Plumbing? If I clean a copper pipe why does it still leak johndancer

Need some more information, like where is the pipe leaking from is it from a connection, is it a sweat pipe fitting, Thanks.

John

Do you mean when you clean pipe before soldering ?

1. Clean the end of pipe ( at least 1" area, all around ). For best results, use #00 steel wool
2. Apply Flux with brush
3. Clean inside of fitting with steel wool
4. Put fitting onto pipe
5. Apply heat from under, onto fitting, and apply solder from top
6. Once pipe is hot, it will melt the solder and solder will run evenly around the joint and creates droplet on the bottom. Capillary action will "suck" solder between pipe and fitting, making positive seal

Make sure there is absolutely NO water inside the pipe. Also, if it is a closed system, make sure you let air in. Otherwise heat will create pressure inside the pipe which will push fresh solder out of the joint.

Hope that helps

Back to you / Milo

Milo gave you outstanding instructions but to answer your question.
Plumbing? If I clean a copper pipe why does it still leak Could be lack of flux or not enough heat making a cold solder joint Try again. Tom

Or tightening the pipe cutter too much on the turns, so that the pipe isn't perfectly round (she said, speaking as a DIYer).

The problem may be that OP is not using enough flux, or none at all because he forgot it, or doesn't know he has to. I know of it because I use copper and flux for my stained glass. And yes, I am a 'do-it-yourselfer' as well !