What Causes Black Streaks to Appear on Gutters?

Ever noticed black streaks on gutters? These are more than just grime and dirt. Gutter Helmet, the trusted provider of the best gutter guards on the market, explains what these unsightly marks are and how you can get rid of them effectively.

How Black Streaks Appear on Your Gutters

The ugly black stains on gutters often referred to as “tiger stripes” or “zebra stripes,” are vertical stripes of dark gray or black matter forming on the front of aluminum gutters. These are the consequence of a chemical interaction between the pollutants and the gutter material.

There are two potential reasons why these streaks appear:

1. Raindrops often come with airborne pollutants. Once they hit the front of the gutter and roll down, the pollutants are left behind on the aluminum gutters. Electrostatic bonding occurs, causing the fine particulate matter to embed on the surfaces. That’s a primary reason why simple power washing just won’t cut it.
2. Water runoff overflowing to the side of the gutters carries asphalt from the roof shingles. These, too, bond with the aluminum gutters chemically, resulting in those tiger or zebra stripes.

The chances of black streaks appearing on your gutters will depend on several factors, including the quality of the outdoor air and the presence of pollutants from sources such as motor vehicle exhaust and nearby construction activity.

How to Get Rid of Black Streaks From Gutters

Conventional cleaning agents can help remove standard dirt, algae, and grime off gutters, but not black streaks. These would require specialized cleaning solutions, which may contain harsh chemicals. Wearing protective gear to protect your eyes and skin is important before starting the task. Cleaning tools like a rag, sponge, or cloth can be used but if you intend to use a brush, make sure its bristles aren’t hard or made of metal because they could damage the gutter surfaces.

To ensure your safety, however, you’re better off leaving this cleaning job to the professionals. Alternatively, if you want to minimize the need to clean your gutters, you can always turn to Gutter Helmet for exceptional gutter protection solutions. Give us a call at (800) 824-3772, or fill out this contact form to learn more about what we can do for you.