Tucked away in the corner of an industrial park in a suburb of Biel-Bienne is COSC. In fact, with no visible branding, logos or signs it takes us multiple laps through the car park to ascertain that we are in fact in the right place. COSC is not deliberately hiding like some secret spy agency which exists but doesn’t exist. It’s more that they don’t need to be publicly visible: if you need to come here you know. And with tens of thousands of other companies' calibres on their premises on any given day, staying out of the public eye has a further real-world benefit. 

This is where time is measured, or rather the ability of watch brands’ mechanical movements to accurately keep and maintain time. COSC, or Contrôle Officiel Suisse des Chronomètres is a unique hybrid organisation – part quasi-governmental, non-profit, independent from the watchmaking industry yet 100% dedicated to it. 

Entry to the hermetically sealed lab is via a double airlocked chamber, lab coats and shoe covers are compulsory. Except for specific high and low temperature rooms the entire lab is keep at constant temperature (23 degrees Celcius) and humidity. Should a power failure occur, emergency systems provide hours of back-up power. Even the separate room where air conditioning units, heating, power, servers and air filtering are located is spotlessly clean and laid out with clinical precision. Only in Switzerland would you find a boiler room clean enough to conduct human surgery. 

As you would expect, the process whereby timekeeping is independently validated is itself an operation which seems to run like clockwork. The laboratory is an exercise in pure functionality. There is no decoration or any attempt to create a trendy, modern ‘campus’ like workspace. Workers process calibres with an efficiency and fast paced workflow: no wonder, they need to test thousands individual movements here every day. Testing runs 350 days per year only pausing for Christmas and scheduled maintenance. Different teams work at weekends (the ultimate student job?)  

The test itself sees uncased mechanical movements without automatic rotors wound and run for 15 days. Special calibrated white COSC dials are fitted allowing calibration to take place. Testing includes running the calibre in five different physical positions and at three different temperatures: 8°, 23° & 38° Celsius (quartz movements are submitted to different test criteria). Watches transferring to the upper and lower temperature ranges must pass through additional double air locked rooms: a direct change in temperature would cause humidity to build up inside the calibre which could later lead to corrosion. 

To complete a very slow test at a very rapid pace COSC has developed its own machines to process, wind and measure accuracy. After each movement is individually checked in calibres are positioned in special COSC designed cases, 15 pieces in each tray. COSC has developed a special winding machine which can deliver a full wind to any mechanical movement in a matter of seconds.  

How is accuracy measured: using cameras, in-house developed software and plenty of mathematics. COSC measures the angles of the hands optically and their software can measure any deviation in timekeeping. Three atomic clocks are used to deliver the ‘correct’ time for referencing. Before the advent of digital cameras analogue films, prints and scanning were used to provide a similar albeit very manual process.  

Speaking of manual, there is one type of movement which still requires a much more hands on approach – one that is very close to HORAGE’s heart! Tourbillons. The absence of a seconds hand means the optical systems developed by COSC cannot function. Tourbillon calibres are therefore tested in a more manual way, whereby employees are required to start and stop calibration themselves. No surprise then that only a few select staff members with incredibly rapid and consistent reaction times are certified to carry out these tests. 

COSC keeps a digital database of every tested calibre for 10 years: a literal library of mechanical watchmaking unlike any other testing institute. Three labs using identical machines, software and processes are in Biel & the Jura region of western Switzerland to serve the industry “close to our customers.” 

In today’s world of multiple different testing protocols such as METAS which tests a watch through its entire production some may say that COSC is old fashioned, it “only” tests raw calibres, not the whole watch head. This ignores one simple fact: to pass COSC chronometer accuracy a brand must first attain a very high level of accuracy. This hurdle is therefore also a guarantee of quality (and is pre-requisite for use of the word chronometer and other test protocols such as METAS). 

The COSC testing process and value is dependent on a unique mix of highly skilled, yet manual labour supported by specialist custom testing equipment and software. There is no wasted effort to be seen here: a relentless workflow comprising of millions of individual steps keeps this machine ticking. Who’d have thought that a few hundred humans could so perfectly emulate the parts of the mechanical engine that they check, day-in, day-out 

Tick, tock, tick, tock, tick, tock…… 

Thanks to Silvan for showing us round the COSC facility. 

Footnote:

Since we visited COSC a new certification standard has been announced. This updated protocol is an optional addition, testing a cased watch at a slightly higher rate of tolerance test as well as introducing non-timekeeping parameters e.g. power reserve verification, magnetic resistance at 200 Gauss (a level which our products far exceed by thanks to the use of a full silicon escapement).