|
Easy off, sodium hydroxide, is a real stiff base with a pH of 14. All it will do is reform the natural oxide coating. My guess would be that any stains (dark areas) are left over organics (oils) in the metal pores. Hydrogen peroxide should do a number on any stains (react with the hydrocarbons) but it won't hurt the aluminum. Hydrogen peroxide is stored for decades in aluminum vessels in satilites for the adjustment jets. I'd get the stuff for bleaching hair, 10%, iirc. Wear gloves and eye protection and use a stiff nylon brush.
|