Friday, March 24, 2023


Black streaks: Where do they come from? How to deal with them?

By Dicor Corporation
Many RVers have experienced black streaks down the sides of their RVs, but where do they come from and how do we deal with them?

Where do they come from?

All kinds of airborne pollutants land on your RV roof, including plain old dirt and mold. Many pollutants have properties that help them stick around. When a good rain comes, or a good roof cleaning, they can get dislodged and wash down the RV’s sides, only to stick around there, too.

On aluminum-sided RVs, such dirt and mold can be aided by the porosity of some kinds of aluminum that exude certain oils, which further help these pollutants bond. If not addressed in a timely fashion, they can really get baked in.

You can also have white streaks of oxidized powder that mixes with dirt and reacts in a similar way when it is washed off the roof and onto the sidewalls. One myth to explode, though: Rubber roofs DO NOT cause black streaks.

How do you get rid of black streaks?

The good news: There are a variety of cleaners on the market that can probably help you out. You just need to be sure they are compatible with your sidewall material, paint and decals. Look for manufacturer guidance. If there’s one you think might work, test it on a small area and see how the material reacts after a couple days.

When the roof is thoroughly dry, for added UV protection you may want to use a roof protectant like Roof Gard, a spray-and-wipe-on UV inhibitor that reduces oxidation and keeps other pollutants from getting a good grip on your roof.

Now that you know a little more about what creates streaking and how to avoid it, we’re sure you’ll enjoy lots of streak-free RV fun.

Here are more Dicor RV roof products on Amazon.

Related information:
Tips on cleaning your RV roof
Preventing winter RV roof damage



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2 years ago

Black streaks can be nearly eliminated with the addition of stick on vinyl gutters and corner extensions. The few that do form from over the door or window gutters can be easily removed with “Simple Green” in a spray bottle and a soft cloth. Works great on my Class A fiberglass caps and sides and I haven’t noted any damage to any decal either.

2 years ago
Richard Hughes
2 years ago

When we bought our last rig we fell for the dealer’s pitch for a “special coating” to repell dirt and protect the finish from the sun. We have had the RV for two years now. It had a few streaks, so I decided to wash it myself. Much to my amazement, as the water hit the sides the streaks disappeared and the water slipped off, leaving the surface dry. I don’t know if it was the “special coating” or good material, but the coach looks brand new. Moral: It wasn’t worth what I paid, you can get a can of Liquid Glass Auto Polish, do it yourself or hire someone to get the same result for around $30, plus labor.

2 years ago

Aluminum exudes oil? I don’t think so.

Ed D.
2 years ago

My suggestion for getting rid of Black Streaks is to use “Beast Wash” by “Wademade”. Use full strength in a Spray Bottle. Spray the streak and let it set for about a Minute. Then use a Sponge or a soft bristle Brush to wash it off. We purchased a brand new Class C in 2016 and the Black streaks from sitting in the lot were bad. We tried Camco Black Streak remover and it did nothing. But when I used Beast Wash, it took them off with little effort. It is good for Cars, House sides, RV’s and any other cleaning job you might have. It is a little pricy but worth every penny!

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