I got a call from an owner of a office building complex and he wants us to wash his four office buildings I alread gave him a price and he accepted the price thanks to alot of research on this site. But I couldn't find a answer on what chemicals would work best. The buildings have a black streaks that run down them, rust stains by the pipes that protrude through the side of the buildings, and graffiti. I was wondering if anyone could give me an answer on what would work best on the above stains. I got pictures if that would help but there to good of a quality and I couldn't upload them but I will e-mail them if you guys need to see what im talkin about. Thank you in advance for any information you can give us.