Mechanical watches and water resistance – How does it work?

Water is a threat to any watch mechanism. In contact with the calibre, water could damage and eventually break some parts (due to corrosion/oxidation and the bad mix between oil and water). Are watches water-resistant? And how should you wear them? We’ll have a look at that in this article.

Enjoying a sunny evening by the Leman lake in Lausanne with the classic Rolex Submariner 14060M

A photo posted by Toolwatch ⌚️ (@toolwatchapp) on

Water-resistant watches are classified by water depth (3 bars, 5 bars…).
First of all you should be aware that those criteria are established for brand new watches (not even worn once) and tested in optimum condition (laboratory). Watches get less water-resistant over time and need to be tested on a regular basis, every one to two years especially in order to renew the gaskets.

To have a better understanding of the water resistance concept, you will find below:

  • A focus on how a watch gets “water resistant”
  • An explanation of all different water resistance categories and what they mean for your watch

Components required for a water-resistant watch:

Three main components make a watch “water resistant”:
-> The caseback
-> The crown
-> The gaskets

Those three parts are the most sensitive to water. Below are the different ways they are built with the pros and cons towards water agression.

  • The caseback:
    It is either sealed, attached with screws or screw-in to the case. The most efficient technic against water infiltration is the screw-in one. As for example, all Rolex Oyster Perpetual cases are made like this.
  • The crown:
    The crown is either mobile (you can wind the watch in position 0), or screwed to the case (you need to unscrew it to set the time). The first system is usually less resistant to water as it all depends on the gasket set between the case and the crown.
    The second system is way more efficient as the crown is screwed to the case.
    However, for both type of crown the gaskets need to be check often as it is constantly submitted to different environment changes in the day-to-day life (air and water pressure, atmosphere degrees’ variation, skin temperature variation, etc…)
  • The gaskets:
    As mentioned above, the gaskets are the last shields to water. They are made of rubber, nylon or Teflon and they are the joints between all case’s components (crown, pushers, caseback and sapphire crystals). Gaskets dry and erode during the watch life, diminishing their role against water. Therefore all watches should be tested by professional watchmakers on a regularly basis.
    If your watch starts getting some important precision variations, it might come from a less efficient water resistance. We recommend checking your watch accuracy here 😉

Water resistance categories:

Water resistance is controlled by two ISO certifications, with two different tests and controls. The 2281 concerns water resistance for short period of time in day-to-day life. On the other side, the 6425 is made for diver’s watches, which means you can  use your watch as a professional diving instrument.

Finally, a classification in bars exists to better understand what’s written on your watch caseback. You’ll find it below. Pay attention and be aware that a water resistance of 3 bars does not mean you can actually take your watch with you for a swim, it only means your watch is resistant to dust !

Below 3 bars This is not water resistant and you should not have contact with water
Between 3 bars and 5 bars Contact with water not recommended but washing hands and rain will not damage the watch
Between 5 bars and 10 bars Swimming is ok inside pools (low pressure and clean water)
Between 10 bars and 20 bars Swimming, snorkelling and showering is accepted
Between 20 bars and 50 bars Fully resistant to water and impacts (e.i. water sports)
Above 50 bars Deep diving accepted

One last thing: Do you know which brand created the first ever water resistant wristwatch?
-> Rolex in 1926 with the Oyster model
The bezel and the caseback were screwed to the case. One year later, Rolex sponsored Mercedes Gleitze in her swim across the English channel. The watch was still working properly after her 10-hour swim.

Résultat de recherche d'images pour "rolex oyster 1926"

See you soon for a next article to help you taking care of your favorite timepiece !

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