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GUILLOCHÉ (ENGINE-TURNING)

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1. Introduction

Guilloché (engine-turning) is an Engraving involving the engraving of very fine grooves using a machine that allows for precise and regular machining.

The most artisanal technique requires a traditional guilloché machine, which allows material to be removed using a Graver. All precious metals can be guilloché, from different types of Gold to Main plate, as well as more surprising materials, such as Mother of pearl. Once the choice has been made between the straight line technique, the Rose engine (guilloché lathe), or the tapestry lathe, the settings and any potential Die are then made according to the pattern and the Material to be worked.

There are three categories of guilloché machines depending on the type of work to be carried out: the Rose engine (guilloché lathe), which allows for the creation of circular decorations where the grooves intersect and intertwine, the straight line, which allows for a linear decoration, and the tapestry lathe which allows for the reproduction of a geometric or figurative pattern from a Die.

The quality of the Guilloché (engine-turning) depends on meeting certain conditions: the Graver must be adjusted according to the material used and the desired depth. A correct Graver height is also essential to ensure the regularity of the pattern. The piece must be laid flat to allow the guide to be in uniform contact with the surface all around its circumference.

A traditional craft, Guilloché (engine-turning) often revives old and classic patterns. But the Guilloché engraver may be called upon to renew the genre, particularly to reinforce brand identity. Their talent requires a good knowledge of the mechanics and machines that they must restore and maintain.

2. Guilloché (engine-turning) (video)

3. The Rose engine (guilloché lathe)

This is a manually operated machine designed to engrave concentric geometric patterns. The component to be engraved is placed on a movable Arbor guided by a Cam (sometimes called a rosette). The Graver is held under pressure against the piece being guilloché, which rotates following the profile of the rosette. Historically, Guilloché (engine-turning) is a decoration applied mainly to backs of Cases as well as dials.

(see the Rose engine (guilloché lathe))

4. The straight line

The straight line is a traditional mechanical instrument used in Guilloché (engine-turning) for engraving linear and repetitive geometric patterns on surfaces metallic, notably dials and Cases of watches. Emerging during the 18th century, this machine relies on a system of Cams, levers and carriages allowing the controlled movement of a Graver along a rectilinear plane, while the piece being guilloché-worked oscillates following the profile of the cam.

(see the straight line)

5. Guilloché (engine-turning) patterns

The illustrated patterns bear very different names depending on their size and shapes:

• barleycorn
• rice grains
• Paris nails
• rack pattern
• “Flinqué” (engine-turned engraving)
• alternating “Flinqué” (engine-turned engraving)
• old basket pattern
• alternating basket pattern
• basket pattern
• circular basket pattern
• radiant sunburst
• border line
• Thread
• waves
• moiré drape
• fabric
• radiance
• rosette

6. The Rose engine (guilloché lathe)

The Rose engine (guilloché lathe) is a machine for Guilloché (engine-turning) mechanical, used to reproduce complex decorative patterns on the dials or case backs. This tool stands out for its unique ability to faithfully reproduce figurative patterns engraved on a Die, known as tapestry patterns, which give it its name.

(see the tapestry lathe)

7. History and etymology

Guilloché (engine-turning) is a very ancient engraving technique that involves removing material and carving regular, repetitive grooves into a metal surface. The goal is to achieve grooves that are very close together or interwoven, creating a harmonious play of Light.

Unlike hand engraving, which allows the creation of shapes such as landscapes or animals, Guilloché (engine-turning) allows precise patterns to be engraved, repeated identically. Guilloché (engine-turning) is purely decorative; its only function is to move and to give pleasure.

Guilloché (engine-turning) does not originate from horology; it existed long before and was used on materials such as Mother of pearl, Wood or even porcelain. Horology adopted this technique as early as the 18th century to make it an element of regular and refined decoration, reserved for the most prestigious timepieces.

Sources differ as to the origin of the word. The technique of Guilloché (engine-turning) is said to owe its name to a worker, Guillot, who supposedly “invented” it. This claim is repeated in the Dictionnaire de la langue française written by Émile Littré (1801-1881) in the 19th century, who himself took it from the 1750 edition of the Dictionnaire étymologique de la langue Françoise by Gilles Ménage (1613-1692), great grammarian and historian of the French language.

This version is still disputed in the 19th century. The Etymological Dictionary of the French Language (8th edition), by Auguste Brachet (1845-1898), tells us that “to guilloché derives from Guilloche, the name of the inventor of the ornaments called guillochis”.

Eugène Jaquet (1884-1951), historian of Swiss horology, writes that it was a man named François Guérint, from Geneva, who was its inventor, without however specifying his sources. Guilloché was practiced in Geneva around 1670, that is, more than a century before his birth, he states, which seems unlikely.

Etymologically, “to guilloché” is a word from the 16th century that would come from the Italian ghiocciare (“to drip”, “to trickle”), itself a blend of goccia (“Drop”) and ghiotto (“glutton”); it is assumed that ghiocciare has the meaning of “to decorate with interlaced lines” due to the architectural meaning held by the Latin gutta, the Italian goccia, and the French Drop.

Another origin has also been put forward: the word may derive from guille (“stick”), a variant of quille due to the shape of the ornaments (Alain Rey, Dictionnaire historique de la langue française, Dictionnaires Le Robert, Paris, 1992, 6th edition, 2022).

First applied to jewelry, mainly to objects and feminine accessories such as powder compacts, mirror backs, etc., Guilloché (engine-turning) was used as early as 1786 by Abraham-Louis Breguet (1747-1823), who was almost certainly the first to use it for metal dials. This form of Decoration was favored by the master Horologist (watchmaker), who used it extensively.Its patterns, universally recognizable, are named, among others, “clou de Paris,” “crémaillère,” “flinqué,” “grain d’orge,” “grain de riz,” or even “vieux panier.”He would be followed by many other Horologists (watchmakers).

The Guilloché (engine-turning) technique does not appear as freehand Engraving on watch Cases before 1770 and remains very rare before 1790.

Over the centuries, guilloché machines were perfected, notably in the 18th century, to work precious Metals. This technique would experience extraordinary growth throughout the 19th century.

Then “Guilloché (engine-turning)” was to go through a long desert crossing. Training in “Guilloché (engine-turning)” would gradually disappear in favour of “Engraving”. For decades, the low interest in this art craft led to a marked decline in the activity.

Against all odds, the 1980s were marked by a timid revival of interest in this age-old technique, which went hand in hand with the renaissance of mechanical horology.

Since the 2000s, major brands have brought it back to life within their manufactures, and independent “Horologist (watchmaker)s” have taken an interest in passing on this know-how. Despite digitalisation, “Guilloché (engine-turning)” remains an ancestral technique that allows for the creation of unique pieces. The machine is then an extension of the “Guilloché engraver”‘s hand, since it is he who, based on his sensitivity and experience, applies the pressure needed for the “Engraving” in order to avoid the slightest irregularity.

8. Artisanal method

For manual “Guilloché (engine-turning)”, it is the piece that moves in front of the “Graver”, which itself is fixed, unlike “Milling”, where a rotating tool moves along a piece.

Each hand-guilloché piece will have the particularity of revealing luminosity and creating an impression of relief, thus giving an effect of volume.

Specialized companies and Guilloché engraver craftsmen are very few in number today. Guilloché (engine-turning) is pure craftsmanship. There is no training school and the necessary machines are no longer manufactured.

Prestige brands use old and very rare machines that they restore. The pieces to be guilloché are particularly carefully finished in terms of flatness in order to avoid any distortion of the patterns. They are also smoothed and matte-finished using a finishing paste, in order to bring out the guide mark during the actual craft guilloché process.

Guilloché (engine-turning) calls upon qualities that are both artistic and technical, particularly mechanical. The complexity of this work and the skills required limit this type of Decoration to top-of-the-range watches.

Rose engines (guilloché lathes) have not been manufactured since the 1960s. As a result, these machines are also true collector’s items. The oldest machine still in working order dates back to 1770. It belongs to an independent Guilloché engraver who handles it with great care.

It is often the craftsmen themselves who repair their machines when they break down. The Guilloché engraver maintains a close relationship with his machine.

9. Industrial method

There are two industrial methods capable of imitating the patterns of traditional Guilloché (engine-turning). The first is possible through machining using a computer numerical control (CNC) center. The pattern will then be milled and, in the best case, diamond-cut. Machining marks will sometimes be visible, and the shine obtained by cutting with the Graver is impossible to faithfully reproduce. The other method consists of stamping the material with a die machined or hand-engraved. Here again, the brilliance of the reflections from a hand-guilloché finish is impossible to reproduce.

These two methods make it possible to produce large series at a lower cost. However, they remain incomparable to hand guilloché in terms of precision and contrasts. The use of the term “guilloché” is rightly very controversial, even totally incorrect, whenever the result is obtained by one of the two methods described above.