What causes an inaccurate watch date?

　　"The watch calendar not advancing" is a common issue encountered during daily watch usage, and this problem has surely troubled many people. Below, I will explain the causes of inaccurate watch dates and how to resolve them.

　　Reasons for inaccurate watch dates

　　The calendar mechanism of a watch only advances once every 24 hours. However, the hour hand rotates twice in that period. If the calendar changes at 12 o'clock in the afternoon, the correction is simple: just rotate the hour hand clockwise by one full turn.

　　Most modern watches with a calendar (including day-date) function have a crown with 3 positions. When the crown is pushed all the way in, it is in the 'normal position', where rotating it winds the watch. When fully pulled out, the watch can be set forwards or backwards. Between the 'normal position' and the fully pulled-out position, there is an intermediate position used for quick-setting the calendar. By carefully placing the crown in this position, you can easily adjust the calendar of a Swiss watch by rotating the crown to set the date disc accurately.

　　How do you adjust the calendar on older Swiss watches without a quick-set function? You must adjust it by rotating the hands clockwise. A shortcut is to advance the date, then turn the hands anticlockwise back to the 7 o'clock position, and then rotate them clockwise again to the 12 o'clock position to advance the date, avoiding the need to continuously rotate the hands forward. The central crown is used for adjusting the calendar and time; pull it to the first position to adjust the calendar—if the date is one day ahead, rotate it until the date is correct (it is best to adjust the calendar in the morning). Pull to the second position to adjust the hands. The day and 24-hour displays on the three sub-dials are adjusted indirectly by moving the hands. The day and 24-hour settings generally do not need to be reset once configured, whereas the calendar requires manual adjustment every month, hence the direct adjustment method.

　　For watches with a screw-down crown, how do you adjust the calendar? Do not pull it forcefully. First, rotate the crown anticlockwise to unlock it. After setting the time, push the crown in and rotate it clockwise to lock it to prevent water ingress. If you need to adjust the calendar, set it to the day before the current date, then rotate the hour hand to advance the calendar. The date will change when the hour hand passes midnight at 12 o'clock; this prevents confusion between day and night and resolves issues where the calendar does not advance.

　　Watch Maintenance Knowledge

　　(1) When wearing a watch, perspiration on your hand can corrode the case. All-steel cases have better corrosion resistance due to their nickel-chromium alloy composition, whereas base-metal cases are copper and corrode easily when exposed to sweat for long periods. You should regularly wipe off sweat with a soft cloth or use a plastic watch protector pad to prevent sweat corrosion.

　　(2) Do not open the case back casually, to prevent dust from entering the movement and affecting the normal operation of the watch.

　　(3) Do not place the watch in a wardrobe containing mothballs, to prevent the watch oil from deteriorating.

　　(4) Do not place the watch on radios or televisions, to avoid magnetisation.

　　(5) For watches stored long-term without being worn, wind them regularly once a month to prevent the components from remaining stationary for extended periods, thereby ensuring the movement's running performance.