On Sat, 05 Nov 2011 02:47:24 -0700, mike wrote:

oldyork90 wrote:
I'm looking for an acid based solder paste for electrical soldering.
I haven't purchased the stuff for years. Things have changed quite a
bit. We used to refer to it as an RMA type. There seem to be so many
kinds now,; no lead, no clean. It needs to reduce aggressively.

As others have said, there's a direct relationship between a flux's
ability to solder dirty stuff and it's ability to destroy electrical
equipment it's used on.

There's info at kester.com

I have some stuff called "tinner's fluid".
Best stuff I've ever seen for soldering tin and steel stuff together.
Only ingredient listed on the bottle is hydrochloric acid.
Not sure I'd wanna use it to fix my computer.
MOST tinners fluid is hydrochloric acid with as much zinc in it as it
will disolve. Ends up being Zinc Chloride. To make it you use dilute
hydrochloric axid and add zinc untill it stops producing hydrogen
bubbles. It is a much better flux than acid alone - but is NOT
suitable for electrical work as adequate cleanup is difficult if not
impossible.

Sal Ammoniac (Aluminum Chloride) is also used as a tinning flux. It is
mildly acidic and is a component of many soldering paste fluxes and
acid core solders. Also not recommended for electrical soldering, but
it is really handy for cleaning soldering tips (in block form)