Step 4 · Apply New Plumber's Tape
Take your roll of plumber's tape (also known as Teflon tape or thread seal tape). Starting one or two threads back from the end of the shower arm, wrap the tape tightly around the threads in a clockwise direction. Overlap the tape by about half its width with each rotation. Make three to four complete wraps around the threads. Wrapping clockwise is critical because it prevents the tape from bunching up or unravelling when you screw the diverter on in the same direction. Smooth the tape down with your fingers to ensure it conforms to the threads.