The vast majority of watches nowadays need to be resealed after opening their case. This is always the case with watch brands such as Tag HEUER, Omega, Tissot and SEIKO. If this is not done the protection for the movement is lost as the seals are broken. Resealing watches is not just about water resistance, it is about protecting the watch movement against dust, dirt and pollution and prolonging the life of both the battery and the watch itself.
To achieve water resistance to manufacturer specification, watches need to be resealed at every entry point of the case such as crown (winder), glass, caseback, and pushers (for multifunction watches). If components are worn or defective, a watch cannot be resealed correctly without renewal of these parts. Testing of water resistance is carried out in numerous ways. There is the use of machinery such as a vacuum testing equipment, pressure tester, hot and cold condensation tests & the use of immersion wet testing apparatus.