Swiss luxury watches are works of art that call for protection. A new coating combines scratch resistance with anti-reflective properties while ensuring the distinct residual colour reflection that makes each luxury watch brand unique.
Watch enthusiasts will look at their high-quality dials many times a day. When it comes to protecting the dial of a luxury watch from the challenges of everyday life, sapphire glass is the protective cover material of choice. As a transparent and colourless, flat disc, it can preserve the flawlessness of a watch for many years – thanks, but not least, to its outstanding hardness, which is close to that of a diamond.
Yet sapphire is not completely immune to scratches and chips, and the material reflects twice as much as glass. To meet the demanding requirements of the luxury watch industry in the best possible way, a highly specialized industry has been developing sapphire coatings for decades that reduce scratches to a minimum. However, additional coatings are necessary which not only reduce the reflection but also create the characteristic residual colour that is typical for each watch brand.
It’s exactly this residual reflection that remains one of the biggest challenges in developing a coating for luxury watches. The colour impression should never be yellowish or reddish, as this would suggest an aging effect. The luxury watch manufacturers rather desired a watch glass whose colour perception is freely adjustable and remains durable for a long time. These ideal visions were in part far from what was technically feasible.
SCHOTT researchers saw the possibility of modifying an existing, patented scratch-resistant coating for glass-ceramics also for watches and combined it with an anti-reflective coating. They worked their way towards the specifications of the watch industry and developed corresponding prototypes.
“Our goal was to develop a coating with a colour-neutral residual reflection even after abrasion. This is why we came up with the idea of adapting an existing coating for glass-ceramics.” Christian Henn, Coating Expert & Scientist, SCHOTT Research & Development.
The result of the project? A coated sapphire watch glass that sets new standards for luxury watches in terms of durability and colour fidelity.