Watertight watches can be immersed in water up to a certain depth. Such watches have a boundary depth of immersion, which is safe for them. Evaluation of water resistance is usually based on the results of laboratory tests.
However, over time aging of seals and wear of moving parts reduce water-resistant characteristics specified by manufacturers. The worst thing that can happen to a watch is when its moving parts are used directly in water (for example, pressing chronograph buttons in water, rotation of the crown in water). To maintain a watch operating reliably and within manufacturer’s characteristics, experts recommend checking a timepiece in special workshops at least once a year.
Any competent watchmaker has necessary equipment to test water resistance. The crown design serves one of water resistance determinants. The axis of the crown is the most vulnerable part in terms of water penetration.
In some designs, axle crown goes through special seals that prevent water penetration. There are designs with multi-layer seals (alternating layers with different physical characteristics), so-called orchestras. However, given the fact the axis of the crown must rotate and move, all seals are eventually worn out.
One should distinguish between water-resistant and waterproof watches. Most water-resistant watches can stand small amount of water within a short period of time. Washing hands or being in the rain will not harm water-resistant watches. However, taking a shower (especially with gel) or long submersion will cause penetration of moisture into a case and damage mechanism.
Swimming and diving require special waterproof watches. These watches usually feature threaded connection of the crown and back cover with case. To avoid water penetration and damage of mechanism, the crown should be fixed on a thread. Do not screw up the crown too tight, otherwise you can damage thread and gasket. Tightness is complete, when screwing is done with a slight effort.
Do not switch on a chronograph (except for diving watches), when its case is in the water. Water can penetrate into a case through holes under the buttons.
There also exist more professional diver’s mechanical watches. They are able to withstand pressure at depths up to 1500, 2000 and even 6000 meters. These watches are usually equipped with a helium valve. It equalizes internal and external pressure inside the case during ascent.
Over 2-3 years, your watch can lose integrity because of gasket aging. Therefore, check tightness at authorized service centers once in three years.
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