DIYbanter - View Single Post

wrote:
We have a new, black aluminum fence. Portions of it have what looks
like soap residue on it - white blotches. What is causing the spots?
Is the fence material inferior?

if it's bare aluminum, what you're seeing is aluminum oxide. Aluminum
doesn't rust like iron, but it DOES oxidize. I'm guessing you have
aluminum that's anodized to give it the black color rather than painted
and that the anodizing has some small defect areas or pinholes that
aren't covered. You might try to get some warranty from the installer
(or supplier if you installed it yourself).