Every year, it is good to go over what you can and cannot do in summer with your watch, based on its water resistance rating. First of all, don't rely too much on your memory, but go and check the value on the watch back: from the simple inscription 'water resistant' to the indication in metres (30, 50, 100, etc.) or in atmospheres (3, 5, 10, etc.). Each figure corresponds to the watch's ability to resist water infiltration under static conditions, i.e. stopped under water at the corresponding, uniform pressure reproduced in the laboratory.
However, when the watch is in motion, i.e. under all normal conditions of use, the pressure of the liquid to which it is subjected may be considerably higher than that generated by the simple depth of immersion. It must be considered, in fact, that in the case of exposure to jets of water, such as in the shower or at the sink tap, the point pressure on the various surfaces of the case may vary and will not be as uniform as in static immersion. It could happen, therefore, that in some places the pressure of the water is higher than that withstood by the watch in the laboratory.
Moreover, remember that the watch case is composed of several elements assembled together, with the interposition of gaskets in materials ranging from metal to rubber. As the temperature varies, all the materials expand with different coefficients, especially in the case of sudden temperature changes (the classic plunge into freezing water after being in the sun) and may no longer withstand the guaranteed water-resistance figure, causing water to seep into the case.
Although the manufacturer tests the resistance of the watch in all the most stressful situations, remember that the tests are carried out on new watches. Therefore, a periodic inspection of the gaskets and the sealing of the case, crown and any buttons is essential, especially before a seaside holiday.
Dody Giussani
