CIRCULAR GRAINING (CERCLAGE)
Circular graining, or cerclage, is a finishing technique often employed for surface treatment of circular components. It can be applied to parts of various sizes, including those belonging to the case, dial, or movement of a watch.
Definition
Circular graining is achieved by abrasively treating a surface in a circular motion. The satin-matte effect it produces is similar to satin finishing, but while satin finishing consists of parallel lines, circular graining features concentric circles. This technique is traditionally applied to circular components such as discs or rings, with surfaces that may be flat, convex, or concave.
Components Suitable for Circular Graining
Circular graining can be applied to most circular components, whether from the watch’s exterior or movement.
- Case: Circular graining is often applied to the top of the case middle, the interior or exterior of the case back, the bezel, or even the crown and pusher heads.
- Dial: It may be used to texture a dial’s surface or, more commonly, to decorate subdials.
- Movement: Circular graining is frequently applied to various movement components, such as train wheels or hour wheels, and is a traditional decorative finish for these parts.
Techniques
A variety of machines and tools can be employed to perform circular graining, whether for a single piece or industrial production. In some cases, the component remains stationary while the abrasive rotates; in others, the reverse is true. In every instance, the process begins with the precise alignment of the abrasive and the origin point of the decoration on the component (typically its axis of rotation).
Handcrafted Circular Graining
There are many methods available to artisans, with no significant distinction in quality. The artisan selects the method based on the tools at their disposal. A lathe offers excellent support (of any type). For example, on a bench lathe (such as a Schaüblin 70 or 102), the abrasive can rotate in the spindle or remain fixed in the tailstock. Circular graining on a lathe can sometimes save time, as the decoration of a surface can follow directly after machining. The most common artisanal method involves using a sensitive drill. With this option, the abrasive is typically placed in rotation within the drill spindle.
Semi-Industrial and Industrial Circular Graining
Similarly, the industry has access to numerous tools and machines for circular graining. There are many types of machines dedicated to decorative operations. These machines vary in versatility and automation levels, and the choice depends on the desired quality and production volumes.
At the industrial level, a distinction can be made between decorative circular graining applied post-machining and circular graining resulting from fine machining, such as what can be achieved using a CNC machine or an automatic lathe.
By combining artisanal and industrial techniques, circular graining can be applied to a wide variety of components, from the case to the movement and dial, offering refined and consistent finishes that enhance the overall aesthetic of a watch.