A Watch Is A Movement, A Case Seal And A Strap That Goes First

A watch is bought for what is inside it and lived with through what is outside it. The movement determines accuracy and service intervals, while the case seals and the strap determine almost everything an owner actually experiences.

Movements divide into two families

A quartz movement uses a vibrating crystal as its time reference and a small motor to advance the hands, which makes it accurate, cheap to produce and dependent on a battery.

A mechanical movement stores energy in a wound spring and releases it through an escapement regulated by a balance wheel, which is a mechanical oscillator with far lower inherent accuracy.

The premium attached to mechanical movements is therefore not about performance. It reflects finishing, assembly labour and the fact that the object can be serviced indefinitely rather than replaced.

Water resistance is a pressure test, not a depth

Ratings are expressed in depth units but derived from a static pressure test, and swimming or washing generates dynamic pressures far above the static equivalent of the same depth.

The seals doing the work are small gaskets at the caseback, the crown and the crystal, and they are elastomers that harden and take a set over the years.

This is why water resistance is a maintenance property rather than a permanent specification, and why any case that has been opened has had its seal disturbed.

The crown is the weakest point

Every other opening in the case is sealed once and left alone, while the crown is a shaft that passes through the case and is pulled and turned by the owner.

Screw-down crowns exist to compress the gasket properly when closed, and a crown left unscrewed removes the protection that the rest of the case was built around.

Grit drawn in along that shaft is also the commonest route for contamination to reach a movement, which is why cases opened in dusty conditions cause problems later.

Straps and bracelets are the real consumable

Leather absorbs perspiration and breaks down at the fold points, and no amount of care prevents that because the material is being flexed while chemically attacked.

Bracelets wear at the pins and at the holes they run through, which produces the stretch that owners describe as the bracelet becoming loose over years.

Spring bars are the small components that attach either type, and they are the cheapest part of the whole object and the one whose failure loses the watch entirely.

Servicing is scheduled by lubricant, not by fault

Mechanical movements rely on tiny quantities of oil at high-load pivots, and those oils migrate and degrade over a period of years regardless of how much the watch is worn.

Running a movement with degraded lubricant transfers wear onto the pivots themselves, which converts a routine service into a parts replacement job.

Whether those parts remain available for a given movement is the question that decides long-term ownership, and it depends on how widely that movement was used rather than on its quality.