In general, the washers shouldn’t crack at all. They are designed to resist a torque that completely deforms the washer. If a washer does crack, it’s usually because it wasn’t stored properly. During our production process, moulded washers are conditioned in water. One of nylon’s characteristics is that it absorbs and maintains a certain amount of moisture to remain flexible. If washers are stored in low humidity or heat, or exposed to certain amounts of daylight or UV, this moisture evaporates, and the washers can become very brittle. This effect can usually be reversed by immersing the washer in water again for around 48 hours. The shelf life is normally very long if the storage requirements are respected; ideally at around room temperature, with normal humidity (50% to 60%).