Stainless Steel Case

Specification

Technical parameters

Overview

A watch case is a pressure vessel with lugs. It has to hold the movement in alignment, accept a crystal and a back with seals, take the crown and pushers through sealed tubes, and survive being worn. Almost every structural decision in a case is a compromise against water resistance.

Stainless steel is the default material because it is corrosion resistant, takes a good finish, and is strong enough to be machined thin. The grades used are chosen for corrosion resistance and workability, and the finish — brushed, polished, or blasted — is applied after machining rather than being a property of the material.

What actually keeps water out is the seal system: gaskets at the back, the crystal and the crown tube, plus the flatness of the surfaces they compress against. A case with a scratched gasket seat will leak no matter how good the gasket is, which is why inspection of the sealing faces matters more than the gasket itself.

What matters about it

• Carries the movement, crystal, back and crown
• Water resistance is a property of the seal system
• Stainless steel resists corrosion and takes a finish
• Sealing faces matter more than gaskets
• Lug width and diameter drive strap and dial choice

Practical notes

• Inspect every sealing face under magnification before fitting a new gasket.
• Check that the case tube threads are clean before fitting a screw-down crown.
• Pressure-test after any case opening — do not assume a resealed case still seals.
• Protect polished surfaces with tape during any work with tools.

Compatible with