I'm reminded of the time a student in an automotive class
put his engine block in the caustic solution over the
weekend. It works great on a cast iron block. Removes all
the crud, paint, etc.

However, on Monday, when he opened the tank to remove his
block, all he found was a few bits and pieces plus the
cylinder liners.

Caustic solutions and aluminum are NOT a good mix. Even an
aluminum engine block can be "eaten away". Think what it
will do to a thin aluminum skin...

John

I think the worst thing many of us has seen is someone buffing away
the alodyne on an older airplane to shine it up. Once the alodyne is
gone, the shine doesn't last and the skin re-oxidizes deeper. It
corrodes the airplane away in short order.

BWB