Rolex baut Replica Perlmutt Dials
8o Der Begriff "Replica" in einem Rolex Patent.
Zumindest gibt Rolex an, dass sie die Oberflächenstruktur eines Permuttscheibchens replizieren. :D
Ich finde es höchst interessant, welchem Aufwand (Aufdampfen, Plasmadeposition usw.) Rolex betreibt, um eine Metallik-Oberflächenbeschaffenheit auf die Perlmuttzifferblätter zu bekommen.
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In der betroffenen Patentanmeldung (Link) steht folgende Erläuterung:
The timepiece dial according to the present invention may be obtained essentially in two ways, either, preferably, by coating a pre-sandblasted mother-of-pearl sheet with metal, or by producing a replica of a pre-sandblasted mother-of-pearl sheet using a mould, obtained by moulding the mother-of-pearl, as will be explained later.
We will firstly describe the steps of the process that are needed in both cases, namely the means used to reveal the mother-of-pearl morphology, which is normally visible only because of its translucency properties. This is because, if a mother-of-pearl sheet as used to form the visible surface of a watch dial were to be coated, a smooth surface would simply be obtained and all the properties specific to the mother-of-pearl morphology would be lost, which would be of no interest.
This first step consists in subjecting the mother-of-pearl surface intended to form the visible surface of the dial to a sandblasting operation in aqueous medium. The grit used is silicon carbide (SiC) having a particle size varying between 15 and 50 [mu]m, with a mean value of 27 [mu]m. The aqueous suspension is prepared by mixing 1 litre of SiC with 10 litres of softened municipal town supply water (Ganz wichtig: Es geht nur mit Original schweizer Leitungswasser :D ) and 400 g of a gel intended to increase the viscosity of the suspension [...]
The suspension is sprayed onto the mother-of-pearl surface to be treated [...]
This sandblasting operation is followed by a cleaning operation, washing for three minutes with hard water and one minute with soft water, followed by a cleaning operation using an alkaline detergent of 11 pH.
The mother-of-pearl used may be white, pearly white or pink mother-of-pearl, namely Pteria margaritifera or Meleagrina margaritifera from Australia or Japan. The mother-of-pearl may be pink, namely Potamilus purpurata from the USA. Finally, it may be black, namely Pinctada margaratifera from Polynesia.
After the operations of sandblasting the mother-of-pearl substrates in aqueous medium and of cleaning them, it is preferable to coat these substrates with a layer of pure yellow gold (Au), a layer of grey platinum (Pt) or a layer of a pink gold/copper (Au/Cu) alloy. These layers are produced by PVD (physical vapour deposition) under the conditions that will be explained later [...]
The surfaces of the sheets to be coated that are intended to form the visible surfaces of watch dials undergo ion etching. During this etching operation, the target is separated from the work support carrying the mother-of-pearl sheets by a target mask [...]
The target is then etched under the same conditions, the operating power used for the plasma then being 50 W [...]
The parts are cooled by a room-temperature water circuit, the water circulating through the support for the parts to be coated throughout the duration of the deposition [...]
Next, the bias and the plasma are removed, and the chamber cooled by a stream of argon.
The thickness of the deposited layer may typically vary from 100 nm to 1000 nm (i.e. 0.1 [mu]m to 1 [mu]g/m). This thickness is chosen so as to maintain, as faithfully as possible, the mother-of-pearl morphology as revealed by the sandblasting operation. The result obtained may be seen in the appended FIGURE, which relates to a sandblasted mother-of-pearl substrate coated with a 500 nm layer of pure gold.
In a variant of the above process, instead of coating the mother-of-pearl substrate, the mother-of-pearl could be used to produce replicas and these replicas would be coated. [...] To produce these replicas, several methods are possible, especially the techniques of electroforming, ceramic injection and plastic metallization.
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