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Every time, the "Experts talking" column develops a different case.
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Presently: Bevelling and finishes in top-of-the-range watchmaking (VIII)

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- Bevelling and finishes...(I)
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- Bevelling and finishes...(VII)
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- Bevelling and finishes...(IX)
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The author

Having acquired an educational background in economics and literature, Caroline Sermier fell in love with watchmaking right from her arrival at Renaud & Papi.
Her current responsibilities as head of the communication department allows her to blend a taste for writing with her fascination for complicated watches, and particularly for the finishing and decorative details on top-of-the-range luxury watches.

19. Bevelling and finishes in top-of-the-range watchmaking (VII): Engraving, Chasing



Certain items of information must appear on the movement for identification purposes.
The maker's mark, the calibre reference number, the various hallmarks as well as personal information may be engraved on the plate, the bridges or the watch case.
Engraving is also used to personalise and enhance the aesthetic appeal of a watch. Motifs may therefore be engraved on a watch for purely aesthetic purposes.

Engraving: the method
Engraving is a decoration performed in relief or by hollowing, by hand or by machine, chemically or by other procedures used on metals such as steel, brass, copper, gold, silver or platinum.
Given the complexity of this work, hand-engraving with a burin is mostly used for one-of-a-kind creations or small series. Skilled engravers must have in-depth knowledge of drawing techniques and the constant practice which is the only way of achieving the required level of skill and dexterity.
Engraving is practised by incising the material using an instrument called a burin or graver. There are several sorts: blade-shaped with two rounded faces, flat with two plate faces and the cutting edge intersected by a third face which thereby broadens the tip of the burin; and gouges which are flat gravers with a groove-shaped hollow.
Industrial engraving
Currently, most engravings such as those for numerals and letters appearing on movements are done by numerically controlled machinery. The engravings are drawn on plans like a part to be machined. The plan is then fed into computer-assisted design software in order to decode the machine language required to execute the path of the tool (engraving-cutter).
Acid engraving
One can also engraving using acid. To do so, the part to be engraved is covered with a varnish sensitive to ultra-violet rays and then placed on a negative film representing the drawing one wishes to engrave. After flattening the film over the part, it is exposed to ultra-violet rays which uncovers the portion that is to be attacked by the acid. The part is then soaked in acid which will only attack that specific portion. Depending on the desired depth of engraving, a particular mixture will be made. Chemical engraving enables the creation of very precise motifs that are only a few tenths of a micron deep.
Pantograph engraving
The letters, numbers or shapes to be engraved are formed on metal plaques or stencils which serves as a guide. They are linked by a leverage system carrying a tool (diamond, burin, milling-cutter) which provides a scale reproduction of the initial shapes, letters, numbers or decorative patterns.
Laser engraving:
A laser beam strikes the matter by bidirectional scanning governed by a programme pre-recorded on a numerically controlled machine. The engraving may be performed by machine for productivity reasons, since the mechanical sped makes the cost price lower.
The style of mechanical engraving is not the same; it can be recognised by its outlines which are flatter and less vibrant than those done by hand, since no machine could ever replace the authenticity of hand craftsmanship.
Moreover, some scrolling effects cannot be done by machine or do not create the same effect, since the precise gestures of the craftsman polish the matter while cutting into it. It is also to touch up machine engraving by hand, using a well sharpened burin to eliminate the mechanical and unattractive appearance which machines may produce.

Chasing is a particularly delicate and spectacular type of decoration generally used for extremely high-end plates, bars and bridges, or on the case itself. It might be seen as a kind of engraving of decorative patterns executed in relief with a bevel-edged steel blade calls a chaser or chisel.
The entire work is done by hammering and repoussť work performed by hand. This type of work calls for dexterity, know-how and a great deal of patience.
Chasing gives an absolutely unique character which simply cannot be reproduced by mechanical means. Currently, stamping has replaced hand chasing. The result achieved is clean and free of burrs.
This mechanical method is suitable for large series and the middle of the range but once again does not permit any aesthetic personalisation.

See: Bevelling and finishes...(VII)




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