Cleaning Flagstone

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  • Greg in Maryland
    Established Member
    • Nov 2006
    • 250
    • Montgomery Village, Maryland
    • BT3100

    Cleaning Flagstone


    I need to clean the hearthstone in front of my fireplace. I put a potted plant on it last winter and it left stains on the stone. In addition, I have what looks like rust stains on the stone.

    I believe that the stone is flagstone or blue stone. The stone is similar to this:

    I have tried soap and water with a sponge/scrub pad, but it didn't do a thing. I was thinking of using TSP (Tri-Sodium Phosphate) with a bristle brush. Does anyone see any downside to TSP on stone? Any better alternatives?

    I am aware of the caustic nature of TSP and the need for safety precautions, so that isn't a big issue.


  • LYU370
    Established Member
    • Mar 2005
    • 215
    • Streamwood, IL.

    Here's a site with a bunch of good info, a lot of it refers to their products, but it sounds like you can use a grout cleaner to get rid of the stains.



    • christiandad
      Handtools only
      • Sep 2022
      • 1

      My go to man when in need of inspiration and tips is Devin, I highly recommend you check some tips here. Hope it helps!

      how to build a flagstone patio. For the past 10 years I've provided DIY phone consultation services teaching flagstone walls masonry and hardscaping


      • capncarl
        Veteran Member
        • Jan 2007
        • 3567
        • Leesburg Georgia USA
        • SawStop CTS

        I would fear that anything you put on the stone to remove rust will leave a light spot causing you to have to put it pop they whole fireplace.


        • anglinastone
          Forum Newbie
          • Sep 2022
          • 7
          • United States

          In my opinion, Cover your flagstone patio with white vinegar. Allow the vinegar to sit on the flagstones for a couple of minutes. Rinse the vinegar from your flagstone patio. Use your scrub brush to clean your flagstone patio​