1" threaded copper union leaking
I'm wondering what the proper way is to install a "ELKHART 33584 UNION C TO C 1" COPPER" (or similar) fitting to keep it from leaking
I had to replace the house water shut-off valve, and I had lots of trouble soldering due to the bending stresses of the existing pipes, so I cut the line downsteam and used a 1" copper threaded union to allow me to solder the joints in free air, then screw the last joint together.
The union uses a simple rounded seat and mating rounded head on the two pieces, and when I first assembled the joint and turned the water on, the joint leaked profusely through the threads. I took it apart used some teflon tape wrapped partly around the thread, and partly lapping into the seat of the joint.
After turning on the water, I got only a little slow drip, and with time it seems to be stopping.
Is there some other trick I should have used?