I have to do a bid tomorrow for a house with brown gutters. The brown is the factory finish not painted. Will pot hydroxide work the same on the brown as it does on the white?
I clean a lot of brown gutters... Are you talking about "brightening" the gutters?
To be completely honest, I have NEVER had to do anything additional than my house wash to make brown gutters look perfect again. I love when I roll up to a house with brown gutters knowing it's one less part of the house I need to worry about.
I did a building 2 months ago that has brown gutters. Used regular house wash and hit them with a soft bristle brush since they were super nasty. Rinsed as usual and they looked great. Went to the building last week for something else, looked up at the gutters - still shining!!!!! Should be easy to quote this one.