The Bench · N° 07

Anglage, perlage and black polishing explained

These finishes treat different surfaces for different visual effects. Their quality is visible in edge shape, consistency and preparation, not simply in the presence of a familiar name.

Hen & Mills Editorial · 4 min read · 15 August 2026

Anglage, perlage and black polishing are three distinct movement-finishing techniques. Anglage bevels and polishes component edges. Perlage applies overlapping circular marks to flat surfaces. Black polishing creates an exceptionally flat reflective face.

They are often discussed together because they appear in finely finished movements, but they demand different tools and judgement.

The names identify the process. Execution determines the quality.

Anglage

Anglage removes the sharp corner where the top and side of a bridge or lever meet. The resulting bevel is then smoothed and polished.

A good bevel has a consistent width, a clean reflective surface and deliberate transitions around curves and corners.

It can make the component safer to handle and remove burrs, but its elaborate visual form is primarily decorative.

Interior angles

An acute inward corner is difficult to finish with a rotating machine because a round tool cannot reach the point cleanly.

Traditional hand-finishing uses files, stones, abrasive sticks and polishing tools to create a sharp meeting of bevels.

For this reason, crisp interior angles are often used as evidence of manual work. Their presence still needs close inspection; a decorative notch is not automatically a true finished angle.

Rounded and flat bevels

Some makers prefer a flat bevel with a sharp line at the top surface. Others create a rounded, bombé profile that rolls through reflected light.

Both can be demanding when carried out consistently.

Comparisons should account for the intended style rather than assuming one shape is always superior.

Perlage

Perlage consists of small overlapping circles applied with a rotating abrasive peg or brush. The operator lowers the tool onto the surface, lifts it and repeats the mark in rows.

It is common on baseplates, recesses and areas partly hidden by bridges.

Regular overlap and placement create an ordered field. Random circles without consistent depth or spacing look very different under magnification.

What perlage does visually

Each circular mark contains fine abrasion that catches light from several directions. Overlap breaks up a broad plain surface and makes minor visual changes less obvious.

Claims that perlage primarily traps dust or improves oil retention overstate its functional role. It is a decorative surface treatment.

Its use on hidden areas can show that the maker chose to finish parts beyond the immediate display-back view.

Black polishing

Black polishing, also called specular or mirror polishing, aims to make a steel surface extraordinarily flat and smooth.

Under one lighting angle, the surface reflects light directly and appears bright. Tilt it away and it can appear deep black because it reflects a dark environment rather than scattering light.

No black pigment is applied. The effect comes from flatness and controlled reflection.

How black polishing is done

The component is worked against a very flat surface with progressively fine abrasive, traditionally including diamantine on a zinc or tin plate.

Pressure and movement must remove high points without rounding edges or introducing waves.

Small steel parts such as screw heads, cap pieces and tourbillon bridges are common candidates because maintaining perfect flatness becomes harder as the area grows.

Preparation decides the result

A final polish cannot rescue poor geometry. Filing, stoning and pre-polishing establish the shape before the reflective surface is attempted.

Scratches from an earlier abrasive stage can reappear under strong light. Rounded holes and softened corners reveal careless handling.

The finest-looking surface is the end of a sequence, not one quick pass.

Machine and hand work

Machines can produce excellent repeatable decoration, and hand-controlled tools can produce poor work. The meaningful distinction is what control and finishing challenge the component required.

A uniform machine bevel on an accessible edge is different from a sharp interior angle formed and polished individually.

Brands should describe hand finishing with enough detail that the claim can be understood.

Decorative coherence

A well-finished movement coordinates bevels, stripes, perlage, graining, screw treatment and plating. One highly polished component cannot compensate for rough edges elsewhere.

Look at transitions around jewels, countersinks and bridge ends. Consistency across small, awkward areas often reveals more than the large surfaces designed for photography.

Decoration should support the architecture rather than cover it with unrelated effects.

Can finishing improve function?

Removing burrs and creating correct surfaces can support assembly and reduce contamination. Flat functional faces, pivots and teeth also require careful finishing for performance.

Decorative anglage and perlage, however, should not be confused with the functional finishing of bearing and contact surfaces.

A movement can be mechanically excellent with restrained decoration, or visually elaborate without exceptional timekeeping.

Service risks

A slipped screwdriver can mark a polished screw or bridge. Aggressive cleaning can alter plating, and careless refinishing can remove original geometry.

Restoring black polish or a matched bevel demands the same control as creating it. Repeated work also removes material.

A service centre's handling standards matter when the movement's finish contributes significantly to its value.

How to judge photographs

Strong directional lighting makes polished edges and black-polished parts dramatic. It can also hide unevenness outside the chosen angle.

Look for images from several directions and at high enough resolution to see edge lines and surface consistency.

Remember that dust on a macro photograph is not the same as a finishing defect, while rounded geometry cannot be removed by cleaning.

Three different jobs

Anglage shapes and brightens edges. Perlage organises flat backgrounds with overlapping circles. Black polishing makes a surface flat enough to switch from bright to dark as the light changes.

Each can be applied at different levels of care.

The most convincing movement does not merely contain all three names. It shows that the maker understood where each finish belongs and executed it cleanly across the entire calibre.