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Thread: removing iron stains from concrete garage floor?

  1. #1
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    removing iron stains from concrete garage floor?

    Poked around in the old threads a bit, most of those are about petroleum staining.

    What I have is a 40 years old house. We have lots and lots of iron in our water. Under the water heater and boiler we have brown stains on the slab garage floor, 40 years worth.

    Water heater and boiler are getting replaced next week. The plan is our boiler guy is going to take the old boiler and old water heater out on Day One. Then he will come up with a plan and go shopping for valves and expansion tanks and so on. Boiler guy returns on Day Two @ 0800 to reassemble the new components. We will be without domestic hot water for one night.

    I have from about 1400 on Day One to 0800 on Day Two to get into that corner of the garage.

    Chores I would like to get done:
    Priority one:
    scrape texture from ceiling, prime and paint.
    clean copper piping of accumulated grime.
    clean wiring of accumulated grime
    clean walls of accumulated grime
    prime and paint walls
    replace 120vac three receptacles and one switch
    replace dryer vent pipe - runs behind the water heater in the corner.

    Priority two
    Do 'something' about the brown iron staining on the concrete floor in that corner of the garage
    Inspect legacy circuit for electric water heater original to house.

    I am not going to try to make a silk purse out of a sow's ear. This is a 40 year old suburban house, not economical to turn it into a new build McMansion. My thinking is if I get the visible stuff, eye level and up, looking good; then having legacy stains on the floor shouldn't be a problem. We are planning on a square of closed cell foam on the floor or a water heater stand to defeat thermal bridging, then a catch pan on that for the water heater to sit in and on.

    **Is there a simple and fast way to maybe clean that corner of the floor without going bananas on stain removal with time I don't really have?**

    Thanks

    FWIW the garage slab is cool enough in the winter that I just set my incoming beer on the floor to cool it down to consuming temperature. Water will continue to be heated by a loop in the boiler, the water heater is just a storage tank.

  2. #2
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    Why not just paint the floor too?
    Hobbyist

  3. #3
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    Quote Originally Posted by Stan Calow View Post
    Why not just paint the floor too?
    That would be an option if someone knows of a good floor paint that can stick to iron staining. The wife and I talked about taping off a rectangle under the new boiler and water heater and just painting that section.

    I personally don't know of a floor paint that doesn't eventually crack and peel. But I do have a free 220 breaker now. I have been doing what I can to lighten my workload for the overnight marathon and now have the option for a 3-5 hp dust collector.

  4. #4
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    Well I've used porch and garage floor paint outside, successfully. And they do make a concrete "stain" (Home Depot) that I haven't used. Yeah they don't last forever, but long enough. I dont know about coverage of the iron stain. I might try a little CLR to see if that helps, but its hard to see anything taking that iron stain down to a bare concrete look. Its still early, so maybe some more experienced folks will chime in.
    Hobbyist

  5. #5
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    Most coatings that go over concrete require de-greasing and etching for a good bond. Industrial coatings for garages are the thing now, might want to check the prep sheet for those.

  6. #6
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    White Vinegar is a mild acid that will remove iron staining. Clean the floor to remove all grease and dirt, then liberally apply the viengar and let it soak at least 10-15 minutes then rinse off. Repeat as needed. If the rust has penetrated the vinegar may not remove all the sstaining.
    Lee Schierer
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  7. #7
    get some of this from Home Depot, it's basically a 'safer' version of 32% muriatic acid--
    30vin.jpg
    and pick up a respirator mask, the fumes can be no fun! And lots of water to rinse...

    You'll likely find it works well when mixed 50/50 with water...
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  8. #8
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    I will plan to try soap and water followed by vinegar and more rinsing as it isn't terribly time consuming. Thanks for the inputs.

  9. #9
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    Check your local hardware store, lots of rust stain removers. But if it has really soaked in, you may be out of luck. Worth a try though.
    NOW you tell me...

  10. #10
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    Oxalic acid is often used to remove rust. It's available as a white powder. If that doesn't work you could use something stronger like Muriatic acid but that will etch the concrete and require painting to look decent.

  11. #11
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    I used C-L-R to remove what I believe were iron rust stains on the basement floor of our previous home. I'm not sure what they were from - they were there when we moved in. As I recall, I had to let it sit for an hour or two, but good results.

  12. #12
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    Vinegar is acetic acid. I use it to remove hard water deposits. Muriatic acid is another name for hydrochloric acid. Both can be purchased in various concentrations.
    Ken

  13. #13
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    I used CLR when my snow thrower left rust stains on my concrete

  14. #14
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    I tried the vinegar. Once the old gear was out, I mopped with Dawn dish soap and rinsed well. The I used about a pint (area is roughly 2x4 feet) of 9% vinegar from the Russian section of an ethnic food aisle.

    I let the 9% vinegar soak for 17.5 measured minutes - most of the internet advice I found said soak for 15-20 minutes- and it was pretty much job done. I got in there with a wire bristled brush and all but a couple particularly stubborn carbuncles were gone, as well as most of the remaining floor paint.

    Then I used 6% "cleaning" vinegar (available from both Home Depot and Kroger here) for another 17.5 measured minutes and that wasn't worth a hoot. I am pretty sure 6% cleaning vinegar has about 20 times the acid power of regular 5% white vinegar like you might use in BBQ sauce or cole slaw. Don't take my word for it. I failed organic chemistry the same semester as I failed calculus 2, back when I think Reagan might have been in the White House.

    At this point I have brown concrete under the boiler and HWW, with a few (three) small bumps of iron deposits, job done.
    Attached Images Attached Images

  15. #15
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    I have a rotary surface cleaner attachment for my pressure washer that works very well for cleaning concrete. You can use muratic acid on any real tough spots. I would imagine you can rent a surface cleaner although o have never looked into that.

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