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. Gutter brightening removes the dark layer of oxidation and/or striping effect and is considered a restoration process as it restores gutters to their original white color. As for our house washing we use a low-pressure biodegradable detergent that kills and removes stains such as mold, mildew, fungi, and bacteria, while loosening the grip of dust dirt and cobwebs on your exterior surfaces. All of this is done with low pressure and last 3-5 times longer than pressure washing.