PTFE is used on BSP fittings usually with a jointing compound. Examples
are radiator tails and outside taps, where the thread IS part of the
water seal.

You mean without, Shirley?

PTFE tape OR jointing compound (e.g. Boss White) poss. with hemp.

Nah, with. I smother the PTFE in Fernox LS-X. Works every time. Never once a
leak, even on parallel BSP.

I see PTFE as the hemp replacement and LS-X as the Boss White replacement.

Christian.