Those dark vertical streaks running down your gutters are not dirt a hose will rinse off. Here is what tiger stripes actually are and why removing them takes gutter brightening, not pressure.
You wash the house, the siding looks bright again - and the gutters still have those dark vertical streaks bleeding down their face. It is one of the most common frustrations we hear across the Upstate: the whole exterior looks clean except the gutters, which somehow stay stained no matter how many times they get rinsed. Those streaks have a name - "tiger stripes" - and the reason a hose never touches them is that they are not really dirt. Here is what they actually are and what it takes to get them off.
The black or gray streaks running down the front of aluminum gutters are not loose grime sitting on the surface. They are a bonded film of airborne pollutants - carbon from road traffic, pollen, and the fine granule grit that washes off asphalt-shingle roofs - that has electrostatically fused to the oxidized aluminum. Every time it rains, water sheets over the front lip of the gutter carrying that fine debris, and as it dries it leaves the residue behind in vertical drip lines. Over months and years those lines build into the dark tiger stripes. Because the staining is chemically clinging to the oxidized metal, not just resting on it, plain water slides right past it.
Homeowners understandably assume the gutters will come clean with everything else during a house wash. But the soft-wash solution that dissolves algae and mildew on siding is not formulated to break the electrostatic bond holding tiger stripes to aluminum - it lifts organic growth, and tiger stripes are mostly inorganic. A garden hose does even less; it just re-wets the same debris that caused the stripes in the first place. Removing them takes a dedicated gutter brightening solution - a mild surfactant-and-acid blend made specifically to release oxidation staining from aluminum - applied to each gutter face and hand-agitated so it actually contacts and lifts the bonded film. That hand-work, gutter by gutter, is why brightening is its own service rather than something a house wash sweeps up for free.
A few things make the Upstate a tiger-stripe hotspot. Heavy tree cover means constant pollen, leaf tannins, and organic dust washing across the gutters all season. The humid climate keeps that film damp and reactive longer. And the region's asphalt-shingle roofs shed a steady trickle of fine granule grit that runs straight over the gutter lip with every rain - one of the biggest contributors to the staining. The same shaded, damp conditions that give Upstate roofs their black streaks feed gutter staining too, which is why homes under mature trees around Easley and the foothills tend to show the heaviest stripes.
The instinct is to blast the stripes off, but high pressure is the wrong answer twice over. First, it does not work - the staining is bonded chemically, so pressure knocks off only the loose surface film and leaves the tiger stripes right where they are. Second, gutters are thin, formed aluminum: a close-range pressure tip dents and warps the face, can spring the seams, and drives water up under the shingles and behind the fascia. The right approach is chemistry, not force - the brightening solution does the work, and the gutter surface is never at risk. If a company arrives ready to pressure-wand your gutters clean, that is a warning sign.
It is worth being straight about what this service does and does not do. Gutter brightening is cosmetic - it restores the color of the gutter face so the exterior looks finished and the gutters match the trim again. It is not the same as a gutter cleanout, which is clearing leaves and debris out of the trough so water flows. A home can have spotless white gutters that are still clogged, and clean-flowing gutters that are streaked black. If your gutters are sagging, overflowing, or pulling away from the fascia, that is a separate repair. Brightening simply makes the outside of the gutter look as clean as the rest of a freshly washed house.
Because so much of any job is the trip and setup, the least expensive way to brighten gutters is to fold it into a visit that is already happening. Tiger stripes sit right below the roofline and directly above the siding, so brightening the gutters at the same time as a full house washing is where the finished, matching look comes from - clean siding under stained gutters still looks half-done. Homeowners across Simpsonville and southern Greenville County tend to bundle the gutters into their annual exterior wash rather than booking them alone. For how the surfaces price out together, see our Greenville pressure washing cost guide.
Tiger-striped gutters are one of those problems that quietly drag down the look of an otherwise sharp house, and they are genuinely satisfying to fix - the difference between streaked gray and clean white is dramatic from the street. If your gutters have gone dark while the rest of the exterior looks fine, a gutter brightening in Greenville will pull the staining out at the source. Get an upfront quote and we will tell you honestly what the gutters need - and whether bundling them with the house wash is the smarter call.
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