Water is, without a doubt, the natural enemy of a watch movement. Whether you are a dedicated diver or simply someone who wears their timepiece in the shower, trusting your watch’s seals is paramount.
One of the most common misconceptions we encounter at W.E. Clark Watch Repairs is the idea that water resistance is a permanent feature. It is not. Over time, rubber gaskets dry out and crack, case metals can corrode, and crowns can sustain knock damage. A watch that was watertight five years ago may not be watertight today.
To ensure your timepiece remains protected, our Lewes workshop is equipped with state-of-the-art testing equipment. But not all testers do the same job. Today, we are looking at the specific role of the Calypso Wet Tester.
The Right Tool for the Job
Before we discuss the Calypso, it is important to understand the hierarchy of testing in our workshop.
For standard pressure testing and final quality control, we rely on high-grade “dry” testing equipment. We utilise the Sigma SM-8850, capable of testing up to 300 metres. This machine uses air pressure and micro-measurements of case deformation to determine if a watch is sealed. It is incredibly accurate and safe because water never touches the watch case during the test.
However, dry testers usually give us a binary result: Pass or Fail.
If a watch fails the dry test, we know there is a leak, but the machine won’t tell us where the leak is. Is it the crystal gasket? The case back? The crown? This is where the Calypso Wet Tester becomes an essential diagnostic tool.
How the Calypso Works
The Calypso allows our watchmaker to pinpoint the exact location of a fault. It relies on a principle of pressure differentials. Here is the step-by-step process of how we use it:
- Preparation: We fill the Calypso’s glass cylinder with water. The watch is attached to a holder and placed inside the cylinder, but crucially, it is suspended above the water line initially.
- Pressurisation: We seal the lid and manually pump a lever, typically raising the air pressure inside the chamber to 3 bar.
- Equalisation: We let the watch sit in this high-pressure air for a moment. If the watch has a leak, this high-pressure air forces its way inside the watch case. The pressure inside the watch eventually matches the pressure in the chamber.
- Submersion: While the chamber is still pressurised, we lower the watch into the water.
- Decompression: This is the vital moment. We slowly release the air pressure from the cylinder.
The Result: Because the pressure outside the watch (in the water) is dropping rapidly, the high-pressure air that is trapped inside the watch tries to escape to equalise.
If there is a leak, a stream of bubbles will furiously escape from the specific point of failure. It looks very similar to finding a puncture in a bicycle tyre. By watching where the bubbles originate – for example, bubbling from the edge of the glass or the winding stem – we identify exactly which component needs replacing.
Diagnosis and Repair
Once the Calypso has revealed the source of the leak, we can dismantle the watch, replace the specific gaskets, seals, or glass, and then re-test.
We generally do not use the Calypso for the final “pass” certification – that is the job of the Sigma or our Lititz Diver 125 – but for diagnostics, the wet test is unbeatable. It allows us to apply a targeted repair rather than guessing where the fault lies.
If you haven’t had your watch pressure tested in the last 18 months, or if you are planning a holiday involving swimming, we highly recommend sending or bringing your timepiece in for an assessment. It is always better to spot a worn gasket on the workbench than to discover it underwater.