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Contents
- O-rings in watches and why they are important
- NBR and EPDM O-rings in watches: properties and applications
- O-rings in watches provide a watertight seal
- Maintenance and replacement of O-rings in watches
O-rings in watches and why are they important?
O-rings are small but essential components in watches that provide a secure seal between the different watch parts. They form a flexible barrier between the watch case, crystal and crown, preventing dust, moisture and small particles from reaching the delicate movement. Without a proper seal, mechanical and quartz watches can suffer damage within a few months. This makes O-rings important not only for waterproof models, but also for everyday watches exposed to perspiration, rain and dust. Regularly checking these sealing rings prevents leakage and significantly extends the service life of the watch.
NBR and EPDM O-rings in watches: properties and applications
The materials NBR and EPDM are commonly used for O-rings in watches. NBR is known for its excellent resistance to oil, grease and mechanical wear, making it ideal for watches with metal components and moving crowns. EPDM, by contrast, offers better resistance to UV radiation, ozone and extreme temperature fluctuations. This material is often used in sports and diving watches worn outdoors or in wet conditions. Manufacturers select the type of O-ring according to the function of the watch: NBR for robust everyday models and EPDM for water-resistant watches or watches intended for extreme environments.
O-rings in watches provide a watertight seal
The main function of an O-ring is to create a reliable watertight seal. Even small installation errors can cause condensation or leakage, which may permanently damage the movement. Diving watches often use multiple EPDM rings in the crown and case back to ensure pressure resistance at depths of several tens of metres. Water resistance is not only important for sports applications. Everyday activities such as washing your hands or being caught in the rain can also cause damage if the seal is not functioning correctly.
Maintenance and replacement of O-rings in watches
O-rings gradually lose their elasticity and may crack, harden or deform. A watch enthusiast can easily check the condition of the sealing rings by looking for visible wear or by having the water resistance tested by a watchmaker. Regular maintenance, such as replacing the O-ring during a battery replacement or service, prevents moisture from entering and significantly extends the service life of the movement. Tip: EPDM rings can last for decades in a dry watch, while NBR wears more quickly when exposed to oil or sunlight.
FAQ
An O-ring is a circular rubber ring used to seal the gaps between components of, for example, a watch. You usually find them around the crown, the case back, or beneath the crystal.
The most commonly used O-rings in watches are NBR (nitrile rubber) and EPDM. NBR O-rings resist oil and wear, whereas EPDM O-rings offer better resistance to UV radiation, ozone, and water. The choice depends on the type of watch and the intended use.
O-rings in watches lose their elasticity over time and can crack or deform. Symptoms include reduced water resistance, condensation under the crystal, or visible wear on inspection. Regular maintenance prevents the movement from being damaged due to a damaged O-ring.
It’s recommended to check O-rings during every service or battery replacement. With daily use or exposure to water or sunlight, replacement may be needed every 3–5 years, depending on the material.