On 01/31/2011 10:50 AM, GROVER wrote:
A clerk at my local Ace Hardware told me to use Teflon tape on the
pipe threads but not the compression fittings. I'm trying to stop a
very slow seepage from the couplings and flex hose surrounding a
quarter turn shut off valve serving the cold water faucet to a
bathroom sink.

Is this advice correct?


Yes.

See the Wikipedia article on compression fittings to understand how they
work. Most important thing with those is to be clean and gentle with them.

Pipe threads are tapered according to the National Pipe Thread (NPT)
standard. See also the Wikipedia article about that. You need teflon
tape or a goopy sealant and a small pipe wrench to stop the leak there.