English edition

Swiss movement finishing: anglage, black polishing and Geneva stripes

A finished movement presents several kinds of light at once. A bridge carries a soft striped reflection. Its narrow bevel catches a bright line. A polished steel component can become almost black when the watch tilts. These effects come from different combinations of geometry, texture and lighting. A successful finish preserves the part’s mechanical requirements while giving each visible surface a deliberate character.

Finishing therefore begins with a surface plan. The upper face, perimeter, flank, screw recess, bearing seat and bridge support do not have interchangeable requirements. Applying a decorative texture indiscriminately can change an assembly surface or leave abrasive residue where it cannot be tolerated. Precision manufacture and decorative work need a shared drawing.

Functional surfaces and decorative surfaces

A mainplate and its bridges locate the movement’s bearings and support the gear train. Their contact faces establish the assembled relationship between components. A pivot, tooth profile or jewel seat has a different task from a broad, visible bridge surface. These distinctions determine where material may be removed and which areas must remain protected.

Deburring removes unwanted projections; smoothing, polishing and burnishing can also serve functional purposes. Decorative stripes, however, do not independently establish lower friction or a better daily rate. Those outcomes require testing of the relevant mechanism. A surface can look excellent under a loupe while its dimensions remain unsuitable for assembly.

Machining establishes the geometry

CNC machining and automatic turning establish outlines, pockets, holes and reference features. Hand finishing can follow these operations. The two approaches are compatible: the machine provides repeatable geometry, and subsequent tools refine selected surfaces and transitions. A polished appearance alone cannot reveal the complete manufacturing route.

Accessible radii and tool paths matter before polishing begins. A rotating cutter leaves a radius in a concave corner. If the intended decoration calls for a sharper intersection, the route needs a suitable secondary operation and access for its tool. The drawing should distinguish an intentional radius from a corner that must be refined. It should also identify surfaces that cannot be reworked without a dimensional check.

Anglage: controlling a narrow surface

Anglage creates and polishes the transition between a component’s top surface and its flank. Its quality depends on more than brightness. The bevel should follow its intended width and section along straight portions, curves and intersections. A sudden widening can make a delicate bridge appear heavy; uncontrolled rounding can erase the boundary with the decorated face.

The appropriate bevel is defined by the component rather than by a universal angle or width. Flat and curved interpretations require different support and contact conditions. At an inner corner, the tool must reach the intersection without damaging the adjacent flanks. At an outer corner, excess local pressure can blunt the point. These are geometric problems before they are polishing problems.

A useful inspection changes the light direction while following the edge. A continuous highlight helps reveal waviness and interruptions, but it is not a dimensional measurement. Width, remaining thickness and any specified contour still need their own checks. Sharp internal intersections can indicate demanding work; a photograph alone does not prove a wholly manual process.

Black polishing: a reflection effect

Black polishing, also called poli noir or poli bloqué, is a highly reflective finish associated with carefully flattened surfaces. The dark appearance is an optical effect. The same metal can reflect a bright source at one orientation and a dark surrounding area at another. It does not need a black pigment or black coating to produce this change.

Flatness, local texture and cleanliness contribute differently. A surface with low roughness can still be curved. A nominally flat surface can still contain scratches that scatter light. Residual polishing compound or a fingerprint can interrupt the reflection even when the underlying form is satisfactory. Increasing exposure or making a photograph darker does not demonstrate a better polish.

Production must control the support beneath the component, contact pressure and the condition of the polishing surface. A thin part that bends under load may not retain the intended form after release. Final inspection therefore examines the clean, unloaded component under a defined lighting arrangement and separately checks any required geometric tolerances.

Geneva stripes and perlage

Côtes de Genève, or Geneva stripes, give broad movement surfaces a repeated directional texture. Their visual quality depends on spacing, direction, overlap and the way each band ends at an edge or recess. Where a design expects a pattern to continue between bridges, their assembled positions become part of the decorative setup.

The stripes are a surface treatment, not deep structural ribs. Variations in tool contact, support or feed can produce inconsistent bands. The desired effect also changes with lighting, so a reference sample should be compared under repeatable conditions rather than by an isolated photograph.

Perlage uses overlapping circular marks to create a different optical rhythm. Circle size, overlap and row placement establish its appearance. It can be applied to a mainplate, pockets and other specified areas. Perlage is not the same pattern as concentric turning marks. Its presence does not establish that a movement has passed a particular certification or that it will keep better time.

Flanks, screws and recesses complete the composition

A bridge’s top decoration can be cleanly separated from a straight-grained flank by a polished bevel. This contrast makes the outline readable. Finishing a screw also requires attention to the head perimeter and slot: polishing the top while damaging the slot corners compromises the result. Recesses around screws and jewels introduce another transition whose geometry must remain controlled.

The finish plan should show where each treatment stops. A decorative operation that crosses into a support face or bore can alter the part’s fit. Protecting these boundaries is more useful than treating the whole component as one uniformly glossy object. Hidden areas also need appropriate deburring and cleanliness, even when their decorative treatment differs from visible areas.

Materials, coatings and process order

Brass, nickel silver and steel do not respond identically to abrasion. Hardness and ductility affect cutting, smearing and edge retention. Nickel silver is a copper–nickel–zinc alloy family, not a statement that a component is made from precious silver. A silver-coloured surface also does not identify the base material because a deposited coating can determine the visible colour.

Rhodium and other specified coatings belong to a separate process decision. They can change appearance and surface behaviour, but they cannot be assumed to correct an incorrectly formed bevel or an uneven decorative pattern. Coating thickness and any required masking must be included in the dimensional plan. Subsequent abrasive rework may remove part of a coating, so its sequence must be agreed before production.

Preserving the removal budget

A practical route proceeds from verified geometry to controlled surface refinement, cleaning and final inspection. Some makers perform a preliminary assembly before disassembly and decoration. The exact sequence depends on the calibre and finishing specification. It should provide a checkpoint before an irreversible removal or coating operation makes correction difficult.

A defect is not always solved by longer polishing. Excess removal can reduce a wall, broaden a bevel or round an edge. If a deep scratch remains, the process must determine its origin and the remaining allowance before repeating a coarser stage. Tools, fixtures and cleaning methods should prevent coarse particles from reaching a later, finer operation.

Record the completed geometry as well as the appearance. A reference part can establish the intended texture and transitions. It should be paired with drawing requirements so that an attractive sample does not silently become permission to change functional dimensions. Repeat production then has two linked targets: a controlled shape and a reproducible visual finish.

Inspection, certification and transfer to other metal parts

Inspection benefits from separate views. Diffuse light makes general texture easier to compare. Directional light reveals scratches and waviness. Magnification helps examine boundaries, recesses and residues. Dimensional and surface instruments answer questions that photographs cannot resolve. Roughness values must be accompanied by the measurement method, direction, filtering and evaluation conditions; one number cannot describe every aspect of a decorated surface.

Geneva stripes and the Poinçon de Genève are different concepts. The former names a decoration. The latter is a certification system with eligibility, component approval and finished-watch requirements. A decorative pattern, brand resemblance or polished screw is not evidence of certification.

The broader manufacturing lesson applies to other visible precision components: define the functional surfaces first, place contrasts deliberately, preserve edges and allow for the complete finishing sequence. Watch cases, small metal covers and visible fasteners can benefit from this planning approach when the material, scale and functional requirements are considered separately. For a production review, the useful inputs are the material, drawing, protected interfaces, finish map, reference sample and intended quantity.