OK.. to pose myself a challenge, but do something small at the same time, im polishing the aluminum alloy tip of a AH64-d helicopter tail rotor blade..
the tip had flat black blade carc, green anti corrosion inhibitor, and then it was POWDERCOATED (that thats from the factory bottom layer)
and it had some splotches of "pink stuff" (as we called it) 9309* aviation adhesive.. (bondo eat your heart out.. jb weld go away..good stuff)
to start i sanded with 100 grit.... (i cheated and used a palm sander)