I stood in a driveway in Cherry Hill last week while a homeowner pointed up at her gutters and asked if she needed new ones. Not cleaned. New. The black streaks running down every downspout looked like rust, like something failing. They weren't. The gutters underneath were fine.
That mix-up costs South Jersey homeowners money every year. Some replace gutters that had another decade left in them. Others book a standard house wash and can't figure out why the black stripes are still there the next morning. Both mistakes come from the same misunderstanding about what's actually on the aluminum.
It's not dirt. It's the metal itself.
Aluminum reacts with air over years and forms an oxide layer. On a gutter, that reaction shows up as vertical black streaks running from the top edge down, following wherever water sheets off the roofline. It's the same reaction that dulls a bare aluminum boat or trailer left outside season after season. Different shape, same chemistry, and it builds slowly enough that most homeowners don't notice until the whole run looks striped.
Soap and rinse water clean surface dirt. They don't touch oxidation, because oxidation isn't sitting on the surface, it's a chemical change in the metal itself. Gutter cleaning clears leaves out of the trough and confirms the downspouts drain. Gutter brightening is the separate step that strips the oxide layer with an acid-based treatment and brings the aluminum back close to its original finish.
Why DIY attempts usually make it worse
I've walked up to more than one South Jersey house where the owner tried bleach and a scrub brush first. Bleach doesn't break the oxide bond, so the streaks stay, and the runoff can kill the grass or the mulch bed underneath. A pressure washer wand aimed at the gutter face just pushes dirt around. It can't touch oxidation either, and too much pressure at the wrong angle dents the aluminum or drives water up under the fascia.
The chemistry that actually works is acid-based, and it has to be handled with some care. Too weak and the streaks barely fade. Too strong, or left to dwell too long, and it etches the metal or drips onto the siding and stains that too. Service · learn moreGutter BrighteningAcid-based brightener, hand-applied section by section, siding rinsed the second any drip lands. Fifteen years, no damage.See the page →
What I actually do
- Clean first. Gutters get hand-cleaned and the downspouts flushed to confirm they drain. No point brightening a gutter that's still full of last fall's leaves.
- Protect what's underneath. Landscaping gets tarped before a drop of brightener goes on, the same way I pre-wet and cover flower beds before a house wash so overspray never reaches a root system.
- Apply, dwell, rinse. The brightener goes on section by section, gets a few minutes to break the oxide bond, then rinses clean. Any drip on the siding gets rinsed off immediately, before it has a chance to sit.
Done right, the gutters come back close to the day they were installed. Done wrong, you've traded black streaks for etched aluminum or a stained wall, which is a worse problem than the one you started with.
How long it lasts, and what slows it down
Brightening typically holds for two to four years before the streaking becomes noticeable again, depending on how much sun and rain the gutter line takes. A shaded run on a wooded lot in Moorestown or a tree-lined street in Voorhees tends to hold up longer than a south-facing run that bakes all summer. Keeping up with regular gutter cleaning, twice a year is the standard here, slows the oxide rebuild too. Debris sitting in the trough holds moisture against the metal longer, and moisture is what feeds the reaction.
What it actually costs
Gutter cleaning across South Jersey runs $150 to $375 depending on the size of the house and how many stories the ladder work covers. Brightening gets quoted separately during the same free walk-through, since price depends on how far the oxidation has gone and how many linear feet of run you have. I look at both while I'm there, so you get one firm number instead of two visits and two guesses.
The honest version
I'm the guy on the ladder myself, every job, for fifteen years now. That's not a sales line, it's why I can tell a homeowner in Cherry Hill or Merchantville exactly what's wrong with their gutters instead of guessing. 4.9 stars on 28 Google reviews is the record of showing up and doing it the way I just described, section by section, no shortcuts. You can read the origin story on my about page if you want the longer version.
If your gutters have gone from streaky to embarrassing, I'll take a look for free. Fifteen-minute walk-through, a firm number for cleaning and brightening together, and I'll tell you straight if brightening is worth it yet or if you've got another year in you. Get an estimate or call (267) 235-1885.