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How Do I Remove Those Ugly Black Stripes on Gutters?

Often referred to as “tiger stripes” or “zebra stripes” by industry members, those ugly black stains on gutters are the result of a chemical reaction between the asphalt in roof shingles and the anodized aluminum in gutters. Because they are not just stains, traditional house washing chemicals used for removing mold, mildew, and other contaminants won’t budge them.

The black streaks are caused by an electrostatic bond that must be broken in order to remove the stain, very similar to the way that road film sticks to vehicles. However, the gutter manufacturer anodizes the aluminum in order to make the paint stick, and using too strong of a chemical can take the paint off the gutter. You should always test your mix in an inconspicuous area to make sure you aren't removing paint. 

We recommend specially-designed products like Gutter Zap and Gutter Butter that are made to break that bond and remove those stripes. (We’ve also found that adding 4 oz. of Gutter Butter to your housewash mix will melt spider webs on contact!)

The dilution for depends on the oxidation level on the surface. The key is to keep all surrounding surfaces wet. Apply your gutter cleaning product in sections by scrubbing in with a brush (we recommend the ), then allow a short dwell period of no more than five minutes. Then simply rinse with a garden hose that has an attached. Typically, one application is enough.

For applying the products, the Bi-Level Brush is an excellent choice to use in conjunction with an extension pole to reach most gutters fro the ground.

Gutter Butter

Gutter Butter is a biodegradable, concentrated cleaner that's effective in removing oxidation in a number of surfaces, including gutters, siding, metal roofs, etc . We've also found that when added to your house washing mix, it melts spider webs on contact!

To use: 

  1. Dilute as recommended. (10:1 for gutter brightening. Vinyl siding and roof restoration, 24 ounces per gallon. Start low and increase as needed.)
  2. Pre-wet the surface and surrounding areas prior to use, paying special attention to windows.
  3. Apply with low-pressure mist. The ProTool Sprayer is a good option here. 
  4.  Brush if needed. 
  5. Rinse thoroughly with water. 

Additional Tips: 

  • Always test in an inconspicuous area before using
  • Do not allow Gutter Butter to dry on surfaces
  • Use only in temps above 50 degrees F
  • Do not use on polished aluminum
  • Wear appropriate PPE when using, including gloves and eye protection

Gutter Zap 

Gutter Zap is another effective option for removing those black streaks from gutters caused by the electrostatic bonding of tar and asphalt from roofs.

Gutter Zap is concentrated and can be diluted either 2:1 or 3:1 (water to chemical ratio). Apply with a sprayer, agitate with a soft brush if needed, then rinse off.