I just wanted to start out by saying that I received my certificate for Master Certified Applicator this past week and I'm really excited to have that achievement in my pocket.
I tackled my first aluminum roof Friday and I had an issue I'm hoping someone can help me with. I posted a picture to show what I'm asking about. There was these black streaks that I assumed by taking the modules that I'd hit with a 2% SH solution, let it dwell, then come back and hose it off. I hit them three times and it wasn't coming off. I then agitated it and I got some more to come off but not all of it. I upped my SH to 3% and hit it again and it hardly helped. I tried gutter zap with agitation and it helped but couldn't get all of it. Then I tried barkeepers friend and with a lot of scrubbing I finally got it to come off. When I was scrubbing on it there was a dark red almost purple hue to it. Can anyone tell me what this stuff was and maybe give me some suggestions on how to handle this? We have a lot of aluminum roofs down here in SW Florida and I'm sure to come across this issue again. Thanks for your help
We really don't get it that bad in the NorthEast, especially on metal, but I know the Florida & Caribbean guys might be able to chime in better. Looks like really funky GM and algae. I would bump up the mix and the Green Wash slightly and just increase dwell time.
I'm using 10.5% SH but I purchased it from a new supplier and I'm not sure if it was fresh to them. I had bought it the day before I tackled this job. I never had an issue with 10.5% when I use it to make a 4% mix to spray tile roofs. I'll get in touch with Ray Burke and ask him. Thanks for pointing me in the right direction.