On Oct 23, 10:06 am, professorpaul wrote:
As to "good" joints (lot of experience soldering all sorts of stuff
here), I can tell a good joint generally just by inspection. This
applies to electronics as well as pipe, etc.

You should see a meniscus of solder evenly flowing between the two
items. There should be no "bare" spots, or clear inclusions of crud,
excess solder, blogs, etc. Look at the joint with a magnifying glass,
if possible. If the joint is in a hard to get at location, then
observing the back side can often be done with a good flashlight and
inspection mirror.

O-boy, I may redo a couple of my other fittings after doing this. At
least the first two couplings I did, which are now closed off already,
looked really good. They didn't even leak the first time, but I redid
them anyway because I wasn't happy with the way they looked, and I
didn't want to open the wall again after I closed that part.

I really like rosin core solder, even for plumbing. The new lead free
solders work at a slightly higher temperature, and in my experience
are harder to get good joints with, especially if you have grown up on
lead bearing solders. I am reluctant to use acid core solder, as the
residue is hydroscopic, and corrosive, and will come back to haunt you
later.

I think I started with an acid core solder, and those first two
couplings were that kind (they are already closed off, so I sure hope
I don't have problems with them). I got the one marked "premium" the
2nd time (I used a whole pound of solder doing the first two
couplings, until I learned how it should really be done, then only
needed the last few inches to do the job right). This "premium" says
something like "solid wire", don't have it in front of me, but I do
recall it didn't say "acid core" like the 1st one I had.

Also, I find it useful to "pre fabricate" as much stuff on the bench,
then finish up with maybe two joints to be soldered in the final work.

Yes, I started doing this after a while, and it is a great idea.
Another plus is that I don't have as many burn marks on the sheetrock
and studs =] Just kiddin, I'm being safe.

Also, in working with OLD plumbing, you have to deal with corrosion.
Sometimes I've used compression fittings instead of soldering. Of
course, use TWO wrenches to tighten them up so as not to twist the
pipe.

I was thinking about trying something else (I read about "Sharkbites"
as well), but I think if I get to that point, I'll just call a
professional instead. I'm putting $500 worth of tile over this job,
and don't want to tear it out.