Alum Siding Issue

[John Doherty 126]

Did an alum sided house today, this popped up as soon as my mix hit it, it's the top of the wall, under an overhang, and down the first couple of rows of siding.

It didn't pop up anywhere else on the house.

Rinsing, recleaning, and even a shot of oxalic did nothing to it.

Any help appreciated.

[A C F 14]

Hard for me to tell, but it almost looks like something ate the paint from the aluminum. Are you sure it is not simply bare/corroded aluminum you are looking at??

I hope I am wrong, but.....

[john@AEC 37]

Hi

Has the colour come off? leaving undercoat/bare aluminium.

What did it look like before? was it covered in mould? perhaps the mould has eaten into the colour coating.

I can't imagine that regular house wash mix would damage siding in good condition. At least it's not next to the front door!!

[John Orr 206]

It looks to be a really bad case of oxidized aluminum. If you run your hand over the spots, are they raised? If so, then that's what it is. They were there before you cleaned, but may have been hidden under dirt. I have noticed this issue on older aluminum siding as well as newer trim - usually in protected area (under eaves, porches, etc.).

[Rick2 42]

John's right, oxidized aluminum. I see it quite a bit here in New England.