Pressure test (Drucktest)
A laboratory procedure that verifies a watch case's water-tight seal against its rated depth specification. Dry-air or wet pressurisation methods exist. Mandatory step after any case opening and a standard intake check on pre-owned acquisitions.
A pressure test (German Drucktest) is a laboratory procedure that verifies a watch case's water-tight seal against its rated depth specification. It is the only objective way to confirm that a case can withstand its stated water-resistance before the watch is exposed to actual water.
Two testing methods
- Dry-air pressure test. The watch is sealed in a chamber that is pressurised with air. The chamber pressure is monitored after the case is exposed; if pressure inside the case rises (indicating air leaked in), the seal is compromised. Non-destructive. The standard for everyday pre-service and intake testing.
- Wet pressure test. The watch is submerged in water in a pressurised chamber. Pressure is applied, held, and released; bubbles emerging from the case during the release phase indicate compromised seals. Destructive only if seals fail (the watch will let water in); used as the final confirmation test before delivering a serviced watch to a customer who plans to actually dive with it.
A complete service typically uses both: dry-air for the initial check, then wet for the post-service confirmation.
When pressure tests happen
- Before any service-related case opening. Establishes whether the original seal was good (relevant if a customer complaint about moisture is on file).
- After gasket replacement or movement reassembly. The case has been opened and resealed; the test verifies the new seal.
- Pre-owned acquisition intake. Before listing a watch as water-resistant for sale, the dealer should confirm with at least a dry-air test.
- Periodic owner-driven checks. Some owners pressure-test their dive watches annually; manufacturer recommendation is typically every 2 to 3 years for active divers.
Equipment and providers
Pressure-test equipment ranges from basic dry-air testers (€500 to €2,000, suitable for any independent watchmaker) to high-precision combined dry/wet units (€5,000 to €20,000+, used in larger service operations). Most working watch dealers either own basic dry-air testers or partner with a watchmaker who does.
For watches rated above 300m (deep-dive references like the Rolex Sea-Dweller, Omega Ultra Deep, Tudor Pelagos), specialised high-pressure testers are needed; manufacturer service centres are usually the practical option for these.
Documentation and dealer practice
A responsible dealer test-documents pressure-resistance as part of intake:
- Date of test.
- Method used (dry-air or wet).
- Tested pressure level (often expressed in bar or meters).
- Result (pass / fail / partial).
The test record accompanies the watch in the dealer's service-history for the piece. A buyer asking "is this watch actually water-resistant to 100m?" receives a documented answer rather than a verbal assurance.
For dealers who do not perform their own tests, the standard alternative is to disclose the absence: "Not pressure-tested by dealer. Treat as splash-resistant only until tested by a watchmaker."
Related: water-resistance, manufaktur-service, regulation, independent-watchmaker.