A federally approved term to indicate the amount of pressure a watch can withstand under water without leaking or losing accuracy.
Water Tightness is achieved by installing seals between major parts of the watch case and a specially designed setting crown which, together, prevent moisture from entering the case.
Not a permanent condition
In order to maintain the integrity of this water resistant system, periodic maintenance is required.
Gaskets between the case back, setting crown, & crystal deteriorate over time under normal use as they are subject to many aggression's; dust, cosmetics, perspiration, temperature changes, etc. leaving your watch vulnerable to moisture damage.
Therefore these parts must be inspected periodically and replaced as necessary. In addition, water-resistant watches must be tested to ensure a proper seal has been re-established.
The water resistance of watches is measured by laboratory pressure test that are comparable
to a swimmer or diver “at rest” at that level of pressure.
The different levels of water resistance as expressed are only theoretical.
Consideration must be given to the additional pressures caused during many water based activities which involve movement & other environmental changes that may defeat the water protection features of water resistant watches.
These exceptions include the following:
- *Sudden, rapid, & repeated water pressure changes experienced by the wrist of a surface swimmer.
- The force of plunging your arm into the water while swimming can for a fraction of a second greatly exceed the static pressures the watch was designed for.
- *High water temperatures as experienced in a hot tub can damage the seals.
- Sudden temperature change from 100 degree F of a hot tub to 70 degree F of a pool causes contraction of the case and seals at different rates which may allow water to leak in.
Look for resistance levels printed on the dial or case back of the watch. An absence of any indication indicates extra caution is necessary to avoid contact with moisture. This is common with expensive "dress" watches.
Micro processor based measurement system.
Leakage rate is always referred back to the ISO 2281 Standard.
An unquestionable result is obtained.