I washed a church the other day and am disappointed in the outcome. This was built in 1970 and I was told it had never been washed before. I am wondering if I am dealing with 50 years of fallout around the bump-outs and if anyone has any ideas on what to use to get them clean. I used a 12V with about 3.5% and hit it several times. When some of the stains were still visible even before drying, I hit them with a pump sprayer using about 8% and it didn’t do anything. I tried some OX and nothing. Tried a small area with EBC and nothing. Is it just that this is stained beyond saving? The maintenance guy seemed happy overall, but I’m not. We did talk about the stains before hand and I warned him that I didn’t think they would all come out. He said worst case is they have to paint it. I am just hoping someone has come across this before and has an idea for me to get it looking better.
I can’t really think of anything that we would wash with 8%, that’s a very strong mix, it’s safe to assume if you were hitting the wall at 8% and nothing was happening that it’s beyond cleaning and needs new paint. I think it came out great for 50 years of weathering, i would be happy with that.
It’s needs a paint job. 8% is really hot, pray for those plants 
Yeah, I’ve only went that hot on a gutter or two but really try to keep it 6% and under for the really bad spots. I guess frustration got to me and I thought nuking it might help. LOL. I know it looks better but the perfectionist in me has a hard time dealing with it.
It was from a pump sprayer just on the bad spots so with rinsing I think I’m ok. They do have a crap ton of roses out front. The guy told me he wasn’t concerned if a few were killed. I watered before during and after.
