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Concrete stains that won’t budge

dot1 | Posted in General Questions on

So I’ve tried dish soap and scrubbing.  Oxygen bleach and scrubbing.  Regular bleach.  White vinegar.  Power washing.  All that happens is the area around the brown stains gets lighter making the stains seem even worse.  Is there anything that has been proven to work and won’t poison the entire area around the cement?  I was going to try those enzymatic concrete cleaners, but labels say they are for petroleum stains.  These are not that.  Is painting the only option?  Or having it broken out and re-poured?  Could it be sanded?  I would brick face over it, but I already have brick on the house in that area, and that’s just too much brick.  Thanks in advance for any suggestions.  Not sure what caused these stains.  Shouldn’t be mildew — nothing leaking in that area.  There was some mossy-algae type stuff in another area from a gutter leak, but that just power washed away.

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  1. Expert Member
    BILL WICHERS | | #1

    Muriatic acid is often used to clean concrete, but even that won't always get a deep stain out. You can grind concrete, and you can usualy rent the equipment to do it. Grinding takes a bit of skill, but it's not terribly difficult to do. Grinding will actually remove small amounts of the surface of the concrete, so you can get any stain out -- but you might need to make several passes.

    I can tell you that that column will be in the way of the floor grinders, so you'll probably have to use a diamond cup type grinding wheel on an angle grinder. You have to be careful not to gouge the concrete when using these.


    1. dot1 | | #2

      Thanks, Bill. Now I have to figure out which I would be less afraid to use - - an angle grinder or muriatic acid.

  2. plumb_bob | | #3

    Concrete is very porous so whatever the stain is it may run quite deep, and you may not be able to get it out.

    Have you thought about acid staining the entire area? With the right choice of colour/tone the existing stain could probably be hidden.

    I assume you are a very detail oriented person, because if it was my house I would just let it be, it does not look too bad.

    1. dot1 | | #4

      Thank you for saying it doesn't look that bad! There used to be a television commercial where a guy in a job interview had a stain on his tie, and the interviewer couldn't hear him over the stain. That's what the concrete stain is like to me. I'm not a huge fan of the acid-staining look, but if it would make the stain disappear I would do it. The problem is that my brick is very loud, and it kind of needs the plain cement to calm it down a little. Maybe I should paint over the stain AND the brick! Here's a picture of my brick (it needs a whole separate post). At least the brick distracts from the stain.

  3. plumb_bob | | #5

    I could happily live in a cave so maybe not the best guy to ask about minor aesthetics!

    Good luck

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