Gasket
A rubber or synthetic O-ring seal that makes the watch case resistant to water and dust.
What is a Watch Gasket?
A gasket is a compressible seal — typically an O-ring made from nitrile rubber, silicone, or a synthetic compound — that sits between the mating surfaces of watch case components to prevent water, dust, and air from entering. Without functioning gaskets, even a watch rated to 100 meters can leak from a light splash.
Where Gaskets Are Found
A typical watch has gaskets in three locations:
- Case back gasket — seals the case back against the middle case
- Crown tube gasket — seals around the winding stem where it exits the case; this is often the most vulnerable point and a common entry point for moisture
- Crystal gasket — on many watches, a thin gasket or cement ring seals the crystal into the bezel
Gasket Replacement
Rubber gaskets degrade over time — they compress permanently, dry out, crack, and lose their sealing ability. This happens faster with heat, UV exposure, and chemicals (chlorine, solvents, sunscreen). For this reason, gaskets are routinely replaced at every service, even if the watch has not been submerged. After gasket replacement, water-resistant watches are pressure-tested with a specialized device to confirm the seals hold.