Why do I keep etching driveways?

Do you have a pressure gauge? Put it between end of hose and surface cleaner, then you’ll know what you’re actually getting.

I was getting 2000 Psi, checked with pressure gauge. I believe I said that in the original post

Where did you have the pressure gauge hooked up? Was it on the unloader or at the end of the line before the surface cleaner? Something isn’t adding up here, and the only way to really figure it out is by testing your equipment. Find a friend who will let you test on their driveway… pre-treat it with 2-3%, run the surface cleaner with 25025 tips in both directions going slow and overlapping each pass a little (from the street to the garage, and then from the edge of grass to the grass on the other side), rinse it all down as you go, see if you have any lines left over, if you do post-treat. Take before and after pictures up close and overall and let us know how it went. I’m still in the camp that those stripes are leftover dirt that wasn’t removed and not etched.

I’ll agree, the first picture, yes not etching. However, the other cases, on my street, are confusing me. I posted that second picture on a facebook group and everyone agreed it was etching. Pressure gauge right before the surface cleaner.

This isn’t making sense. I run a 4 gpm machine and use 2502s and checked with a gauge, I’m right at 3000 psi at the surface cleaner. I’ve been running this setup for 4 years no with no issues at all. Never etched any concrete and I rarely ever have striping. I don’t post treat either, just a 1% pretreat and go slow.

How close are your nozzles to the ground? I have mine as high as I can get them on my GP Hammerhead SC.

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So, you checked your pressure before the SC which told you how much pressure was going into the gun on the surface cleaner. Do you have a strainer on that inlet? Have you check to make sure there are no clogs in your line or in your nozzles? Those things would change the pressure. You need to check the gun on the SC too. One time I found leaves in my SC gun, don’t ask me how that happened. All rolled up like a joint. It changed the pressure significantly.

Use deductive reasoning and you will find your solution. "When you have eliminated the impossible, whatever remains, however improbable, must be the truth ".

My “how did I miss that” moment was a few years ago. Holes in your tips are shaped like race track ovals, the shape needs to run parallel with the bar and make sure the tips aren’t clogged.

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All good ideas. Strainer on the inlet? I’m pretty new to this, so not sure what that is.

These are pictures of what I did today. Switched back to 25025 tips. 1% pre treat. Went slow. Only one pass. No lines to be see. Then, I post treated with 3% and lines showed up? What the hell. So I rinsed all the SH, and the lines either completely went away or faded in most places. And this gave me the idea, is me post treating making my lines show up like this? That makes no sense. The before/after picture shows the post treat on the concrete (line appeared) and what it looked like after I rinsed the post treat (line disappeared). Any insight would be appreciated.

That’s a good point, perpendicular to the bar and the water is like a knife blade. Worth him checking

sorry, I meant to say filter. They sell them and tell you to put it on before your SC. If you have a filter off your tank it shouldn’t be an issue.

If it’s clean, absolutely no need to use 3% unless you have embedded algae.

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Will definitely reframe from doing it if not necessary. But why did it make lines appear?

Give it time, barely dry. From street, bet you can’t see. go by and take pic tomorrow from bottom of drive.
You’re always going to have lines unless you use a circle method, which is not time effective. It’s the nature of the piece of equipment you’re using. The nozzle passes over the sides a lot more than the front or back of surface cleaner. Basically the lines are cleaner. When you use a heavy post treat, what everyone is really trying to do is bleach out the less clean portions. But if they’d learn what the heck they’re doing wouldn’t need to. That’s the reason I said I nearly always go over twice. Still going to be some difference, but not as much.

If you watched video, you saw how on the verticals along the sides, you ALWAYS make 2 passes, otherwise when you make your turn, or stop to head the other way, you’ll see the difference between the places where you made one pass versus 2 where you made your turn.

Unless you have heavy embedded algae that’s still showing after cleaning, then you can post treat with something stronger than HW mix, though realistically, if you do a good job of cleaning, and post treat with your hw mix, that will generally take care of it in about 5min. If not you can touch up a few spots in less than a min with a pump up.

Next time, show us a before, so we can see what you’re dealing with. The ones you’re cleaning don’t look like they were terribly dirty.

This the crap I deal with regularly - hw pre-treat, 2 passes - hw post treat - Sometimes if really dirty, like below, I’ll hit driveway with hw pre-treat when I first get there, let it sit while I do house, and then hit it again right before I wash it.


Maybe I should’ve been more specific. Why did the post treatment, as pictured, make lines appear that weren’t previously there. Then, why after it was washed away, did it nearly go back to normal? This is what I was asking.
This one was decently dirty but came out good

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With 3%, 90% of it’s work is done inside 10min so you rinsing it off after that probably didn’t have much effect

Always wash with the least pressure possible… I’m big on chems! I let chems do the work… if you know your ratios and give the chems time dwell they will do most of the work for you

Rinsing it did have an effect. It made the lines that had appeared when I applied the post treat disappear. Thats what this is about–my post treat making lines appear when the concrete was spotless before hand. That’s what I’m asking you. Why is SH making lines randomly appear?

learn to do random patterns will make everything look even . you are not mowing a yard. I uses a sweeping type pattern side to side . No strips or lines can be seen. Then rinse with a fan tip off my j=rod . Works like a charm.

We weren’t there, so we don’t know exactly what you did or the time frame. Anytime you re-wet the concrete right after you’ve cleaned it, with anything, you’re going to see the lines for awhile. You’re not making any sense. If you post treated and you saw them, how long did you wait till you rinsed it? Was it totally dry for 30 min or what? It’s good now, so quit worrying about it. Now you know you don’t need to use 3% most the time if you clean it thoroughly. You’ll learn. Every job is different. Once you clean a few hundred, you’ll get a feel for it.

I’ve found that when doing pavement it’s all about the pretreatment. I start by sweeping, and spraying off any loose, debris. Then I spray it down with either standard pavement cleaner( mieric acid), or bleach. The key is to check the activation time on the cleaner and let it soak. Bleach I usually allow at least ten minutes, and spritz during that time so that it doesn’t dry.