INFORMATION ON WATER RESISTANCE
Water resistance is measured in bars (a bar is a unit of pressure, 1 bar being equivalent to 1 atmosphere), and watches are tested at these pressures in a static laboratory test for a short period of time. Exceptional pressure, as when diving, or prolonged and active use in water may exceed those limits. If the watch is to be used for diving or impact water sports it will need to be able to tolerate that extra pounding. Thus in all practicality the limits stated on the watch should always exceed those of its actual use.
Translation of water resistance varies and the best guide is the supplier or maker of the watch as it will almost certainly be part of the guarantee. Manufacturers often measure water resistance to a number of feet, meters or atmospheres (ATM). Normally, terms of depth imply that a watch will remain resistant at this (Atmospheric pressure) depth in still conditions. As a general rule, the minimum could be described as follows:
It is wise to remember that when mountain climbing, parachuting, sky diving, hang gliding, or skiing, you may also require a watch that is ATM damage-protected, as pressures change both above and below sea level. Always ensure that any screw down crowns or pushers are properly fastened tight as this can compromise the water resistance of your watch and invalidate any warranty, if water enters because they where not screwed down.
Re-sealing your watch
Most watches produced today are water resistant to at least 3ATM. For a watch to still be water resistant the seals and gaskets should be replaced periodically. This is usually best done when replacing the battery or when ever any work is carried out on the watch. The rubber gaskets that seal the case back, crystal, crown or pushers will inevitably deteriorate with time. Thus water resistance is not a permanent condition. When removing case backs, the case back gaskets often break or stretch and should always be replaced to guarantee water resistance. The only safe way to know if a watch is water resistant is to test it in specially designed vacume and pressure test equipment.
When resealing a watch the movement is removed and all case components stripped down as far as possible. This includes the removal of crowns, pushers and in some cases the besel and the crystal. The individual components are then first cleaned in an ultrasonic tank and then steam cleaned to remove any dirt or debri which may other wise damage the new gaskets. The case is then re-built using the new gaskets, crowns or crystals where necessary. A special silicone grease is also applied to the gaskets to stop them nipping and breaking when the crown is turned or the case back fastened. The watch is then tested to ensure it meets the specified depth indicated on either the dial or case back.
The price of a re-seal usually depends on both the type of watch and on the make and brand, as some watches require a new crown to be fitted as the seals inside some crowns cannot be replaced.
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