I have a customer that i recently did commercial window screens for, installed with a tricket he loved my work and he seen on my card that i do hard water removal. He asked for a quote on removing hard water off the Aluminum frame work on the entry of the building. Got the job done and here is a before and after picture.
As you can see in the before picture i tested a few areas and that stood for a week. I did not dilute the one restore. Other aluminum will get bleached it has to be Anodized Aluminum. night and day difference.