché engraving.

What’s the difference between the original guilloché engraving of the sixteenth century and that of today? The answer is almost none, at least as far as the fundamental principles are concerned. Guilloché was and is a process of decorating a metallic surface with geometric patterns.

Some say it was a French engineer named Guillot who first developed a lathe for engraving patterns on metal. Other sources assert that guilloché was invented by Hans Schwanhardt, a German. Opinions may differ on that point, but all agree that the watchmaker Breguet went on to make the art an essential component of his creations, and thus of watchmaking in general. To this day, the Breguet manufacture is one of the masters of the craft.

Just a visual art?

Some commentators see guilloché only in terms of aesthetics, but that view is very much open to dispute. For one thing, by definition an engraved surface is no longer smooth. Guilloché engraving prevents flat or polished surfaces from becoming prematurely tarnished and mitigates their otherwise fragile nature – prone to scratches, blemishes, and all kinds of harm. There’s nothing more difficult than preserving the sheen on a large mirror-polished metallic surface. In addition to offering an aesthetic bonus, guilloché engraving provides protection against tarnishing.

In similar fashion to movement finishings, guilloché is also a way of improving light diffusion across the surface in question. On a dial, this is essential: it makes it easier to read the time.

A final consideration is that guilloché is a way of trapping any dust or impurities. This was absolutely vital a couple of centuries ago, at a time when watertightness and indeed airtightness were beyond the realm of imagination; nowadays, this aspect is less of an issue thanks to the advent of sealed cases.

Breguet’s historic mission

While guilloché offers these three attributes of cleanness, readability, and dust protection, modern work can thus focus solely on readability, allowing the development of much finer, elaborate, and even hollowed-out hands. Brands can use it in one of two ways: to divide the parts of a dial into separate sectors (making it easier to read), or to provide timepieces with a decorative feature.

Breguet reigns supreme in both of these applications. Having produced the oldest-known guilloché watch in 1786, Abraham-Louis Breguet went on to elevate guilloché to the rank of watchmaking art – and when the Hayek family took over the Breguet manufacture in 1999, this know-how was preserved. Today, Breguet has an entire department devoted to guilloché engraving, complete with 25 lathes and 20 guilloché engravers.

A dearth of machines and training

Most of the machines in question are over one hundred years old, and constant care is required to maintain them in good working order. Acquiring any others (any of which will be just as old) is a treasure hunt, with all the leading brands joining in, scouring yard sales and auction rooms across Watch Valley in the hope of laying their hands on one of these beasts – weighing in at several hundredweight – over which time seems to have no hold.

Similar challenges apply when it comes to the artisans in question. In spite of the interest of collectors (and thus of brands) for the craft, formal training for guilloché engravers has died out since the final efforts of the late Pierre Rosenberg to pass on his knowledge. As the Fondation de la Haute Horlogerie euphemistically puts it, training is now “in-house”. What this really means is that there are no longer any schools teaching the art.

Man or machine?

There may no longer be any formal training for humans, but the machines are still capable of applying the patterns programmed into them, as a result of which machine guilloché has taken over from hand guilloche, so much so that it’s become very difficult to tell them apart.

Nevertheless, Breguet is still very committed to hand guilloché engraving. There’s a corpus of a dozen or so enduring, iconic patterns, instantly recognisable to the experienced eye even if their names – Clou de Paris, barleycorn, edging, filet, and so on – aren’t always familiar; real connoisseurs will be able to pick out ‘circular cross weave’, ‘art deco cube’, and ‘checkerboard’ patterns, too. At the same time, new creations are regularly accompanied by more modern patterns created by Breguet. For example, the manufacture has developed a wave motif for its Hora Mundi, also to be found on the convex dial of its new Marine collection, as well as a diamond guilloché on the movement bridges of certain titanium timepieces.

New wave

Today, most brands offering a traditional collection are pretty much obliged to offer a guilloché dial to match. And not just a dial: amid the rise and rise of sapphire casebacks, guilloché has become just as inescapable on certain visible parts of the movement. The sunburst guilloché is the most frequent: used on a dial, the pattern generally radiates out from the center – although Piaget has an interesting off-center variant, as do certain Chopard models.

Today, in addition to Breguet, Kari Voutilainen has become a past master in the art. Chronoswiss makes extensive use of it too, carrying out its own guilloché engraving in-house and producing a maximum of one or two timepieces a day, combined with bright colors that have added a fresh spark to the genre. Japanese firm Seiko has also used the art on its timepieces, and Montblanc has made it a hallmark of its Rieussec chronograph. With so many examples abounding, guilloché is clearly immortal.