We have an aluminum siding travel trailer. We can't get rid of the black streaks. We have tried the LA Awesome cleaner with a pressure sprayer and had no luck. Any suggestions??
Cold water Tide powder. Just add a 1/2 cup to a bucket of cold water, using a long handled car wash brush, soak the area, let sit for 10 minutes, reapply, let sit for a few more, then gently scrub with the car wash brush. Rinse and black streaks should be gone. I've used it for years. works great! Also, remember to wash your roof a few times a year to reduce the dirt that causes the black streaks. Use tide the same way.