Tape, sealants & tools
Tape, sealants & tools
Thread tape, pipe dope, putty, primer and cement — which goes where.
Tape, sealants & tools
Using the wrong sealant is the most common reason a "finished" repair still weeps. Match the product to the joint.
PTFE thread tape (white)
General water threads. Three to four wraps clockwise, in the direction the fitting turns.
Yellow gas-rated tape
Gas appliance connections only — thicker and rated for fuel gas.
Pipe joint compound (dope)
Metal threads, alone or over tape. Stays pliable so joints come apart later.
Plumber's putty
Under sink strainers and pop-up flanges. Never on plastic that can crack or on threads.
PVC primer & cement
Purple primer then cement for PVC; CPVC needs CPVC cement. Hold the joint 30 seconds.
Silicone sealant
Around escutcheons, tub surrounds and fixture bases — a moisture seal, not a pressure seal.
Solvent cement is permanent. Dry-fit the whole run first, mark your alignment, then prime and glue — you get about five seconds to set the joint straight.