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ATM Rating


You will see watches rated by ATM or atmospheres, 1 ATM = 33 feet below the surface of the ocean. This refers to the structural style of the watch case, for example heavy duty as opposed to light duty or home use only. Most watches are rated from 1 to 10 ATM so use your watch accordingly.

The problem is that this rating is given when the watch is new and the gaskets are soft and fresh. As time passes and the watch is worn the gaskets become hard and will let moisture pass through.

You can't stop Mother Nature!

When you wear your watch it warms to about 93 degrees, the air inside the watch expands and some leaks out. Then when the watch is removed, it cools and any air that leaked out is pulled in along with dirt and moisture. This happens everyday you wear the watch.

The most common place that a watch will leak is around the setting crown. This o-ring gets the most wear. As you move your wrist the crown is moved slightly and it is exposed to sweat and moisture. Once it gets hard it is no longer pushing on the surface of the case tube.

The gasket for the case back is well protected but, if the back of your watch unscrews it will stretch and not seat properly after a battery change. This may also happen on a snap back case because the rubber is compressed for a very long period of time then released.

Push buttons are a whole set of problems of their own, and are as bad if not worse than the setting crown.

We recommend changing the crown and gaskets every 3 to 5 years depending on how you treat your watch.

The most simple way to protect your watch is:


Unless you are actually SCUBA diving, and you have a professional dive watch that is tested and serviced on a regular basis. There is no good reason to intentionally get your watch wet. None. OK, maybe jumping in a lake to save a drowning child I can see, but nothing else !


See also: TMP Company Supplies:
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