This is due to a phenomenon called electrostatic bonding.
Electrostatic bonding gutters.
Rinse it off and let those gutters shine.
When cleaning gutters it is important to break the bond between the dirt and gutters.
Once the bond is broken only then can you easily clean gutters and the pesky tiger stripes that occur.
Use gutter zap on your new applicator to apply it to the exteriors of gutters.
The dark marks on gutters are caused by the electrostatic bonding of dirt grime and acid rain runoff.
The contaminants will attach to the gutter oxidation in another process called electrostatic bonding and over time will cause those unwanted black streaks.
You can adjust the formula s strength by diluting it either half and half with water or one part gutter zap to 3 parts water.
The black streaks are a result of electrostatic bonding of tar asphalt from roofing material and other debris to aluminum metal material.
The black stripes also known as tiger stripes that appear on the outer surface of gutters are the results of water run off which causes particles from algae roofing materials or the air to cling to the surface by the process of electrostatic bonding.
Over time these stains get embedded into the oxidized paint on the gutters.
Gutters are metal and as such have an electrostatic bond which attracts atmospheric dirt.
Streak getter will break down this bond which will allow you to remove the unwanted streaks off your aluminum gutter with little effort no scrubbing.
That s where the problems start and they make themselves known in the form of black streaks.