Grenage is a hand-brushed dial finish with a frosted, silvery surface. It is said to give finer detail than other grained dials, while staying much less showy than guilloché. Because it is done by hand, every dial looks slightly different.
How is a grenage dial made?
Urban Jürgensen begins each grenage dial with a plate of solid fine silver. The grained layer is then built up gradually, by hand. A blend of silver, salts and other substances is brushed onto the dial. The craftsperson rubs it in circular strokes in every direction, using special brushes. An electrochemical reaction gives the finished surface its frosted, silvery look. Parmigiani Fleurier treats its dials with a mix of cream of tartar, sea salt, silver and demineralised water.
Where it comes from
Graining began as a practical fix. The grain hid small flaws in the metal surface. The traditional method coated the part with a slurry of gold mixed with mercury. Worries about how toxic mercury is later led watchmakers away from that process. Grained dials are common on antique marine chronometers and table clocks. Michel Parmigiani came across them while restoring old pieces.
Not to be confused with
Shot-peening and graining can both leave metal looking frosted, but they get there in different ways. Shot-peening blasts the surface with tiny metal balls. Graining works the surface with an abrasive brush. Next to guilloché, another dial finish, a grenage dial is far quieter. Its appeal lies in fine surface detail rather than show.
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