What we consider normal today - a watch that is braced for wind, rain and washing hands - is the result of many decades of perfectioning the concept of the 'waterproof' watch. Over the decades several companies, case makers and inventors dedicated their work to defy the elements and 'defeat' a mechanical watches most dangerous enemy: Humidity. One particular category of watch constructions enabled tightly sealed cases by fixating screws - the so-called clamped cases. How do they work? Who made them famous? And why aren't they around anymore?
October 30, 2024
Clamshells, Oysters & Sealed Cases - Waterproof Watches of the 1930s (Part I)
Marcus Siems @siemswatches
Collector, Author, Data Analyst
I would like to begin with a quote from a 1956 advertorial:
- It was in 1926 that Rolex invented the Oyster case, the first truly waterproof* watch case, a revolution in the history of watchmaking. - Rolex
And this or similar statements are probably engrained in the minds of many collectors and enthusiasts. A statement that seems to have been perpetuated at least since the 1950s. However, Rolex and their Oyster case was neither the first nor the only water-resistant cases at the time (For a quite exhaustive overview of that early history see also [here]).
What we easily forget is that already around the beginning of WWII over four dozen different approaches to seal a wristwatch against the elements existed. Let that soak in for a second...
A 1956 Rolex advertorial for the 30th anniversary of the Oyster case design. The description under the ad reads that the Oyster was the 'first truly waterproof' wristwatch. A statement perpetuated by Rolex ever since but arguably not true*. Advertorial Courtesy of HIFI Archiv.
What we consider normal today - a watch that is braced for wind, rain and washing hands - is the result of many decades of perfectioning the concept of the 'waterproof' watch. Over the years several companies, case makers and inventors dedicated their work to defy the elements and 'defeat' a mechanical watches worst enemy: Humidity.
During the 1940s waterproof watches came basically in four flavors. First, case-backs that were screwed into the case (like the Borgel cases or the Rolex Oyster), second, an inner watch encased in an outer second case (Gruen/Finger patents or the Omega Marine), third, two-part cases with pressure applied gasket, and lastly, watch cases that were fixated by screws.
And this last category - the clamped cases - is the one we're focusing on! How do they work? Who made them famous? And why aren't they around anymore?
1) Clamped Watch Cases & Two Brothers
Backside of a Schmitz Freres patented waterproof case with screws behind the lugs to keep the case back sealed to the upper half - the so-called 'Clamshell'. Photo Courtesy of Vintageur.
What appears alienating today was hot technology during the 1930s. What you can see here is the the case back is tightly sealed and held in place by screws behind the lugs - through the so-called 'Clamshell' case design. And the two unsung heroes who were pioneering this style were the brother Otto and Werner Schmitz**.
The two brothers established their business during the 1930s in Grenchen (Switzerland) and were the driving force behind several case designs and related patents between 1934 and 1944 ([here], [here], [here], [here], [here], & [here]).
A 1940s advertorial for the manufacture Schmitz Freres from Grenchen and their watch cases. Advertorial Courtesy of HIFI Archiv.
2) The 'Clamshell' & Early Waterproof Chronographs
Ok so how does it work? The most important patent from the two brothers probably is the CH189'190 - exactly that patent that describes the construction of the aforementioned 'Clamshell'. Hereby, four screws clamp the case-back to the upper half of the case. Interestingly, the patent states three different ways to do so: Either insert the screws vertically, horizontally, or at a 45 degree angle (the most common application).
The Swiss patent No. 189190 - filed in 1936 and registered in 1937 - depicting the construction of the 'Clamshell': A screw-based system to tightly seal the watch case. Photo Courtesy of David Boettcher at Vintage Watchstraps.
This particular design is - out of the many registered patent - also the best known among collectors. Gallet - one of the oldest Swiss watch- and clock-makers - acquired the patent from the Schmitz brothers in early 1937 and started to produce one of the world's first waterproof chronograph watches - the Multichron 30 - in 1939 (maybe even The first depending on what truly waterproof means).
Ultimately, the design was further adapted for chronograph pieces from Heuer, Breitling, Tavannes/Cyma, Record, Eterna and many more.
34mm of greatness: A 1940s Gallet Multichron 30 chronograph with 'Clamshell' case and black snail dial. Photo Courtesy of Wind Vintage.
3) The Crab Claw(?) - The Rectangular Solution
Chronograph collector's probably knew about the 'Clamshell' before but have you heard about the 'Crab Claw' case? Probably not because I decided to come up with a name that fits the 'seafood buffet' theme of the discussed designs. Anyhow, what I mean by 'Crab Claw' is another Schmitz design often found in rectangular time-only watches and predominantly from Cyma and Tavannes (Swiss patent No. 235'809).
These pieces come with a two-part case construction that is stuck together and clamped with two T-like parts at the top and bottom of the case... Meet the rectangular 'Crab Claw':
What is only a footnote in modern horology was a strike of genius during the 1930s. The Schmitz brothers and others revolutionized the construction of waterproof watches. Just like this rectangular 'Watersport' from Tavannes (left & top) along with the relevant patent (right). Photos Courtesy of Uhrforum.
4) Conclusion & Collectability
History is written by winners. Today, we mainly know the classic screw-down case backs with gaskets as means to protect your watch from the elements. And that's even though so so many other designs existed. This is in parts probably due to the success of Rolex's Oyster and Borgel designed blueprints originating in the 1920s.
But the 'seafood buffet' was full of options and workarounds during the 1930s. The 'Clamshells', the 'Crab Claws' and the 'Marines' of their time were interesting, new and thought provoking concepts that creatively worked around existing patents and tried to establish their own brand with (partially incremental) improvements to existing structures.
A 1940s advertorial from Gallet for their 'Clamshell' chronographs. Advertorial Courtesy of Fratello & Gallet World.
In 1941 already 55 different approaches*** to waterproofing your watch existed for Switzerland alone: 1 sealing an inner case within and outer one, 9 gasket-only, 13 clamshell-esque, & a whopping 32 screw-down case-backs (with and without gasket). Clearly, the screw-down case-back was already the frontrunner for the race to waterproof excellence.
But besides the late start are there other reasons why the 'Clamshell' design didn't stick? Well, I'm probably not technically versed enough but my guess would be that technology might not have been the only reason... Maybe it was the design itself? Did people that were accustomed to sophisticated Artdeco timepieces appreciate visible bolts and screws on their watches? Maybe not as this has been a trend that would come up a good 35 years later again...
Visible screws have been more a thing of the 1970s & 80s... Photos from Goldammer Shop.
After the buffet was eaten up the screw-fixated case constructions for 'truly waterproof' watches remained a mere footnote in horological history. The visible screws weren't popular enough to become the most important player of the upcoming 100 years.
However, these pieces still deserve their rightful place among the all-time greats. Let's not forget that the Gallet Multichron 30 was one of the very first 'truly waterproof' chronographs****! And it may not be the 'Oyster' but the 'Clamshell' itself is probably more popular than most of the 31 non-Rolex screw-down cases from 1941...
What an achievement for two brothers from Grenchen, Otto & Werner Schmitz.
A design that's up there among the all-time great chronographs and one of historical importance. Photo Courtesy of ShuckTheOyster.
A big thank you goes out to Jacob Hillman (@hilman.watches) for providing important pointers and insights on the Schmitz patents.
Footnotes
* Well, you got to be devil's advocate to pin down what 'truly waterproof' actually means...
** Other pioneers in this particular field with registered patents were Henri Colomb (for Tavannes) & John Simon.
*** And potentially more!
**** As long as you didn't pump the pushers underwater...
