If you mean joining or repairing aluminum tubing in AC systems, there
is a much better product specifically designed for that: ESAB or
Allstate #31 rod with #31 flux. It wets and flows on aluminum like
silversolder does on brass or copper, and it makes much stronger
joints than the zinc-based "miracle rod". I learned about it and
saw it demonstrated at an ASHRAE show. It's what the pros use. It's
cheaper than the "miracle rod", works far better for me. NB: ya
gotta use the flux. The trick to this stuff is careful gradual
heating, because it kicks not far below the melting point of aluminum;
it really is brazing but it's not far below welding. With careful
gradual heating, it's a nobrainer. I've placed preform rings around
joints comprised of an Al tube thru a hole in Al sheetmetal, fluxed of
course and gently heated. The result was a very pretty fillet joint.
When I've tested such joints the parent metal failed, not the joint.

There may be something that has escaped me, but I've never thought the
results I got from the various zinc-based "miracle rods" with aluminum
were any better than epoxy, not much better than duct tape, and
certainly far inferior (in my hands at least) to materials as #31
and those offered by the Tinman. The only thing I think the
zinc-based stuff is any good for at all is in repairing potmetal;
I've had very good results with that.

Many others have reported good results with "miracle rod" and
aluminum, so maybe there's something I'm just not getting right. I
do get consistently good results with the materials that work for me.

On Sun, 07 Mar 2004 13:11:02 GMT, George wrote:

If it works on spark plug holes, that could be real nice. Have you
ever tried it on anything like a worn car AC condensor?