On Apr 2, 8:23*am, nestork wrote:
If it were me, I would:

A) Wrap those fine threads with teflon tape and then tighten the joint.
I realize they're not tapered threads, but the teflon tape will at least
stop the leak.

B) Next time use a WALTEC tail piece. *Waltec taile pieces are a single
piece unit that can't leak. *They use a big rubber washer at the bottom
of the sink which can be difficult to put on if you don't know to use
silicone caulk as a lubricant when assembling the tail piece onto the
sink. *If you slather up that Waltec tail piece with silicone caulk, you
can slide that rubber washer on no problem.

--
nestork

As nestork points out....

tail piece threads are not tapered threads
and as such, the joint is not meant for tape.

BUT tape can sometimes work in these situations.
I had a stubborn tail piece installation and used heavy silicone
vacuum grease to seal it.


An alternative that would work... RectorSeal #2 Soft Set
But I think #2 is no longer available,
replaced by #2 Plus Teflon (everything's gotta have teflon in it!)