I have always assumed if you make a joint with pipe sealant / joint compound / pipe dope, you can test it immediately and there is no need to wait.

I used some joint compound yesterday when I applied a 3/4" brass cap to a 3/4" copper male adapter end. When I turned water back on it was dripping very slowly. I then tightened the cap some and it still dripped but even slower.

I was in a hurry so I turned main shutoff valve to off, opened one faucet to relieve some pressure in the line, and left. This afternoon I came back and turned water on, fully expected the cap to drip again, and it didn't.

What happened? Why was it dripping yesterday but not today? Did the pipe joint compound do a better job today then yesterday? I was using Oatey pipe joint compound.



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This is one instance that Teflon tape is best suited for. I always apply Teflon then a small amount of pipe joint compound that enhances the seal.

I don't use tape when joining metal to metal. I use tape only when joining plastic to plastic.

But regardless I don't understand why it was dripping yesterday but not today unless the joint compound behaves differently one day later. I don't understand what happened.

What ever you choose but for metal gas lines we used leak Tite green (they have changed the formulation and call it Leak Tite Blue now) for years and it worked perfectly as long as the trhreads were machined properly i.e. Good dies on your pipe machine.



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The threads are brass, so they probably "corroded" quickly and sealed the slight leak.