1940s Mulco Clamshell Chronograph "Valjoux Cal. 22" Gilt Dial

Though it is widely known that Rolex introduced the first commercially available waterproof watch with the Rolex Oyster in 1926, this innovation was only available in time-only wristwatches. The first waterproof chronograph was invented by Schmitz Frères et Cie, a wristwatch case manufacturer in Grenchen, Switzerland. They submitted a patent (No. 189190) in 1936 for a three-part "waterproof" watch casing design.

This innovative concept encloses the movement within a steel "clamshell," which is then inserted into the upper bezel assembly with lugs secured by four screws. While initially implemented by Fortis in 1937, it was Gallet's version, launched in 1938 and dubbed the "Clamshell", that would become the enduring name associated with this design innovation.

Along with Fortis, Gallet, and the Mulco presently available, the Clamshell case technology was adopted by numerous brands including Breitling, Doxa, Heuer, and Nivada Grenchen. 

With a large-for-its-era 37.5mm case and a perfectly aged glossy gilt dial, this Mulco is an aesthetic powerhouse. Housed in this beautifully preserved representation of early watchmaking innovation is a Valjoux cal. 22 chronograph movement. 

Brand Mulco
Style "Clamshell" Chronograph
Model N/A
Serial N/A
Size Men's
Material Stainless Steel
Dial Glossy Black "Gilt"
Millimeters 37.5
Strap 2pc Handmade Leather Strap



The exceptionally crisp and large case is in downright impressive condition, boasting full, symmetrical lugs that retain original factory proportions with no evidence of over-polishing or warping to the lug holes. The case retains its original small pump-pushers and the unsigned crown is believed to remain original to the watch as well. The case back displays very gentle wear and retains the screws which attach the case components. The watch comes supplied on a 2pc handmade leather strap. 


The original non-luminous glossy gilt dial is a true work of art, showing subtle, yet very attractive aging throughout but with no elements of damage. All of the hands are original to the watch and remain in excellent condition.


None. The watch was recently serviced and is keeping time perfectly. Backed by our 1-year warranty on accurate timekeeping.

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