I used to work as a bench tech at a defense contractor (microwave equipment).
Every tech had a little bottle on their bench, with a special lid, that would have a small amount of liquid always in it (you'd pump it, to bring up more liquid). These bottles are still used, today.
This was for removing solder flux. Worked great.
At the end of each row of tech benches, was a red bucket, full of the same stuff. We'd use that to wash entire boards.
If you got the liquid on your skin, it made the skin turn white, and flake off.
Smelled like acetone had a one-night-stand with gasoline.
The liquid was trichlor[0] (not the pool kind).
Our management swore that it was perfectly safe, and that we could even drink it.
This was in the early 1980s.