what acids or aluminum brighteners have you tried? What one do you like best? I have only used aluma-brite but I am thinking of trying somthing different
I prefer my own recipe. It uses HF and sulfuric but works well. The HF is diluted won enough so it won't kill you, unless you should somehow submerge your body in a drum of it.
That's how the acid "cleans". It removes the oxide by etching it, which is why you can't use ordinary brighteners on polished aluminum. For those surfaces, you must use a non-etching acid based product containing oxalic and/or citric acid.
HF can also etch glass. It really works but can get you in trouble. More than one windshield has been purchased by fleet washers that turned untrained employees loose.
I'm not gonna open that can of worms again but anyone using HF needs to be aware of the possible health issues. It's so dilute in factory mixed solutions it's not much of an issue as long as you observe reasonable precautions. I don't have the knowledge to mix my own and would never consider it.