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What are those black streaks on my gutters?

Updated: Feb 23, 2019

The exterior of your gutters get dirty. Sometimes it’s just an algae that can easily be removed, but sooner or later those black stripes will appear. Commonly referred to as (tiger stripes) because of their apperience. You’ll find a lot of controversy over exactly what causes it. Some say it’s an electrostatic bonding from tar on your roof, yet you’ll find them on homes with metal or tile roof as well. Some say it’s the zinc in the metal of the gutters and as water runs down it‘s eating into the painted finish that was orginaly applied. I’ve researched and found many possibilities to be the actual cause. I would say the zinc is very possible as aluminum gutters can have some zinc added into the metal. Zinc strips are also commonly added to roofs of northern homes to help slow down moss growth. There’s also many things on your roof that may be made from lead. Lead has been used on roofing for centuries and is one of the oldest flashing materials. So we now have several types of metal mixing together, along with rain water that may contain acid. Did we just start some kind of scientific experiment? So who really knows what causes it? I‘ve come to the conclusion it’s definitely some type of chemical reaction that’s caused damages to the finish of the gutter. The debate and controversy really didn’t help solve the solution, but at least we now know the finish is indeed damaged. So how do we get rid of it? There’s many products out there that claim, “spray on, wipe off)”. I’ve tried probably everyone over the years, don’t buy it. If it sounds to good to be true it probably is. Some people choose to paint over the gutters. Which definitely covers the stripes, but usually looks kinda cheap, with brush lines and a dull finish. We also find that painted gutters are harder to clean and maintaIn. The conclusion to this subject and how we’ve found to remedy the problem, we call Gutter Restoration. In this process we use a butyl based product mix just to the right strength to lightly loosen just a tiny bit of the finish, and blend it all back together. This is a commercial product but there are some household cleaners that can be used for the DIY’s (LA Totaly Awesome Cleaner) from the dollar store is one, just be very careful if you choose to try it yourself, the finish can easily be taken completely off. Start with a mild mixture applied to a wet surface and increase slowly as needed, rinsing frequently and not allowing product to dry. It’s a rigorous process that involves a lot of brushing, scrubbing, rinsing and appling, over and over again. The results are well worth it and your gutters will look new again. Some areas may require a light touch up with a specially made gutter paint. You’re local hardware store may carry this for you DIY’s. It will not be located where the paint is but in the gutter section. Yep the gutter contractor that installed the gutters most likely used the same paint to covered up any of their mistakes. I hope this information was educational and helpful and you soon have some pretty sparkling white gutters. Don’t have white gutters? The process works the same on other colors of aluminum gutters as well.

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Always call a roof repair company to clean gutters, remove all the debris (leaves, dirt, other plant matter) so that water can flow appropriately to down pipes and drain away from the house.

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