Also, Aluminum is known resist corrosion exceptionally, and won't deteriorate using a weak .1N solution of NaOH.
But, at higher concentrations NaOH can react with the Aluminum creating Aluminum Oxide...and etching wouldn't be nice.
So, as you mix the NaOH crystals in water be very aware of any stray crystals that don't make it in to your solution container. I've had quite a few of them stick on my arm, and not realize it until 30 minutes later when I have a little red mark on my arm that burns. Its nothing severe, but if your flashlight happened to be on the counter, and one of those little crystals got next to it, it could possibly eat a little dimple in the metal. Nothing too bad, but annoying at the least.