GRAINING

Graining is the operation, and its result, consisting of giving grain — a regular, matte and slightly raised texture — to a smooth surface, with a view to finishing or subsequent treatment. Applied to the bridges, to the Main plate, to dials or to certain external parts (case, dial, hands), it creates a grainy finish that catches light diffusely rather than specularly. Historically obtained by rubbing with a fine metal brush, sometimes assisted by a mordant, graining is nowadays mainly carried out by Sandblasting or Shot blasting (micro bead blasting) — projection of abrasive particles under pressure — as well as by Engraving mechanical processes, methods offering a more regular and reproducible grain in series production. The fineness and homogeneity of the grain depend on the particle size of the abrasive used and the machine settings. Graining fulfills a dual function, decorative and technical: it unifies the appearance of a surface, conceals any machining irregularities, and frequently serves as a contrasting background against which beveled edges and polished surfaces stand out. It is distinguished from Circular graining, formed of tangent concentric circles, and from Sunburst finish, with rectilinear striations radiating from a center.