: The elbow (?) joint on a copper pipe going up into my first
: floor shower is leaking around the joint. Hot water line.
: This is under floor (at basement ceiling, I can see it
: and get to it easily). New work - three months old. I
: need to seal it at least temporarily. I'm in a very rural
: area. I have some Dap silicone rubber sealant. Will this
: corrode the pipe? I also have some plumber's putty, some
: joint compound, and I'm sure I have some epoxy somewhere.
: Also some Liquid Nails/small projects. Will any of this
: work?

Try the epoxy for sealing pipes.
And then replace the fitting later if you can. It would be a sad thing for it to blow apart when you're not home. Terry