Recently installed a towel rail, and had a lot of problems getting a seal on the valve tail where it screws into the rail. Initially I was using normal PTFE tape which failed even with 20 turns of it. Then tried gas tape which also weeped. Thought I had fixed the problem using LSX on its own, but after 2 weeks the joint is weeping again.
Any recommendations for getting a good seal on what seems to be a very sloppy screw thread?