The house is clean and the gutters still look dirty
This one comes up right after a wash, and the message usually reads the same way. The walls look great, the soffit came out bright, and the front of the gutters still has those dark vertical stripes running down them. From the driveway they're the first thing you see now, because everything around them got clean and they didn't.
The next thought is usually that something got skipped, or that the gutters are stained for good and the only fix left is replacing them. Neither one is true, and the reason is the interesting part.
Those stripes have a mechanism behind them, and once you know what it is, both the wash result and the fix make sense.
They're not mold, and they're not dirt
Look at a striped gutter closely. The marks run vertically down the face, they're fairly evenly spaced, and they're usually worse under seams and below the spots where water spills over the front lip. That pattern isn't how growth spreads. Growth follows shade and moisture and shows up in patches. These are lines, and they follow the path water takes running over the edge.
What's actually happening is that rain sheets over the front lip carrying fine residue with it, off the roof and out of the gutter itself. That residue doesn't just settle on the painted aluminum face like dust. It bonds to it. That's why scrubbing with soap and a brush barely touches it, and why the stripes are still in the exact same shape after a hard rain. The trade calls it tiger striping, which is as good a name as any for what it looks like from the street.
Why a house wash mix leaves them behind
A house wash mix is built to kill growth. It goes on the walls, the soffit and the fascia, it kills the algae and mildew living in and on those surfaces, and the rinse carries the dead growth away. On every surface that has growth on it, that works.
There's no growth in a bonded stripe. Nothing to kill. So the mix runs down the face of the gutter, rinses off, and the stripes stay exactly where they were. That's not a corner being cut and it's not a bad crew. It's the wrong tool for that particular mark, the same way a clean rag won't take paint off a wall no matter how many times you wipe it. It's one of the things on the list of what a soft wash will not fix. Everything else on the house wash came clean because everything else was growth.
Brand new houses get them too
Here's the part that settles the question of whether your gutters are failing. New construction gets striping. A house two or three years old, gutters still under whatever the builder put on, paint perfect, and there are stripes down the faces already.
That's the tell. If this were age, or rot, or a coating breaking down, a new gutter wouldn't do it. The stripes are about water running over an edge and residue bonding to a painted surface, and that starts happening the first rainy season the house sees. Old gutters have more of it because they've had more rain, not because they're worse gutters.
Why it looks like the gutters are failing when they aren't
Dark streaks on white read as damage to almost everybody. They look like water is getting in somewhere, or like the finish is breaking down from the inside, and that reading is usually wrong. The paint underneath a stripe is typically fine. The aluminum is fine. What you're looking at sits on top of the finish.
The other reason it reads badly is contrast. A striped gutter on a dirty house blends in. A striped gutter on a house that just got washed is the only thing left that isn't clean, so your eye goes straight to it every time you pull in. The gutters didn't get worse that day. Everything else got better.
Where it shows up worst
The heaviest striping tends to sit under a valley, where two roof planes dump into one short run of gutter, and along the front elevation where the longest unbroken run of white is. Anywhere water regularly comes over the front edge instead of going down a downspout, you'll see it darker.
Trees make it worse. A house under oaks gets more debris in the gutter, which means more spilling over the lip and more residue riding down the face with it. That's also why one side of a house can be striped badly while another side barely shows it, on gutters that went up the same week.
Taking them off is a separate step
Because the stripes are bonded rather than sitting loose, removing them takes a different product than a house wash mix, applied directly to the gutter face, given time to work, worked over the surface, then rinsed. It's hands on and it takes real time per foot of gutter.
That's why it's a separate line on a job rather than something included by default in every wash. It isn't a case of holding something back to sell later. It's genuinely a different task, and plenty of houses don't need it, so it doesn't belong bundled into every quote. If your gutter faces are striped and you want them handled, say so specifically when you ask about pricing, because a standard house wash quote is not going to include it. It sits alongside a gutter clean out rather than inside a wash.
What this does not do
Getting the stripes off does not stop them coming back. Rain keeps running over the front lip, so the same process starts again, slowly. It'll be a long while before it's noticeable, and it's not something you'll be dealing with every season, but nobody should tell you it's permanent.
It also doesn't repair anything. A gutter that's sagging, a seam that drips, a section pulling away from the fascia, a downspout that's come loose: cleaning the face changes none of those. Very old gutters that have oxidized badly may not come all the way back to looking new either, and if photos show that's the situation, you'll hear it before anyone takes the job rather than after. No claim is being made here about how long any of it lasts. The stripes come off. That's the claim.
Common questions
Do I need new gutters?
Almost certainly not for this. Striping is a surface issue on the paint, not a sign the gutter is failing. Replacement is a conversation about leaks, sagging or damage, none of which are what those vertical lines are telling you.
Why didn't my house wash take these off?
Because the wash mix works on growth and the stripes aren't growth. The walls and soffit came clean because algae and mildew were what was on them. The gutter faces were carrying something bonded to the paint instead, and that needs its own step.
Can I scrub them off myself?
You can try from the ground on a single story with a soft brush and see how much comes off, and honestly, on light striping some of it will. Stay off ladders for it. The heavier bonded striping usually doesn't move for soap and effort, which is the frustrating part people report after spending an afternoon on it.
Send a photo of the gutter face
Stand back far enough to get a run of gutter in frame, take one photo, and text it in. You'll get a real number back and a straight answer on whether the striping is the light kind that comes off easily or the kind that needs the full treatment. No appointment, nobody coming out to look first. Call (941) 257-8624 between 8am and 7pm Monday through Saturday if you'd rather ask than type.