--- title: "Grand Seiko Spring Drive and the Art of Zaratsu Polish" url: https://quietmenace.com/watches/grand-seiko-spring-drive-zaratsu/ author: Quiet Menace Editors section: Watches published: 2026-09-08 updated: 2026-09-08 topics: Watch History, Japan, Industrial Design --- # Grand Seiko Spring Drive and the Art of Zaratsu Polish > One engineer spent decades trying to make a mainspring obey a quartz crystal. He died a year before the first one went on sale. Watch the seconds hand on a Grand Seiko Spring Drive and it never ticks. It slides around the dial in one continuous sweep, the visible result of an idea a Seiko engineer named Yoshikazu Akahane had in 1977. It took more than 600 prototypes, some 230 patents and nearly thirty years to reach its finished form. Akahane died in 1998, the year after Seiko first described it in public. ## A mechanical watch with a quartz brain Akahane joined Seiko in 1971 and worked on batteries for quartz watches. That matters, because Spring Drive is an argument with quartz. In 1977, at Suwa Seikosha, he imagined a mechanical watch whose speed would be governed by an electronic circuit, and he called the concept Quartz Lock. The principle is easy to say and hard to build. A Spring Drive starts like any mechanical watch, with a mainspring in a barrel, wound by a rotor or the crown. There is no escapement and no balance wheel. Instead the gear train drives a small rotor called the glide wheel, which spins eight times a second. A quartz crystal and an integrated circuit check its speed once per rotation and apply an electromagnetic brake to hold it exactly on pace. Seiko calls the system the Tri-synchro Regulator. Because the glide wheel drives the seconds hand directly, the hand sweeps instead of stepping. No battery is involved. The mainspring powers everything, including the tiny circuit. ## Twenty years of failure The first prototype, built in 1982, ran for four hours. The IC simply drew too much power, about a hundred times what the final product would need, and the project was shelved. It came back in 1993 with more efficient chips, stalled again, and only in 1997, with components drawing around one hundredth of the earlier consumption, did the numbers finally work. That same year Seiko described Spring Drive in the Journal of the Swiss Society for Chronometry, and in 1998 it was shown at the Basel fair. The first production watches went on sale in Japan in December 1999, limited manual wind pieces from Seiko and Credor, including the Credor GBLG999 and Seiko SBWA002. In September 2004 the first Grand Seiko Spring Drive automatic arrived as the SBGA001, and in 2005 automatic Spring Drive went on sale outside Japan. Current standard calibers are rated to within plus or minus 15 seconds a month, roughly a second a day, with a 72 hour reserve. For Grand Seiko's 60th anniversary the calibre 9RA5 pushed that to five days of power and plus or minus 10 seconds a month, while cutting the movement depth from 5.8mm to 5.0mm. ![A silver wristwatch with a white dial photographed up close](https://images.unsplash.com/photo-1620625515032-6ed0c1790c75?w=1600&h=1067&q=80&auto=format&fit=crop) *Mirror polish only works when the surface underneath is perfectly flat. Photo by Yash Parashar on Unsplash* ## Built in the mountains of Nagano Every Grand Seiko Spring Drive is made at the Shinshu Watch Studio, inside a Seiko Epson facility in Shiojiri, Nagano Prefecture, with views of the Jonen and Hotaka ranges. The site descends from Suwa Seikosha, the same workshop that produced the first Grand Seiko in 1960. Suwa Seikosha became part of Epson through a 1985 merger. The studio makes the movements, cases, dials, hands and indexes in house. In 2000 Epson also set up the Micro Artist Studio at Shiojiri, a small team that builds the brand's most elaborate pieces. The mountain setting is not just brochure copy. Grand Seiko has based dial textures on its surroundings. Its snowflake dial, created in 2005, takes its cue from the snow that covers the Shiojiri area for months each year and from the dial finish of a 1971 Suwa Seikosha watch known as the 56GS. It has become the dial people picture when they hear the name. ## Zaratsu, or why the edges look wet Spring Drive explains the movement. Zaratsu explains why a Grand Seiko case looks the way it does. A Seiko designer named Taro Tanaka wrote a strict set of rules, the Grammar of Design, governing case shapes, indices, hands and dials. The 1967 44GS was the first watch built to it, and the rules still apply. Those rules demand large, flat, angled surfaces with mirror finishes, and Zaratsu is how you get them. A craftsman presses the case against a rotating disc and controls the angle and pressure by eye and by feel, reading heat, vibration and the wear of the abrasive through their fingertips. Done right, the polished plane shows no distortion at all, so a reflection runs across it like a sheet of water. Grand Seiko applies the same finish to the hands and applied indices, which is why the dial seems to flicker as you tilt your wrist. It is slow work that takes years to learn, and Grand Seiko says only a few people in the world have the skill to do it at this level. Most Zaratsu is done on steel and titanium, with gold and platinum cases for the top collections. Seiko's lineage runs through our [Seiko SKX007 diver history](https://quietmenace.com/watches/seiko-skx007-diver-history/) and Casio's very different idea of Japanese toughness in the [G-Shock DW-5000C story](https://quietmenace.com/watches/casio-g-shock-dw-5000c-history/). For the Swiss reaction to quartz, read our [Swatch and quartz crisis history](https://quietmenace.com/watches/swatch-quartz-crisis-history/). Browse more in [watch history](https://quietmenace.com/topics/watch-history/), [Japan](https://quietmenace.com/topics/japan/) and the [watches section](https://quietmenace.com/watches/). Grand Seiko's own [Shinshu Watch Studio page](https://www.grand-seiko.com/au-en/worldofgrandseiko/manufacture/shinshuwatchstudio) and the [Spring Drive entry on Wikipedia](https://en.wikipedia.org/wiki/Spring_Drive) cover the technical detail. Akahane's first prototype, in 1982, ran for four hours. The calibre 9RA5 that carries his idea today runs for five days. --- Filed under: [Watch History](https://quietmenace.com/topics/watch-history/), [Japan](https://quietmenace.com/topics/japan/), [Industrial Design](https://quietmenace.com/topics/industrial-design/) Hero image: Photo by Agê Barros on Unsplash (Unsplash License)