Black Streaks?

You’re wondering what those black streaks on your once-bright white gutters are, huh?  Wise Wash Power Cleaning has cleaned thousands of feet of gutters and is here to help you find the answer.  It’s easier to clean than you think if you just follow some simple rules. 

So it’s the beginning of Autumn and you’re trying to be a good steward of home maintenance by cleaning out your gutters and giving that home a nice new wash.  You’re all finished up but you notice that your gutters have black streaks on them.  “What is this nonsense?” you ask yourself.  How could dirt and algae still be present after a good ole’ house wash?  Wouldn’t the bleach (that you used responsibly, of course) kill all the algae?  Well unfortunately it isn’t that simple.  Although there is some debate in the industry about exactly what causes it, we at least know what fixes it.

 

Tiger Stripes

Those unsightly black streaks on your gutters are colloquially called “tiger stripes” for obvious reasons.  Although I’ve never seen a black striped tiger, I have seen lots of tiger striped gutters.  Older homes suffer from this phenomenon the most, but even gutters on a new home can suffer from these evil home-depreciating eyesores.  The longer these streaks stay on the gutters, the more likely it is that they will become permanent curb appeal killers.

 

Weird Science

No, not the awesome ‘80s sci-fi movie starring Kelly LeBrock, but instead about the science of bonding chemicals with electrons.  Most gutters in the United States are made of aluminum metals.  Aluminum is a versatile metal that is lightweight, durable, and will not rust (although it will corrode).  It can be fabricated easily and molded into just about any shape, including those fancy gutters your realtor said would increase your home’s value, but failed to mention you have to clean once a year.  But getting paint to stick to those gutters is a different story. 

Naturally few homeowners would purchase or install gutters that were bare metal.  Manufacturers don’t paint gutters with the typical brush or spray process because the paint will eventually peel or chip.  Instead, they must affix a dye to the metal by way of anodizing it.  According to anodizing.org, “anodizing is an electrochemical process that converts the metal surface into a decorative, corrosion-resistant, anodic oxide finish.”  The bare metal gutter is essentially dipped into a bath of acid electrolytes while an electric current is passed through it.  This process allows for the dye to be fully integrated into the metal of the aluminum, making it improbable that it will dry up over time.  See this video for an awesome demonstration of anodizing. 

This science backfires when mixed with rainwater, air pollutants, and sun rays.  When it rains, the water will drip down the front of the gutters collecting air pollutants, debris and other contaminants.  The contaminants will attach to the gutter oxidation in another process called electrostatic bonding and over time will cause those unwanted black streaks. 

Some professionals have said that the black streaks are also caused by the tar in asphalt shingles, but this isn’t likely because the streaks appear even on houses with metal or tile roofs.

 

Breaking The Bonds

So now that we know the most likely cause of “tiger stripes”, how do we get rid of them?  Wise Wash has tested many different types of cleaners.  A typical house wash mix containing bleach or other algaecides will not remove the streaks.  Algaecides are designed to kill organic matter only and have no effect on tiger stripes at all.  In fact, washing the gutters only makes the streaks more noticeable. 

There is no amount of water pressure from a power washer that will remove it.  Remember, this is a chemical bond, so we have to break the bond with another chemical.  Most household degreasers will work for this but I would caution using them without a good knowledge of the active ingredients.  Tons of damage can be done to the anodized (dyed) portion of the gutters if the wrong chemical or the incorrect proportion of chemicals-to-water are used. 

Most degreasers contain butyl, sodium hydroxide, or potassium hydroxide.  All of these chemicals will break the electrostatic bond.  Some more common store bought brands are LA’s Awesome, or ZEP, and Purple Power.  These brands can be used to remove the “stripes” from gutters, but they may also remove layers of oxidation that you want to keep.  It will look like the paint is coming off, but it’s really the oxidation layer of dye that was created in the anodizing process… not good! 

Since these brands aren’t specifically formulated for gutter brightening, extra care must be taken.  There are some commercial brands available that most professionals use to ensure the best possible clean and lesson the likelihood that the dye will be removed.  One of brands, Gutter Zap, has a great history of cleaning gutters and is biodegradable.  It’s a degreaser that’s specially formulated for gutter streaks and can be found at www.powerwash.com.

 

5 Steps to Brighten Gutters

1. No matter which degreaser you choose, always start by thoroughly watering down the surrounding vegetation. Depending on the heat, type of vegetation, and rain accumulation, some plants and grass will take differently to degreasers.  The last thing you want is to have clean gutters and wilting roses.  Spray down those gutters while you’re at it. 
2. Attach a soft bristled brush or mop to the end of an extension pole. Or grab a ladder that can remain stable while scrubbing from it.  Place the ladder where you want to clean trying not to scrape or damage the gutters.  There are attachments that will allow the ladder to rest on the roof to avoid gutter damage.
3. Apply the properly formulated degreaser to the pole brush/mop or rag that you’ll be using. You can also spray the gutter and then brush it but make sure the rag is damp first to avoid abrasive friction.  It’s always a good idea to test an inconspicuous area of gutters to see how they will react to the degreaser.
4. Allow the degreaser to penetrate the surface for a couple minutes. Do NOT let the chemical dry on the surface.  If the weather is hot, you’ll want to keep the surface damp and the dwell time to a minimum.  Colder temps will need more dwell time.  The streaks will disappear with relative ease.  Take extreme caution not to remove the layer of oxidation. 
5. Once a small section is cleaned, be sure to rinse the gutter and vegetation thoroughly before moving on to the next section. 

Final Words of Wisdom

Tiger stripes can be an eyesore to a newly cleaned home.  It’s not something most people notice until the rest of the home is cleaned.  But once you notice, you can’t look away!  Luckily Wise Wash knows how to get them back to white (or whatever the native color is) safely and without hassle to the homeowner. 

If you’re in the Wilmington, NC area and don’t have the time or the will to clean them yourself, please give Wise Wash a call at 910-789-2273 or send us a message.  We take pride in our knowledge and quality of work, and we’d be glad to provide a free quote to get it done right the first time.