In recent years, "new materials" have become widespread in the watch market. The use of unconventional materials for the exterior and movement of watches has brought about major changes not only in terms of design, such as shape and color, but also in performance. Issue 112 of Chronos Japan featured such "new materials" as "New Materials That Have Changed Watches," and we are republishing this article on webChronos. This time, we will look at three leading watch manufacturers that have used structural colors to create new dial expressions.
Photographs by Takeshi Hoshi (estrellas), Yu Mitamura
Masamasa Hirota (this magazine): Interview and writing
Text by Masayuki Hirota (Chronos-Japan)
Edited by Hiroyuki Suzuki
[Article published in the July 2024 issue of Kronos Japan]
The ultimate trump card for vibrantly colored dials
Since around 2015, dials have become a genre that many manufacturers have been working on. First, polished lacquer dials became popular, then gradient dials, and in recent years, unprecedented color expressions have been in demand. The key to this is not plating or lacquer, but the attempt to "express new colors using structural color."
Dial expression evolves with new technology
This model uses CVD processing, a type of thin film formation method, on the dial. By skillfully using structural colors that change color with the interference of light, it is possible to achieve a color similar to Paraiba tourmaline, which is difficult to achieve with plating or painting. The thin coating also makes it suitable for guilloching. Automatic winding (Cal. C. 6004). 28,800 vibrations per hour. Power reserve of approximately 55 hours. Stainless steel case (diameter 42 mm, thickness 14.5 mm). Water resistant to 10 bar. Limited to 50 pieces. (Inquiries) Eiko Watch Tel. 03-3837-0783
In the past, dials were colored either by plating or paint. The standard method was to paint for black and electroplating for silver. Plating has a thinner film than paint, allowing the delicate finish of the underlying surface to show through. However, because the color is not stable, manufacturers experimenting with new colors preferred thick paint finishes rather than plating.
This situation changed dramatically in the 2010s. As the boom in luxury watches accelerated and more money could be spent on exteriors, manufacturers began to seek new expressions in their dials. As a result, lacquer dials gained depth, and plated dials added a variety of colors. This was followed by physical vapor deposition (PVD). This has a thinner coating than paint and offers a wider range of colors than electroplating. While previously considered color stability unstable, improvements in color reproduction have led to widespread adoption. Audemars Piguet has adopted blue PVD dials for some of its Royal Oaks, and Omega has also begun incorporating PVD dials into its latest models. The same can be seen in the vibrant blue dial of the Casio Oceanus. Even Rolex has adopted a PVD finish for its latest ice blue dial, rather than a plated one.
This new model features a very thin ALD coating on the dial. The vibrant pink color is something that could not be achieved with conventional PVD. Structural colors change color depending on the light, but in recent years, it has become possible to achieve stable color development. As the photos show, the finish is superb. Automatic movement (Cal. 5800). 28 jewels. 28,800 vph. Power reserve approximately 50 hours. 18KPG case (diameter 34mm, thickness 8.8mm). Water resistant to 50m. (Inquiries) Audemars Piguet Japan Tel. 03-6830-0000
An evolution of this approach is the dials we've seen in recent years, which feature thin optical multilayer coatings layered using CVD (ALD) processing. While the details are unclear, what they have in common is that extremely thin optical coatings are layered together and their structural colors are used to express color. The principle is the same as the rainbow colors seen in soap bubbles and CDs, but the color-producing method is completely different from conventional methods. Specifically, by layering multiple thin coatings and controlling their thickness, various wavelengths of light interfere with each other, resulting in the appearance of color. This makes it possible to express colors never before seen. Another benefit is that the degree of optical interference changes as the viewing angle changes, altering the color, adding depth to the dial. Additionally, because this optical multilayer coating is extremely thin, it doesn't obscure the underlying expression of the dial. In other words, it's designed for high-end watches.
Chronoswiss is the one that has put this dial front and center. The Delphis Paraiba attempts to recreate the color of Paraiba tourmaline using optical multilayer coating. Not only is the color vibrant, but the delicate guilloched finish is also preserved. Audemars Piguet has also adopted this finish for its purple and pink dials, combining guilloched finish with unique colors. Incidentally, there are currently several suppliers in Switzerland that can perform this finish, and there are also dial manufacturers that handle everything from dial manufacturing to the deposition of optical multilayer coating.
Japanese manufacturers are not far behind. Orient Star's new "M34 F8 Date" will be using optical multilayer coating in 2024. Seiko Epson, the manufacturer, has recently begun to produce some of the dials in-house. This makes it easier for them to apply their technology. The company specializes in extremely vibrant lacquer dials, and the new optical multilayer coating reproduces vibrant blue without obscuring the base.
Following Citizen, Orient Star has also achieved structural color using its own technology. The dial, made at Shinshu Toki no Takumi Kobo using Seiko Epson's optical multilayer film technology, is made of multiple layers of nearly colorless nano-films. The vividness of the color is outstanding. Automatic winding (Cal. F8N64). 22 jewels. 21,600 vibrations per hour. Power reserve of approximately 60 hours. Stainless steel case (diameter 40mm, thickness 12.9mm). Water resistant to 10 bar. (Inquiries) Orient Customer Service Tel. 042-847-3380
