Ferric Chloride

[R.G. Keen]

>...  Since aluminum is also more
>reactive than iron, it should work on that metal too, though I don't
>know if the rate of replacement is similar or not.

Oh, boy, does aluminum have a high rate of replacement!!!

I discovered this by making the mistake of trying to etch a circuit
board in an aluminum pan. Bad Mistake (the caps are not accidental).
This reaction goes fast enough to boil the FeCl - not to mention eating 
completely through the pan and spilling nasty etchant all over.

I was young, then...