>>>*If you can find a local machine shop that uses hot soaker tanks for spray booth washers, perhaps they will sell you a small amount of Sodium Metasilicate powder.

It is what we use. Simply mix a couple of tablespoons in about a pint of hot water. Wear gloves, the stuff is caustic to virgin hands.

It degreases aluminum very well without etching, brightens the metal up nicely. Severe stains take some brushing......*EB

*Beats the he** outa me!....*LOL**...