Dark spots / oxidation removed from aluminum siding - need help

I did a house with aluminum siding. There were some stains and non-organic growth on the siding (pollution contaminates due to being near a major airport) which the homeowner wanted me to remove. I was able to mix a hand sprayer with gutter grenade and water and it did okay using a very soft bristle brush. I was paying attention to the paint and surface to be sure the soft brush and mix was not removing paint.

So about 60% of the contaminates were removed but when everything dried I see these darker spots where I cleaned. I actually rehit the area with SH to see what would happen and not much changed. I REALLY rinsed the area and again, not much change.

I suspect I removed oxidation in those spots I treated and now it looks very different. The customer is not happy even though I warned him repeatedly that aluminum siding was delicate and the paint is oxidized. He pestered me over and over finding more and more spots he was not happy with.

Do you guys agree these dark spots are where the oxidation is removed?

If so, would the best approach be to remove all oxidation on those two sections of the house so they don’t stand out? Any other alternative approaches before I remove all the oxidation?

I just got some OneRestore and also NAPA auto Aluma-Brite. Would these be the best product to remove the remaining oxidation so the blotches don’t show?


Just for the future…I would only do aluminum if they are repainting only and that’s in writing. People want free paint jobs, you have to be careful. Cleansol BC does decent on oxidation.


Do the same thing you did before just every where it’s light in color.

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Thanks guys. I have done several aluminum sided homes with really good results. This one burned me because I was too optimistic on what I could remove.

Anyhow, Clean Blue - you are right, I am going to hit the entire side with CleanSol BC and pray evens out the appearance on that side of the house.

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