The term "waterproof" comes up in the subject of watches from time to time.Some people market "waterproof watches" being able to never get wet. This is not the case however, as no watch is water proof. There is a big difference between water resistant, which is the actual term and water proof. Think of it this way; would you rather a shirt that is fire resistant, or fire proof? Proof in this sense means that under any conditions, water cannot get in. Resistant means that it will resist water until certain conditions are met.
The big conditional factor in water resistance is pressure. As the depth of water increases, the pressure the water has increases. This is because more water is affecting the object.In a watch, gaskets are used to keep water out. these gaskets are rubber or plastic in nature and are usually lubricated to add to the water resistance. Once a certain water pressure is reached, the water will force itself pass the gaskets. There are a few vulnerable gaskets, The crystal, the crown and the back.
For Crystals, UV adhesive is usually used to fix watch crystals to the watch. Hypo cement may also be used to help in the water proofing.For backs, A gasket is almost always added. Some watches have screw on backs which also help water resistance. The crown will sometime have a small gasket to prevent dust and water from getting in, but not always. Watches with screw down crowns are more water resistant than those without.
If a watch just says "water resistant" it usually means that you can do everyday tasks such as washing dishes or sweating a little. Most watches say "water resistant till x feet", meaning that the watch has been tested to be water resistant until the listed depth.
The classification for watch water resistance is listed "ISO 6425 ".The minimum to pass this listing will appear as under "diver's 100m"
Currently, the most water resistant mechanical watch is the CX Swiss military 20,000 feet diving watch. As the name suggests, it can remain water resistant for a total of 20,000 feet under the water (also known as 3.79 miles)
