Water resistance testing for watches

There is currently a misconception when buying watches, as consumers often focus primarily on price, timekeeping accuracy, appearance style and exterior quality. As long as these aspects meet their preferences, they assume they have bought a satisfactory watch. This mindset actually overlooks the single biggest factor affecting a watch's quality and future lifespan: water resistance. Looking at current media reports, poor water resistance is one of the most common complaints consumers have about watch quality. Leaving aside market stalls selling items for tens of yuan, even domestic brand watches worth hundreds, imported watches worth thousands, and luxury high-end watches worth tens of thousands occasionally suffer from water ingress that compromises quality or even ruins the movement, causing financial losses to the consumer and reputational damage to the product itself. There are many factors that cause a watch to lack water resistance, but the most crucial point is whether the watch achieved the proper water-resistance performance indicators during manufacturing.

So, how do modern watch companies determine whether a watch has water-resistance performance during production? According to the current international water-resistant watch standards iso2281-1990 and China's light industry water-resistant watch standards qb/t1897-93 (which identically adopt iso2281-1990), manufacturing enterprises must test watches for resistance to water temperature changes, mechanical pressure, air pressure, or water pressure (air pressure and water pressure tests are interchangeable). Once the performance indicators meet the standard requirements, the watch can be considered water-resistant and is designated as a water-resistant watch. Conversely, it cannot be called a water-resistant watch. The air pressure test places the watch inside the container of an air-pressure water-resistance tester and subjects it to an air overpressure of 2bar (approximately equal to 2 atmospheres) at normal pressure. If the air leakage rate of the case is no greater than 50 micrograms per minute, this metric is considered compliant. Meanwhile, the water pressure test places the watch inside the water container of a hydraulic water-resistance tester (with the watch completely immersed in water), applies 2bar of pressure under normal conditions for 10 minutes, and then uses a condensation test to check whether condensation appears on the watch glass to determine if the water pressure resistance meets the standard. Purely judging by the metrics, water-resistant watches produced in strict accordance with international standards have no issues with their water resistance. Because when people wear watches for everyday activities (including leisure swimming), the water pressure endured by the watch is far less than 0.5bar, leaving a considerable safety margin for water-resistant watches. However, experts later discovered that some water-resistant watches still experienced water ingress during use. On the one hand, this is due to how the watch is used. For instance, if a watch has been used for a long time and exceeded its water-resistance warranty period, if the wearer engages in diving or strenuous water sports, if the watch suffers external shocks and impacts, or if disassembly during servicing or battery replacement leads to a decline in water-resistance performance. On the other hand, the air pressure test is only an approximate substitute for the water pressure test rather than an entirely identical test, given that the test environments use fundamentally different mediums; the air leakage rate in an air pressure test does not equal the water leakage rate in a water pressure test. A water-resistant watch that has only undergone the air pressure test will generally have no issues if placed in water for a short time, but prolonged immersion cannot guarantee that water will not seep in. In view of various factors, member states of the ISO International Organization for Standardization (of which China is an important member) have unanimously agreed to revise the current international water-resistant watch standards to add extra safety margins for water-resistant watches.

Currently, member states are negotiating the revisions to the international standards, with the majority of member states proposing the addition of the following 3 safeguards:
　　1, changing the water pressure resistance test from an optional test to a mandatory test.
　　2, increasing the pressure during the water pressure resistance test from 2bar to 3bar.
　　3, extending the immersion test duration (with the watch completely placed in water at a depth of 10±2 centimetres) from 1 hours to 4 hours.

If the aforementioned safeguards are passed and become the international standard, water-resistant watches produced under the new standard will enjoy enhanced water-resistance performance, and their water-resistance warranty period will also be extended. Therefore, consumers must pay closer attention to water resistance when selecting and purchasing a watch. Water resistance protects the value of your watch, whereas a lack of it could quickly sink your investment.