Years ago, I spent a few months working for a plumber who spat out pearls of plumbing wisdom like a Pez dispenser. Here’s one of his best maxims: “Always dope everything.”
Translation: Use dope (pipe thread sealant) on plastic, rubber or metal, on washers, rings or gaskets, and especially, on anything that has threads.
Even if the threads don’t actually form the seal (as on washing machine hoses), they screw together easier and come apart easier later. And things that don’t really require sealant (like compression fittings) slip together smoothly and seal tighter with a little dope.
My favorite thread sealants contain Teflon. Be sure to choose a non-hardening product, and READ THE LABEL. Some sealants can wreck plastic or rubber parts. My thread sealant of choice is Rectorseal’s T Plus 2.
– Gary Wentz, Senior Editor