Complete glossary of watchmaking terms related to gaskets, water resistance and watch repair. A reference for amateurs and professionals.
O-ring
Definition : sealing ring with a circular cross-section (torus shape). The most common material is nitrile (NBR) or silicone. It provides a static seal between two parts by deforming under compression.
See our selection of O-rings.
Flat gasket
Definition : gasket with a rectangular or trapezoidal cross-section. Used mainly for buckles and crimped or snap-on case closures.
See our selection of watchmaking flat gaskets.
Red gasket
Definition : tinted-red silicone gasket, specific to mineral and sapphire crystals. Its stiffness keeps the crystal in place under bezel pressure.
See our selection of red gaskets.
Crown
Definition : winding and time-setting component of a watch. Its stem passes through the case; a cylindrical gasket seals between the stem and the tube. A screw-down crown adds a thread for reinforced sealing.
Case
Definition : shell containing the movement, dial and hands. Three interfaces are concerned by sealing: the crystal, the case-back and the crown (and possibly the pushers).
Bezel
Definition : ring fixed above the crystal. Crimped, screwed or clicking, it may carry a graduation (diving, tachymeter).
Screw-down case-back
Definition : rear cover of the case held by a thread. More water-tight than snap-on backs but requires a dedicated wrench to open.
ATM / bar
Definition : unit of pressure. 1 ATM = 10 m of static water depth. A 5 ATM watch withstands 50 m static (but not active diving: tolerates shower / surface swim).
IPX rating
Definition : Ingress Protection code against water. IPX7 = 1 m / 30 min immersion; IPX8 = prolonged immersion at a depth specified by the manufacturer.
Silicone grease
Definition : water-repellent lubricant used to maintain watchmaking gaskets. Preserves their suppleness and sealing ability. Apply in a thin layer.
See our selection of watchmaker silicone grease + the guide lubricate a gasket.
Tweezers
Definition : fine-pointed pliers for picking up tiny parts. Indispensable for handling gaskets without deforming them.
Watchmaker loupe
Definition : loupe mounted on a stand or held to the eye. Usual magnification: x10. Lets you inspect gaskets for cracks, crushes or wear.