Hey Chris,..what acid did you try on the red dirt? Acids are usually a requirement for removing these type of stains. They need to be chemically altered so to speak. Typically oxalic will remove red clay stains,..or even diluted hydrochloric acid. May take a few applications and extended dwell times. If the aluminum is badly oxidized,..I would do a test area,.and try and stick with oxalic at about 4-6 OZ. per gallon,..applied direct.

Jeff

It was recommended to me on another thread to use Aluminum Brightener either with or without HF acid to remove grime and oxide from aluminum siding. I decided after all to pass on the job so I did not try the stuff.

www.advantageroofcleaning.com/soft-washing-exterior-siding-cleaning/

Thanks guys for the info I tried this red dirt remover a customer mine gave me for a demo. It's was a very week acid and as you see a lot of areas we're very stained. I think I'll try oxalic next time. The customer was still happy because I did inform him prior that sometimes the red dirt won't come out all the way. The house was really bad but is kinda hard to see in the pics.

Chris, Check with Michael Wedge. Good guy and he lives in HI. He has several posts about the red clay and knows what works best.