What to try next when pipe joints leak with both thread sealant and with teflon tape?
Never put pipe dope on the threads of the female fitting. It will allow pipe dope which is not water soluble to clog aerators and put contaminants into the water. If the threads on both male and female fittings are threaded correctly and with sharp dies the threads should hand fit up to 2-1/2 threads.Pipe dope and tape can be applied in excess. 4 wraps of tape on the male threads with a quality Teflon tape is sufficient, wrapped over itself clockwise looking from the narrow end of the threads. Or paste pipe dope should be applied to the first 4-5 threads of the male threads and not gooped on. No pipe dope whether tape or paste should get inside of pipe. Not a good thing. Tighten the joint until it is snug, not until it can not be tightened any further. It is a feel or touch thing you will aquire with practice. Turn on pressure whether liquid or gas and test for leaks. If there is a leak and you didn't tighten the joint so tight you hurt yourself you can tighten it little more to stop the leak. If you tightened it so tight there is no more tightening you must untighten the joint completely and start over. PITA. Have been doing this for 48 years and has never failed if threads are good quality threads. Problem today 50% of threads are crap. Remember the fit up. If to loose or to tight get rid of bad fitting.