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Knowledge of Watch Maintenance

Water Resistance
Waterproofing of a watch mainly relies on the rubber circles of the crystal, watch cover and watch crown. Screw-in crown is adopted to guarantee conformity to waterproof standards. Watch waterproofing is classified as follows:
  • Non-waterproof (no label on the watch bottom)
  • Sweat-Resistant
  • Water resistant, 30m water resistant (30M, 3ATM, 3BAR), 50m water resistant (50M, 5ATM, 5BAR).
  • Diver watches are classified as 100m water resistant, 200m water resistant, 300m water resistant, etc.
There are specific national and international standards on the water resistance of watches: all watches that are expressly classified as waterproof shall stand a minimum water pressure of 2 atmospheric pressures, i.e. in a depth of 20m. 30m water resistant indicates a withstanding pressure of 3 atmospheric pressures and so forth. The premises of such standards are based on tests results carried out in lab conditions, i.e. the temperature is kept within 20℃ and 25 ℃ and both the watch and the water are in a static state. The watch is up to standard if no water ingression is identified in such conditions.


30m waterproof watch indicates that the watch can withstand a pressure of 3kg per square centimetre, or equivalent to 30m water pressure or three atmospheric pressures in a static state. The design primarily prevents damages caused to the watch movement by dust and moisture but not applicable for immersions in water and swimming. Waterproof watches of 100m or higher depth are applicable for diving and other aquatic sports. No waterproof watch can be used in a hot water bath, sauna bath or under substantial temperature variations because the waterproof rubber circles will expand or shrink subject to temperature fluctuations and hence gaps and accelerated aging will occur, diminishing water resistance. Any water ingression arising from such improper operation is not within the scope of warranty. Always keep the crown in place and fasten any screw-in crown. Do not adjust the crown in water. The rubber circles and the crown must be regularly replaced according to operating conditions.
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