Understanding surface cleaners

I’ve been trying to have a better understanding of different nozzle sizes and how they affect my desired psi output but am at a loss for words now.

The picture below is a driveway I did and came out striped…and now from my understanding maybe etched? This is after I applied a pre treatment at 1% and followed with a post treatment using a pump up at 5%. I use a 4/4200 machine with a BE whirlaway 16 inch SC. I have 25025 nozzles on it which from the nozzle chart should be me at 2 GPM and 2500 psi at each nozzle on my bar. How is it I’m possibly etching concrete at 2500 psi? Would moving to 25030 tips fix this? Or would changing my spray pattern to 40025 tips also help? Pictures below

Did you use a gauge to determine pressure? Before nozzles and after nozzles? Look I’ve made mistakes, so I am no one to tell you what to do, but I can tell you what not to do. Don’t take a manufacturers word for their pressure, and don’t take a salesmans word for pressure or nozzles. Figure it out on your machine for yourself.

There is a difference between 4 nozzles and 2 nozzles, I didn’t see how many you have.

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I have a 2 nozzle SC and from everything I gather on here pressure gauges are worthless. Thanks for the response…I’m not going off of what the mfr is saying about pressure ratings but I’m using the nozzle chart. So I’m trying to understand how I’m etching concrete when I’m supposedly using the correct nozzle tips (25025’s). Those tips should put me at 2500 psi which shouldn’t etch concrete. The concrete is 10 years plus old

@Racer
you mentioned in a prior post about using 25030’s nozzles. Would this be a solution possibly?

I’m not so sure it’s etched but just where the nozzles cleaned twice. Spray some straight SH in a small area and see what happens. Soak it good. It can sometimes be hard to get enough down when using a pump up.

Thanks @marinegrunt! I read through a lot of your old posts as well around this topic. Does my nozzle size seem correct? Moving to 25030’s should lower pressure more. Would that be a possible solution if it is being etched?

I plan to head back there and apply straight 12% and see if this helps

How old is the concrete? New concrete can be softer and etch with less pressure. Not saying it’s etched just that new concrete could contribute to issues.

10 years plus.

And I thought Marines were the crayon eaters. :grin:

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2500 psi should be fine for most concrete. Are you running through a long length of hose? That will lower the pressure a little more.

Some concrete is just prone to etching and there’s nothing you can do to prevent it. There can definitely be poor concrete pours. Sometimes it’s best to run one strip with the surface cleaner, let it dry, and look at the results.

In your situation I just don’t think the concrete is clean all the way. The lighter areas are where you overlapped your surface cleaner so it got a double pass. @dcbrock had major issues with striping until he upgraded to a 4 nozzle surface cleaner paired with an 8 gpm machine.

You tagged Racer so let him chime in. He’s way more experienced than I am. @MuscleMyHustle can verify too.

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Thanks @marinegrunt. I appreciate you taking the time to respond and help.

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Is the concrete still wet in the pic, can’t tell? How many feet of hose are you running? On my 4gpm machine with 200’ of hose I found the 2503 worked better. 3% on post treatment should be plenty, but need to apply pretty liberally. Go back and look at now if it was still wet. May be fine now.

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Get yourself an x-jet. It makes pre and post-treating so much quick and more effective.
I’ve done the pump up route…it takes forever, and you just don’t quite get the saturation you need.

I’ve been using a 4/4 w/ 16" surface cleaner this whole summer. Most of the time I’m using 250ft with 25025. The last couple driveways I did I used 125ft with 25025. It was a noticeable difference and I prefer it much better.

I have found that in order to not leave striping w/ my 4/4 (and many times I’m sealing the driveway after I clean it so post-treating isn’t an option), I’m having to go in more of a circular pattern like you would with a buffer on carpet. Is it fast? Nope. A 4/4 will never be fast with concrete. lol. But is it efficient, gets the driveway clean, and no stripes are left? Yep.

All that said, the time alone that the 5.5s and 8s talk about saving, make upgrading a no brainer. I’m upgrading very soon.

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@Racer
It was a day later so it was dry. Using 150ft of hose. Guess I will be needing an x jet to get a more saturated post treatment. The pump up was more of just a fine misting so maybe that is part of the problem

1% pre treat is weak.

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You’ll love the xjet. It’ll cover a driveway in 1/20th of the time it takes with a pump up.

Of course, if you can go the 12v route that’s even better.

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I’m not sure it’s etched either I just think you haven’t put enough pre treatment on, problem with a pump up sprayer is it doesn’t put out enough volume to saturate an area that big. SH works while it’s wet it’s probably flashed dried before it had had a chance to work. As far as the pressure goes 2500 is plenty for residential. There is virtually no way of knowing if you will etch 10 year old concrete until you’ve etched it, if that is etched with 2500 psi and it’s 10 years old I would be surprised, at that point there’s nothing you can or could have done.

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See at the 22 second mark where I flash back to part I’ve already done and see how liberal it is and that had been a few minutes by then

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Thanks Rick for sharing that, much appreciated. I think I will need to be more liberal with a post treat. I don’t have a 12v yet so I may need to get an x jet for the time being. How much time are you spending soaking the grass to prevent any damage from a post treatment?

This. Even my spiffy 4 nozzle and 8gpm will stripe so I use a push/pull method someone on here suggested. It’s slower but I don’t have to worry about going back over it again. And no, post treating doesn’t always get it.

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@dcbrock, I’m convinced you’ll bump up to using heat at some point just so you can try to avoid striping. :joy:
I feel like you’ve upgraded just about everything else to try and avoid it!

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