B.B. wrote:
Can I get a quick explanation of rosin core vs. acid core vs.
whatever else I may run into? Is there one solder that's basically a
general-purpose type, rather than having to keep several around? AFAIK,
acid core is for dealing with stuff that has varnish or oxide over it.
The acid just takes off the varnish for you. Whereas rosin core is for
other stuff. I suppose freshly stripped wires fall under "other."


B.B. --I am not a goat! thegoat4 at airmail dot net

Rosin-core is just that, solder with a rosin core. There's also an
activated rosin core that's more expensive but worth it for joints that
are oxidized and otherwise hard to clean. Rosin isn't as an aggressive
as other fluxes at removing oxides, joints should be bright metal,
scrape or sand or do whatever you have to to get bright metal, then
don't handle with greasy fingers afterwards. Can be used for
mechanical joints, too, just not very aggressive with joining up steel
parts or galvanized

"Acid" core stuff usually has zinc chloride("killed" acid used to be
the old plumbers' term) as the active ingredient, it's supposed to be
used for mechanical joints, gutters, architectural sheetmetal, etc.
It's not used on electrical joints at all, period. The residue will
sit there and slowly convert your wires into copper chloride, even with
water flushing you can't be sure that the flux didn't get into the
insulation. Works great for its intended use, though. This stuff will
rust any steel within breathing distance, too.

There's also paste fluxes with zinc chloride, ammonium chloride and/or
rosin in them, these are intended for much larger-scale projects where
they'd use a 5 lb soldering copper and a blowtorch in the old days,
like roofing and large gutters. Don't use on electrical joints,
either.

In some areas, all you can get is the tin-based, lead-free solder, this
probably has it's own peculiarities. As long as the flux isn't choride
based, it's probably OK for electrical joints. I haven't had to use it
yet on anything but plumbing, but the time will probably come.

Stan