Having a water resistant watch around our wrist is something that we take for granted these days, especially since now even the Apple Watch can live up to this. However, it has always been a challenge to make watches water resistant. The general solution to this is (rubber) seals and screw down cases and crowns. Over the years these techniques have been significantly improved, allowing watches to become more and more water resistant, but there are still a few things to keep in mind!
Many people think that high pressure is a problem, and although it eventually will when you take a watch too deep under water, the opposite can be equally challenging. Most diving watches are constructed in such a way that the water pressure actually helps to seal the watch better. Increased pressure on for example the crystal will push it tighter against the rubber seals, making it harder for water to enter the case. This is why taking a shower with your watch on, apart from the soap, can lead to moisture entering the case, especially when
Pressure is also not always depth. When you keep your watch on while swimming, it might only be submerged a few inches, but while you move your arms, the pressure you generate is much higher than you would think.
It is not only keeping moisture out
Sometimes you see watches with a relatively high water resistance yet fitted with straps of exotic leather that are not waterproof, or the watch itself is crafted from gold and more a dress watch than a diving watch. Why would brands go through the trouble of making these watches water resistant? Because it is not only moisture that they keep out but also dust.
Dust can be almost equally destructive when it enters a watch movement, as it will get caught in the oils of the watch, making it harder to run properly and increase wear. Making a watch dust proof and water proof requires the same approach, with the difference that we can actually measure water resistance.
This also makes it so important to test the water resistance of your watch on a yearly basis. Any watchmaker, brand boutique or retailer can easily do this without even opening your watch, or even submerging it into the water. By putting it in sealed pressure dome they can measure if air is actually entering the case, and when it does, so will water, and a service is in order.
Common sense rules
When it comes to water and watches common sense can prevent a lot of costly repairs. Unless recently serviced and given a water resistance report by the brand or watchmaker vintage watches, even vintage diving watches, should not be mixed with water. Some vintage watches might have been water resistant at some point in their life, but normal wear and tear of decades of use can influence this, and for not all watches the correct seals are still available. Also, your golden perpetual calendar might have been rated to a water resistance of 165 feet we would not take the chance.
Before you enter the water, check if the crown (and other pushers) are correctly sealed. When you come out of the water, always rinse your watch with tap water. Salt and other chemicals in the water can have a negative effect on the seals of the watch, and rinsing your watch can prevent damage. The same goes for soap and sunscreen, which should ideally never come in contact with your watch.
The water resistance of watches has come a long way in the last decades, but it is good to know that even when your watch has a higher depth rating then a nuclear submarine, it will require good care and maitenance to keep it that way.