Plumber's tape is recommended for use with most threaded connections that don't have a built-in rubber seal. It also helps lubricate the connection, making the threading a bit smoother, and it helps to prevent pipes from sticking when you want to disassemble the joint. Plumber's tape is very easy to use, but there's a right way and a wrong way to apply it.
What Is Plumber's Tape?
Plumber's tape, often called Teflon tape, (polytetrafluoroethylene, or PTFE) helps you get a watertight seal on threaded pipe joints.
How to Use Plumber's Tape
The trick to getting plumber's tape right is to wrap it around the pipe in the proper direction. When the pipe is turned into the fitting, the friction of the mating threads should work to tighten the tape around the pipe, rather than work against it and unravel or ball up the tape. Therefore, you wrap the tape around the pipe in the same clockwise direction of how the pipe will turn into the fitting. This way, it won't unravel while making up the joint.
Clean the Pipe
Clean the male threads at the end of the pipe with a clean rag.
Line Up the Pipe and Tape
Place the end of the plumber's tape on the second thread from the end of the pipe and hold it in place with a finger or thumb. The tape should lie flat (not bunched up) over the threads and extend perpendicularly to the length of the pipe.
Wrap the Tape
Begin wrapping the tape around the pipe in the same direction as the direction the pipe will be turned.
Keep the Tape Tight
Maintain tension on the tape so it wraps snugly around the pipe. Work away from the end of the pipe, overlapping the tape as you go.
Wrap 4 to 6 Times
Complete four to six wraps around the pipe, finishing near the end of the threads (opposite the end of the pipe).
Break the Tape
Break the tape from the roll by gripping it between thumb and forefinger and pulling sharply; it breaks easily. Smooth the loose end down over the threads. The pipe is now ready to go into the fitting.
If you're familiar with using pipe-joint compound (pipe dope), you can substitute with plumber's tape in the same applications. It can be used on all standard metal pipe materials as well as rigid plastic pipe. Common places to use plumber's tape include:
Ask for "Teflon tape" in any hardware or home store and you'll get what you need, but there's no product that carries this name. DuPont, the maker of Teflon, never manufactured plumber's tape. In the late 1960s, tape manufacturers used DuPont's Teflon in the form of a fine powder, applying the powder to their own plumber's tape. These manufacturers were allowed to use the Teflon name in association with their products but only if they used the real Teflon on their tape. Eventually, tapes were more commonly made with knockoff versions of the same material, and these cannot use the Teflon brand, which is now owned by Chemours.
Today, the most standard industry term for plumber's tape is thread seal tape or thread-sealing tape. To further confuse matters, the term plumber's tape is often used to describe metal or plastic strapping with holes in it, designed to support pipe.