Plumber’s tape is essential for threaded connections – such as a Ball Valve or Thermometer – in order to prevent thread binding and enhance the water-tight seal. Wrap the tape around the male threads until the threads are completely covered. It is recommended to have at least two layers of the tape wrapped around the threads. Then cut the tape and smooth the loose end against the threads in the direction of the rest of the wrap. Now you are all set to screw the male threads into the female receptacle.
TIP: When wrapping the threads, the roll should be oriented so that it is dispensing the tape from the underside of the roll. It is more difficult to work with when the tape is cascading over the top of the roll while you are wrapping.