How do I Care for a Water Resistant Watch

It is not recommended to wear even a highly rated water resistant watch in a hot shower, sauna or bath the degree of water resistance e.g 100m or 300m makes little difference to the risk. The basic problem is that the extreme heat causes the metal parts to expand at a different rate to the rubber gaskets, the result is that it can create small openings which allow water to penetrate the watch, the result is most commonly misting of the crystal but over time it can result in increasing amounts of water ingression which seriously damages the movement. The other issue that aggravates matters further is shower gel, soap, shampoo and bath foam because these are alkaline and can rot the seals. 

Another risk factor with all watches is the effect of sudden temperature changes, these are especially harsh if – for example – you lie in the sun and then dive into cold water etc which causes thermal shock.