Water resistance of watches
People commonly wonder if it is indeed possible to take a bath/shower with a waterproof watch, to dive 50 meters deep if the case of a watch indicates that it is possible or if anybody has ever found it useful that a watch can go below 300 meters deep…
Before answering all these questions, it is essential to understand some basic notions.
WHAT IS A WATERPROOF WATCH ?
In the watchmaking industry, water resistance indicates the capacity of watch to resist water penetration. Mostly, this is stated in meters/feet or bar/atm.
Meters/feet correspond to the depth of immersion whereas bar/atm designate the mechanical constraint the watch is subjected when immersed - this also called overpressure. In the end, units may be different but they essentially measure the same thing, as overpressure is proportional to the depth of immersion. For instance, a watch with a “30 bar” inscription can go as deep as 300 m.
Nevertheless, it should be noted that the stated overpressure is a static one : it does not take into account water movements which can significantly increase the actual pressure.
There is a distinction between waterproof watches and diving watches.
Diving watches must resist to an underwater dive at 100 m or below, feature a time control system and meet light, shock-resistance, magnetic field resistance and strap robustness criteria. Norm ISO 6425 defines the various constraints on this topic. It is very strict as the precision and reliability of the data provided by the watch are of vital importance when immersed several meters underwater.
HOW CAN YOU CONTROL THE WATER RESISTANCE OF YOUR WATCH ?
Water resistance should not be considered as something permanent: seals ensure water resistance and may deteriorate over time. Water resistance may also be affected by knocks/shocks on components ensuring water resistance - crown, push button, glass…
Therefore, you should check the water resistance of your watch once a year or whenever it sustains a violent shock - even if it didn’t leave any visible mark. Water resistance must also be checked whenever your watch is opened - for revision or for a battery change, for instance.
WHAT CAN I DO WITH MY WATCH ?
The below table sums up some indications as to what you can do with your watch depending on the information provided on its case… Obviously, this is only valid for watches which water resistance is checked regularly.
HOW CAN YOU MAINTAIN WATER RESISTANCE ?
This may seem obvious but all “non water-resistant” watches must not be immersed in water or any other liquid. Steam should also be avoided.
Before immersing a watch in water, all components ensuring water resistance should be checked - they must all be where they belong - and these components should not be manipulated underwater.
Examples : the crown must not be pulled underwater to change date and time. Push buttons of the chronograph should not be pushed to start it. Indeed, water could seep through the crown or push button.
Watches should not be exposed to important temperature variations (hot shower, dive in cold water after long exposition to sunlight): this will accelerate the deterioration of seals.
For the same reason, you should always rinse your watch with freshwater after a swim in the sea or in the chlorinated water of swimming pools.
WHAT SHOULD I DO IF MY WATCH GOT WET ?
If condensation appears on the glass or on the back of your watch, that means water seeped into the case.
To prevent internal component from oxidizing, you need to act fast and visit a watchmaker who will open your watch, clean it, fix the water resistance and control it after reassembly.
If you cannot immediately visit a watchmaker, you can pull the crown of your watch and put it on a heat source to start evacuating humidity in the meantime. But be careful: even if the condensation disappears following this operation, you still must bring your watch to a specialist !