Quick question for those doing a lot of house washing with downstreaming or soft wash setups.
Lately I’ve had a few jobs where aluminum gutters come out looking clean, but after a few days they seem to show oxidation or striping again faster than usual. Not sure if it’s something in the mix, dwell time, or just the older gutters reacting to the wash.
I’m using a pretty standard SH-based mix and rinsing well, so I’m trying to figure out if this is more chemical-related or just material condition showing through after cleaning.
Has anyone adjusted their process to prevent this or seen the same thing in humid/coastal areas?
I’m just a part timer, but a HW mix won’t remove oxidation at all, unless you are blasting it hard with pressure (the pressure will knock off the chalking). The black streaks, also known as tiger stripes, are not normally removed by HW mix. I brush most of my gutters and that won’t remove the tiger stripes either. There are several things people use to remove the tiger stripes, mostly these are acid based products. Search the forum for tiger striping/tiger stripes and see what the wizards have to say. If a gutter is already oxidizing, removing that oxidation doesn’t stop the process from occurring again. Research photodegradation and photo-oxidation if you are interested.
Oh, and be careful, if you get too aggressive you will be painting gutters.
I’m still seeing the same thing on a few of these jobs. The gutters look fine right after the wash, but after a couple of days the oxidation lines start showing again. Starting to feel like it’s less about the rinse or dwell time and more about the condition of the aluminum itself reacting once it fully dries out.
I also asked around a bit with a local cleaning company in Palm Coast, and it seems like others offering cleaning services in Palm Coast have run into similar situations, especially in more humid or coastal areas. I’m going to test a slightly lighter mix on the next few jobs and see if it changes anything.
I’m confused. Are you trying to remove oxidation, or are you trying to remove tiger striping?
If you wipe your finger/hand on an oxidized white gutter it comes off white, same thing with brown/tan etc. If you rub your hand on a copper gutter with a patina, you will get some of the patina on your hand. If you are trying to remove the black lines on white gutters, that is the tiger striping, not oxidation. If the paint is missing, SH and a hose isn’t fixing that.
SH will not remove oxidation and it will not remove the black lines. I don’t care what percentage you are using. If you spray a white gutter with black lines with SH then brush it hard with a bilevel brush (not a stiff deck one) the black lines will still be there…maybe…maybe a bit subdued. Once completely dry, the black lines are not as subdued when wet and become pronounced again. Especially with the shiny newer aluminum gutters. Most of the time the black lines are a combo of different things, but according to the googly :
Causes of Tiger Striping
These vertical stains are not usually caused by a defect in the gutter’s paint or finish, but rather by external debris and chemical reactions. Common culprits include: [1, 2]
Organic Debris: Algae, mildew, pollen, tree sap, and leaves that settle along the top edge of the gutter. [1, 2]
Airborne Pollutants: Soot, chimney emissions, and general air pollution that collect on your roof and wash down. [1, 2]
Oxidation: When the protective clear coat on aluminum gutters begins to age and oxidize, it creates a chalky surface that easily traps dirt. [1, 2, 3, 4, 5]
Overflow: If gutters are clogged and water spills over the front lip instead of flowing through the downspouts, it leaves behind concentrated dirt trails. [1, 2, 3, 4]
Read the SDS of the product you are going to use. Some have acids in them, some have potassium or sodium hydroxide (paint strippers), and some (lol) are nothing more than soap and water.
It is a balancing act, you can’t make super worn gutters look good, there is hardly any paint left.
I learned something from this. I used to think SH would take care of almost everything on gutters, but it makes sense that oxidation and tiger striping are two completely different issues. That’s a really helpful explanation. Sometimes the problem isn’t the cleaning process at all, it’s just the condition of the gutter itself. Setting the right expectations with customers is probably just as important as using the right products. Thanks for sharing the details. This was a good read.
I am starting to notice an interesting pattern with tiger stripes. Keep in mind this is my first full professional year, so not a ton of first hand data…
I had a customer complain about the tiger stripes after. Gave the standard explanation and she said, “but they’re new gutters” (you know, which usually means 5-10 years old lol). However, these gutters actually did look relatively new. She didn’t push it, but it got me thinking… I started looking for clues with houses that had tiger stripes. Clogged gutters are obvious, but air pollutants? Really? We don’t live in Shanghai, not buying it for newer gutters to get medium dark tiger stripes while gutter finish remains pristine. Obviously wasn’t oxidation either. Thwee gutters weren’t very bad organics wise.
Most roofs here are asphalt shingles. Check the downspouts on future houses and sure enough, excessive asphalt shingle granules. I’m betting old roofs that are loosing their protective granules have the petroleum based asphalt shingles breaking down in the uv rays and the rain washing that breakdown into the overflowing gutter.
I feel it’s a very strong theory and would love to hear what .ore experience guys think before I start blabbering this out to customers lol.
Good selling point on a roof wash is that 30 to 40 year shingles are based on proper maintenance. Cleaning is maintenance. Roof washing can also help protect your gutter investment!
You’re exactly right. Tiger stripes are primarily caused by roof runoff carrying dirt, pollen, asphalt shingle granules, and other environmental contaminants over the face of the gutter. I’ve seen them develop on new homes within the few months, especially where construction dust, heavy pollen, or frequent runoff are factors. The more contaminants in the runoff and the more often the gutters get wet the faster tiger stripes tend to appear.
I’ve found the most efficient way to deal with them (while significantly decreasing the chance of stripping down to aluminum) is to use ZEP Heavy-Duty Citrus Cleaner. I usually start with a 50/50 dilution, apply it with a spray bottle, pump sprayer, or brush, scrub as needed and let dwell a minute or two, and rinse thoroughly.
