The range and richness of the colours that adorn Rolex watch dials are the result of a mixture of high-level physics, exquisite judgement and pure chemistry – all mastered in-house.
At the heart of a Rolex laboratory in Geneva, card-shaped sheets of metal with colourful, rough dabs of lacquer stand out in sharp contrast to the orderly grey and white surroundings: they betray the first attempts to conjure up a new hue for the myriad selection of watch dials.
Although the technician, his spatula and tubes of paint often form the starting point of the search for new colours, these swatches are merely superficial signs of an exacting skill and science. One that demands command of cutting-edge surface physics and chemistry as much as mastery of a palette of paints: a blend of creative flair and, increasingly, space-age technology, where the naked eye nonetheless remains the final judge of what colour may grace a Rolex dial.
The alchemy of dial colours at Rolex draws on ancestral techniques as well as on 21st century science: from classic enamelling or lacquering, to electroplating or highly advanced thin-film technology using plasma torches or electron beams to coat the dial. This allows for an immense array of dial tints: each more complex technique brings a richer finish to the brass disc that serves as the foundation for most of the watch faces.
Lacquer provides a huge choice of opaque colours, predominantly used for black and for white. Electroplating creates metallic colours based on real metals, while ever more sophisticated PVD (Physical Vapour Deposition) techniques coat the disc with an infinitesimally thin film of molecules producing even more luxurious colour and visual depth. Final varnishes and surface treatments such as fine bead blasting may add gloss, matt and other finishes, subtly changing the surface texture and appearance of the same hue.
As a result, a near infinite spectrum of colours and shades is technically possible at Rolex, without counting more sophisticated or patterned dials made with mother-of-pearl, meteorite. It often takes a qualified chemist or physicist to know which avenues to explore for a particular colour requested by the designers – and at least three months of laboratory research and trials to produce the required shade.
In rare instances these alchemists of colour are ready to spend years trying to satisfy an exclusive request for a perfect match. Some colours also vary in tune with fashion and tastes. In the 1980s and 1990s, the hue of the classic Rolex champagne-colour dial was changed several times, gaining in warmth and pinkness before it retreated to greater subtlety. Ice blue, another distinctive Rolex colour, has also varied over the years. But one of the biggest challenges the colour magicians face is the initial request from the design department and how to turn that wish into reality, due to the sheer breadth of hues that can be produced using the three basic methods to colour the dial blanks. The science is such that the developers may also propose new hues as they explore and discover the full range of possibilities that the latest PVD techniques have to offer. And their assessment will even take into account how the appearance of the dial colour will vary slightly on the wearer’s wrist, under the prism of the watch’s sapphire crystal.
Tinted opaque lacquer conjugates almost limitless freedom of colour with intensity and a smooth finish. Although the basic colours are based on standardized Pantone colour charts, Rolex creates its own tints, which are also carefully referenced so that they can be reproduced exactly each time. Lacquering remains the only way to produce a pure white dial and is also used predominantly for black, typically on the Submariner’s dial.
Once the most noble form of coating, electroplating emerged in the first half of the 19th century in Europe as a means of producing silverware as well as gold-plating. In watchmaking it is the predominant method of achieving pure metallic colour dials. Silver-plating is mostly used as a base layer for the sunray finish, where further colour is added to the prepared dial. Sometimes colours such as champagne-colour are achieved through electroplating with more than half a dozen different metals, hinting at the added complexity of the technique.
Shades and tones can vary according to an immense range of variables, such as the metals used, the temperature of the electroplating baths, the immersion time of the dial blanks, the intensity of the electric current used in the electrolysis – and the combination of each of these. This complicates the search for an exact hue and, like PVD, makes it a job for those with a potent background in applied science as well as a keen eye.
PVD is directly derived from thin film technology developed originally by NASA for its space programmes. This highly versatile technique allows intense colour to be added to metallic finishes by mixing virtually any inorganic material with metals. It can produce an infinite range, expanding the spectrum obtained from electroplating with luxurious tones.
Often carried out inside sophisticated vacuum chambers where the pressure is equivalent to that found in space, some 150 kilometres above the earth’s surface, the techniques used by Rolex coat the dials with a fine layer of vaporized oxides and metals less than one micron thick. The eye can capture different reflections and hues on a PVD dial from different angles, yet distinguish astonishing depth in its intense sheen.
Two techniques stand out amongst those used in-house: thermal evaporation which uses an electron gun to vaporize the source material; and magnetron sputtering, which is based on the ionization produced by a plasma torch. PVD coatings are very adhesive and hard, and can be controlled with great precision, almost layer by layer of atoms. But the process is also highly sensitive to the slightest speck of dust, and all the PVD colouring operations are carried out in clean rooms. In harnessing such sophisticated technologies and skills in-house and on such a scale, Rolex is an exception in watchmaking.
Enamelling is one of the most highly-prized and classical colour finishes, whose origins can be traced back to the 13th century. At Rolex, enamelling is used to form the hour markers on sumptuous diamond-paved jewellery dials made from gold.
From silica-based mineral and coloured metal oxides ground to a fine powder in a mortar and pestle, enamellers handcraft bright, intense colours, producing a vitreous, scintillating finish after the dials are glazed at temperatures of 800–950 °C in a kiln. It is a long and meticulous process, sometimes carried out patiently layer by layer for the right effect. Only a small number of such dials are made by Rolex enamellers each year with infinite precision. They grace some of the most beautiful jewellery watches made by the brand.
Final surface finishing can alter the appearance and texture of the dials significantly. Even a simple black gains a sporty appearance with a matt varnish while gloss varnish will give the same black a more refined and elegant look. Colours are studied under three standardized lighting conditions: those prevalent in a shop window, under natural outdoor light and indoors.
Ultimately, despite the advanced technology mobilized in its creation, the judgement and approval of the new tint for a dial will be eminently human.
For, with thousands of colours already identified at Rolex, even colour spectrometers that measure light cannot distinguish between each shade, hue and tone – let alone beauty – with the same finesse as the human eye.