Dave Hinz wrote:
...
2. HCl. ... It's _very_ nasty. ...

There's much worse. The home version of HCl is "muriatic" acid. The
fumes are very irritating if inhaled, but otherwise not so bad. I use
it all the time for derusting, get it on my hands, etc. I don't leave
it on my hands, but it's not particularly painful.

Biggest precaution is against its fumes - they *will* rust everything.
I only use it outside.

Bob