A few weeks ago I washed a house and white staining appeared on the siding when everything had dried. Went back today and rinsed, soaped, and rinsed again liberally and staining is still there. Siding is only two years old with that side facing the north so minimal oxidation is present. You can only see it when looking at an angle; when looking at it straight on, you can’t see it. Has anyone ever had this happen? If so, what can we do to fix it? Thanks in advance!