Randy G. wrote:If you use Teflon tape, use the white, 'light duty' stuff and not the heavy duty think stuff.
Be aware that there are many thicknesses of Teflon tape out there and they're all white. The "standard" US spec (which originated as military spec MIL-T-27730A) is 3.5 mil thick. But the tape you find in bargain bins and that comes with most inexpensive plumbing fixtures like $10 shower heads is only about 1 mil thick. This stuff is very fragile, stretches easily if pulled, and deforms so readily when wrapped around threads that if you don't position it right the first time you should disgard it and use a fresh length. It's OK to use if you're careful, but it takes a few more wraps than the better stuff (3 - 3.5 mil). You "save" pennies on the purchase price of cheap 1 mil tape, and it's false economy because you use more and have to reseal more joints that leak the first time.
There are many specialized Teflon tapes available in thicknesses as high as 30 and 60 mil - they sound great when you read the descriptions, but they're not for routine sealing of small pipe threads like ours.
Complete removal before resealing is essential, and it's not as easy as just pulling the old tape off. Thin filaments of Teflon are cut off by the threads when the joint is tightened, and they remain at the bottom of the groove. You have to use a small, sharp tool like a sewing needle or the tip of a very small knife to peel these strings of Teflon out of the threads on both sides.
The rule is to wrap in the direction of the thread you're wrapping, starting from the open end. So you wrap the threads on a pipe fitting clockwise looking at the end, because the actual thread runs clockwise toward the hub and the female mate will be threaded onto it in a clockwise direction. This pulls the trailing end of the Teflon tape in the same direction, so it stays flat and well apposed to the male thread while screwing the mating parts together. In case it's not obvious, you only wrap male threads with Teflon tape.