# Cleaning Concrete Stains?



## noggin (Oct 4, 2020)

This is a mess my last smoker, an upright, left for me a couple of years ago. I'm not sure if this is grease or rust stains. I think grease would normally be black, so I'm leaning towards this being rust. Any thoughts on cleaning it? I think I'm going to try bleach first, then TSP. I tried a pressure washer with some concrete cleaning additives, but the stain didn't even lighten. I might have actually tried bleach at some point.

I've read that TSP is bad for plants. If I clean this with TSP, should I just saturate my yard around the porch with water both before and after cleaning? I'm sure bleach isn't great for the lawn either, but I suspect it isn't as bad as TSP.


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## Steve H (Oct 4, 2020)

Brush in some simple green. Let it sit for 15 minutes. Then rinse with a pressure washer if you have one.


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## D.W. (Oct 4, 2020)

So I'm reading this post and here is the advertisement at the bottom of the page:








That being said, we would use concentrated Orange at the asphalt plant I worked at in my late teens to clean oil and asphalt. I would try some of that stuff, I think you can get it now at any of the big box hardware stores.  TSP works ok, but typically use that for light cleaning jobs such as walls prior to painting.  I've gotten wallpaper off of walls with TSP, but that's about the toughest it would work on.


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## noggin (Oct 4, 2020)

Simple Green is a no go. Just gave it a shot. Tried one section with some diluted SG and another section with full strength SG. No change in stain level in either location.

D.W. - Do you mean something like this type of cleaner? I didn't see "concentrated orange" except in grocery stores (and I doubt you mean orange juice) and several orange based citrus cleaners. I'll be surprised if this works, but I'll give it a go.


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## agaffer (Oct 4, 2020)

I had to clean rust off my driveway and I just poured a little bleach on the stains, rubbed them with a nylon bristle brush and then let the sun bleach it out. Like you I didn't want the plants to take a beating. Turned out fine, rust is gone. Takes a few weeks before the white bleached out concrete to match the surrounding concrete.


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## flatbroke (Oct 4, 2020)

Did you spray some carb cleaner on it? May work and evaporate fast


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## SmokinAl (Oct 4, 2020)

You may want to try pool acid. I have used it to clean stains in my driveway. Just be careful not to breath the fumes. I usually just use a paint roller & roll it on. Leave it on for a few minutes & rinse it well with plenty of water, cause it will etch the concrete. This is what I would try if nothing else works.
Al


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## SecondHandSmoker (Oct 4, 2020)

You could try some WD-40 too.


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## Winterrider (Oct 4, 2020)

This works great for a lot of different cleanups. Either full or diluted. Brother uses in his mechanical shop all the time.


			Robot or human?


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## chopsaw (Oct 4, 2020)

noggin
 try  wetting the area  . Then sprinkle baking soda on and scrub with a stiff damp brush , then rinse . Might have to repeat a couple times , but this is a safe way to start . 
Go to Lowes or Home depot and get the brush used to clean masonry that screws on to a broom handle .

You can step up to powdered detergent for washing clothes . It has phosphates in it . 

If you decide to buy a commercial cleaner , buy one for the type of surface you have . In your case concrete . Universal cleaner is not the same thing . 
Muriatic acid works , just be careful with fumes and splashing . Not good on plants . 

You say the things you tried didn't touch it . Could be the stain is soaked in deep . Pay attention to the water . If it changes to the color of the stain it's taking some off . Just might take several tries .


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## mike243 (Oct 4, 2020)

Looks like rust to me, some rust buster followed by a soapy scrub?


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## noggin (Oct 4, 2020)

I agree Mike, I'm leaning towards rust on this one. So far, TSP and bleach have done nothing to this stain. CLR seems to have reduced the heaviest spots by a small amount. I'm a bit concerned about using CLR on concrete though. CLR is supposed to remove calcium and lime which I think are common components of concrete.



 chopsaw
 suggested baking soda. Just checked youtube and someone showed using that (and hydrogen peroxide) to clean the concrete around the pool and it worked great. But... it left a HUGE clean spot and doesn't match the rest of his pool surround. I think I'm going to try that next.


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## chopsaw (Oct 4, 2020)

noggin said:


> I think I'm going to try that next.


That suggestion comes with experience . The tuckpointers use a high pressure spray of baking soda to clean exterior of  some of the existing  buildings I've remodeled . 
I would start with water first , then  you can also try vinegar instead of water . 
Yes , it will clean the concrete  around the stain . You can work in a square  , tape off an area . Maybe work to joints in the slab it self . 
Get it cleaned as best you can , then blend it in with a power washer .


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## noggin (Oct 4, 2020)

Baking soda and hydrogen peroxide did discolor a little bit as a I scrubbed. I'm going to return the orange cleaner and carb cleaner as I don't expect either of them to work (they're still unopened) and pick up some more baking soda. I'll also grab something I saw that was made specifically for rust on concrete and give that a shot too.


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## johnmeyer (Oct 4, 2020)

An old trick that works incredibly well on oily stains is to use a torch to burn it off. Like with any cleaning approach, you'll want to test it on a small area first. I can usually reduce the stain by 80% or more.

_[P.S. This is for concrete, not asphalt!]_


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## mike243 (Oct 4, 2020)

Heat will blow the top layer of concrete off unless it was jitter bugged and thats not a common practice on driveways, to high psi with pressure washers will also do it


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## kmmamm (Oct 4, 2020)

If it is a rust stain, no amount of degreaser will cut it.  Try something called ”iron out”...it will take care of the rust.  Be sure to follow safety precautions listed on label.


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## Gecko10 (Oct 4, 2020)

flatbroke said:


> Did you spray some carb cleaner on it? May work and evaporate fast


I have had success using this.


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## bill1 (Oct 4, 2020)

johnmeyer said:


> ...use a torch to burn it off....


The one thing I haven't tried.  Thanks.  
Personally I find solvents, esp Gumout and carb cleaners, pretty ineffective.  What I've been using on motor oil stains is to wet it good with gasoline, followed quickly with a mix of equal parts of dirt and sand.  Grind it in with your heel.  Do a little dance with both feet  if it's a big spot.  Let it set for a day.  Seems to wick up  ~20% of the stain.  Sweep up the mix next day and repeat.  After 10x, you're down to only ~10% of the original ugliness, without affecting the surrounding area.  I doubt anything  works perfectly.  Like a cheap paint job, it looks great at 20' but not so great at 3'.


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## johnmeyer (Oct 4, 2020)

bill1 said:


> The one thing I haven't tried.  Thanks.


I think you'll find it works better than the various solvents. Don't expect to have the stains disappear 100%, but as I said earlier, I usually get an 80% reduction.


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## zwiller (Oct 5, 2020)

I am a handy guy and can fix mostly anything but for some jobs it's best to call a pro.  They have the chems and tools and most important they have experience.  IE I had some really bad carpet at a rental and was ready to pull it but my Mom suggested to at least try a pro first, even though no one in my family had ever hired a carpet cleaner before, we always just rented the machine.  So I do and to all of our surprise, the carpet was basically like new when it was done!   For DIY you are gonna need acid like 

 SmokinAl
 said.  Muriatic/pool, citric, oxalic.  I would then follow up with a base cleaner to neutralize like pool shock/SH injected into a power washer with a surface cleaner attachment.  As already mentioned, you are looking at a reduction at best.


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## Jabiru (Nov 4, 2020)

I have used Kitty litter (the sand) multiple times, leave it on for a few days. Then soak  it  with 1 part chlorine 3 parts water. Keep it wet with that for a few hours. Pressure clean.


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## forktender (Nov 4, 2020)

A torch is not going to do a thing to a rust stain. Wet the surface then sprinkle TSP  powder on it. Let it stay on for a day or two moisten it and scrub with a wire brush. If that don't work try Lime away and a wire brush. Wear rubber gloves and safety glasses.


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## tsapp (Nov 15, 2020)

Try oxalic acid  wet the area sprinkle  a fair amount on work it with a brush a little. let it sit a few minutes and then rinse it off.  Don't let it dry on there better to do it on a cooler or cloudy day.  so you can let it sit longer. You can put a tablespoon or two of this stuff in the back of a toilet and let it sit a while  and then flush and the inside of the tank will look brand new.   also works great to get rust stains out of a dishwasher.


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## bill1 (Nov 15, 2020)

Thanks.  Oxalic acid is good on rust stains.  I'll have to try it for oil and grease stains.


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## jdixon (Oct 5, 2022)

noggin said:


> This is a mess my last smoker, an upright, left for me a couple of years ago. I'm not sure if this is grease or rust stains. I think grease would normally be black, so I'm leaning towards this being rust. Any thoughts on cleaning it? I think I'm going to try bleach first, then TSP. I tried a pressure washer with some concrete cleaning additives, but the stain didn't even lighten. I might have actually tried bleach at some point.
> 
> I've read that TSP is bad for plants. If I clean this with TSP, should I just saturate my yard around the porch with water both before and after cleaning? I'm sure bleach isn't great for the lawn either, but I suspect it isn't as bad as TSP.


I've got a 40x60 that used to be a marijuana grow...they made a real mess of the concrete floor. I'd love to pressure wash the entire thing but I can't get my drywall wet. I've tried mopping with some simple floor cleaner, but I can't really scrub as hard as I need to with the mop. The floor looks like it was sealed, to begin with, but a lot of that has flaked off, even though it's only about 2 years old.

What should I use to clean this floor....without making a huge, wet mess inside?


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## zwiller (Oct 5, 2022)

I'd apply a stripper with pump sprayer, let dwell, and then follow up with PW with surface cleaner attachment.   https://www.restore-a-deck.com/RAD-Stain-Stripper.html


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## bill1 (Oct 5, 2022)

jdixon said:


> I've got a 40x60 that used to be a marijuana grow...they made a real mess of the concrete floor. I'd love to pressure wash the entire thing but I can't get my drywall wet. I've tried mopping with some simple floor cleaner, but I can't really scrub as hard as I need to with the mop. The floor looks like it was sealed, to begin with, but a lot of that has flaked off, even though it's only about 2 years old.
> 
> What should I use to clean this floor....without making a huge, wet mess inside?


Maybe just paint it?  (Sealing is cheaper, but if it had a prior coating that's flaking off, I don't think that wil work.)  
Are you worried about odors or just looks?


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## chp (Oct 6, 2022)

So from the chemistry side, rust is an oxidized metal, to get the oxide broken up again, a reducing agent will do the trick. Formic acid, oxalic acid, sulfites are examples of a reducing agent. Just check the label on the rust removers. The challenge is that there is likely other things in the concrete that will also react.

 Changing the pH with acids and bases can also put the oxide in solution and allow you to remove it, but it does the same thing with your concrete. So, you can try laying a rag over the stain and soaking the rag with the reducer or acid/base to increase the contact time, then after the rag starts to dry, remove it, pour on some kitty litter, grind that in to absorb everything, sweep it up …and repeat, just do some small test runs to see how it affects your concrete.


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## bill1 (Oct 7, 2022)

Guess I haven't grown enough pot...what do we think has stained the concrete?  Chlorophyll?  Drained steer manure?  
If you've only tried a mop so far, consider renting a commercial carpet cleaner that has a large round (18"?) rotating bristle brush.  They can do a lot of scrubbing with a minimum of water since you're worried about splashing on the inside walls.


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## boykjo (Oct 7, 2022)

I dont recommend heating concrete with a torch. If it has moisture in It, it can explode.


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## mike243 (Oct 8, 2022)

grind the surface, the stain is embedded into it, a hand grinder if a small spot or a stand up model if a large area. after clearing it out clean and seal with a quality sealer to help prevent this


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## jdixon (Oct 18, 2022)

chp said:


> So from the chemistry side, rust is an oxidized metal, to get the oxide broken up again, a reducing agent will do the trick. Formic acid, oxalic acid, sulfites are examples of a reducing agent. Just check the label on the rust removers. The challenge is that there is likely other things in the concrete that will also react.
> 
> Changing the pH with acids and bases can also put the oxide in solution and allow you to remove it, but it does the same thing with your concrete. So, you can try laying a rag over the stain and soaking the rag with the reducer or acid/base to increase the contact time, then after the rag starts to dry, remove it, pour on some kitty litter garage flooring las vegas, grind that in to absorb everything, sweep it up …and repeat, just do some small test runs to see how it affects your concrete.


thank you so much for your suggestion


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## jdixon (Nov 7, 2022)

chp said:


> So from the chemistry side, rust is an oxidized metal, to get the oxide broken up again, a reducing agent will do the trick. Formic acid, oxalic acid, sulfites are examples of a reducing agent. Just check the label on the rust removers. The challenge is that there is likely other things in the concrete that will also react.
> 
> Changing the pH with acids and bases can also put the oxide in solution and allow you to remove it, but it does the same thing with your concrete. So, you can try laying a rag over the stain and soaking the rag with the reducer or acid/base to increase the contact time, then after the rag starts to dry, remove it, pour on some kitty litter, grind that in to absorb everything, sweep it up …and repeat, just do some small test runs to see how it affects your concrete staining jacksonville.


thank you so much for your suggestion


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