Driveway cleaning

Can anyone give me advise on the best way to remove the real dark spots on driveways that remain after using a surface cleaner? I’m using 3600 psi at 8 gpm and hot water. The driveway cleans up great except all the real dark spots that i have to go over and over when rinsing. Do you suggest I put down a type of pre spray on it before cleaning, and if so, what would be best to eat that stuff up! I did a driveway today that should have taken me an hour but it took 3 hours instead removing the spots.


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I use a pump up sprayer from Home Depot with 70% sh and 30% water. That will get 99% of those left over stubborn stains.

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Do you guys charge extra for stubborn stain removal?

That sounds like it would evaporate pretty quickly after spraying it down? I don’t know if it’s mold or just bad dirt spots. Some come off pretty easy using the gun
but not the surface cleaner. Some I have to get right on real heavy and hard just to get it to come off.

Here is a before and after of the back patio. It came out nice but boy it took a good while to get done!

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Sorry! Here is the before


Hit with hw mix after cleaning and walk away

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^ What he said. ^

That’s not a wash, that’s a restoration. It hasn’t been touched in years. The more often they have it washed, the cleaner it will come.

After looking at the pic definitely a restoration. Offer sealing of the concrete to maintain color. Pretty easy up sell when the owner sees results. I like to keep a pic on file to show how nasty surface was before

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Looking at your pictures. I would agree with the restoration. When you quote something like that I would give the customer options. Some only want it washed, others want it restored. Set expectations with the customer. If they only want a wash that is what they get regardless of how clean it gets.

You can’t invest too much time on it or you lose money. They get what they pay for and most will be thrilled if you set the right expectations.

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Are you pre treating concrete like this? We put down a strong mix to loosen up the mold, surface clean and then spray down mix to leave…sometime you do get the spots that have to be wanded off but most will disappear with the after treatment

I come across that every single day. I was stumped at first too. My method is downstreaming with straight SH with a high draw injector(after pretreatment with HW mix and cleaning) as long as you get the top layer off with the surface cleaner, the spots will just disappear after about five minutes. If they don’t disappear hit it again. I used to obsess about them, now I just do sections a a time, rinse apply post treatment, move on and when I’m done the spots are gone. That little patio should take 25 minutes with dwell time.

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Oh and make sure our SH is fresh. That could be a problem too.

Good Tips!


Wow! That is some bad stuff!

When you say you downstream the SH does that mean you run it through the surface cleaner or spray it on using the wand? Another dumb question, what is HW?

You spray it on using a wand or a ball valve. Never run any chemical through your surface cleaner. HW stands for house wash mix. Standard mix you use.