A newly published patent offers an unusual glimpse into what Rolex considers a weak point in watch dial production. Nearly every dial receives a transparent finishing lacquer, often made from a material known as zapon, that protects decorative finishes from moisture and oxidation. Rolex says zapon also gives the dial "a depth effect" and highlights its surface finish, enhancing textures such as the sunburst effect on some of its dials.
The problem, according to Rolex, is that the lacquer does not always adhere well enough over time. As the coating ages and is exposed to humidity, its bond can weaken, eventually causing the protective layer to separate from the dial, a process called "décollement" by Rolex. For Rolex, stronger adhesion is "essential for the reliability and robustness" of the dial to "guarantee its longevity over many years."
Instead of reformulating the protective lacquer itself, Rolex engineers found through experiments that inserting an ultrathin layer of metal, like chromium or titanium, between the dial surface and the lacquer improved adhesion "très significativement." Rolex never explained how its engineers came up with the idea of placing a metal layer just a few nanometers thick between the lacquer and the dial. But in accelerated aging tests in its labs, Rolex dials were exposed for three days to 30°C (86°F) and 95% relative humidity before adhesive tape was applied and peeled away. Dials without the metallic layer showed visible "décollement," or delamination, while those with it showed none.
Rolex’s latest invention is another example of the brand's investment in R&D to improve the durability of its watches in ways customers won't notice when they buy them. The metallic layer is invisible to the naked eye and its payoff will not become apparent for decades.