So, let me get this right,
acid bad
Alodine good.


Except when you use the acid to etch the aluminum before alodining it :-)
Shouldn't over-etch either (about 3 minutes in dilute acid solution).

2024 is protected by pure aluminun, but the coating is so thin and delicate,
that you are bound to put scratches in it. For 6061, at the very least,
prime on faying surfaces.