Cleaning marble slab walkway

Ruthanne Brann
by Ruthanne Brann
I have pieces of marble that I use for a walkway outside. They have green and dark blackish areas from being under decaying leaves for a couple of years. I tried muriatic acid diluted with water, but it did little - I used a broom as I didn't want to get too close. Can anyone help me? At this point, I am not too concerned about damaging them as they are already damaged.
cleaning marble slab walkway, These pieces are supposed to be basically white
These pieces are supposed to be basically white.
cleaning marble slab walkway, These are supposed to be white or pink
These are supposed to be white or pink.
  13 answers
  • Janet Pizaro Janet Pizaro on Sep 07, 2016
    Try a product called Wet and Forget available at Home Depot in the paint department.
  • FRED RIGGS FRED RIGGS on Sep 07, 2016
    I would use a pressure washer. I use it on our regular sidewalk, and makes them look new and fresh, compared to the other homes. Wet and Forget might help, but follow it with a good pressure washing. Use one with 2100 psi. Muratic acid just disolved part of the surface. Wrong thing to use IMO
  • Cindy Hagemann Cindy Hagemann on Sep 07, 2016
    I agree with Fred - use a pressure washer - they will be clean in a jiffy!
  • Sam Sam on Sep 07, 2016
    A pressure washer will get it all out. You won't even need any soap/detergent.
  • Dale Barnes Dale Barnes on Sep 07, 2016
    Plain Old Hydrogen Peroxide. You can purchase by the gallons. I tried pressure washing, Wet and Forget, White vinegar and bleach. Hydrogen Peroxide was the only thing that got mine completely clean.
    • Ruthanne Brann Ruthanne Brann on Sep 07, 2016
      Thank you. I'm not sure about the power washer because it will greatly disturb the stone dust around the marble. I would like to try your suggestion. Was it actually marble that you used it on? And where should I look to find gallons?
  • FRED RIGGS FRED RIGGS on Sep 07, 2016
    Bleach is dangerous, You can put the pressure washer on needle spray so you do not disturb the stone dust. Ask your pharmacist to order H202 for you in gallons. Oh, that is peroxide. Wear old clothes, peroxide is a bleach, like you brush with sometimes, clean wounds with it also. Don't leave the cap off. Oxygen and light will deteriorate it.
  • Dale Barnes Dale Barnes on Sep 07, 2016
    Yes, I cleaned Marble and also Saltillo Tile with Hydrogen Peroxide and Saltillo is so porous that the mildew really gets in there. I used a garden sprayer full of straight hydrogen peroxide and sprayed it on and wet it thoroughly. Then I let it sit for about 20 minutes while it bubbled up. I was doing a very large patio area so I then took a push broom and was able to get most of it up on the first try. It was gross. There were a couple of particularly bad areas I had to spray again but your marble is not nearly as bad as was mine. Hydrogen Peroxide is a natural product and also does not hurt the environment. Just google Where can I purchase hydrogen Peroxide by the gallon and numerous places will come up. That is what I did. Good luck.
  • Phil a Phil a on Sep 07, 2016
    Marble, like most natural stone, is permeable, meaning it will pass water/moisture through. That is why it, and other stone surfaces, have to be sealed when used for counter tops, so oil and water stains won't form. It looks like your stones are laid in dirt. That might be the cause, allowing moisture, with the dissolved minerals and salts from the dirt, to wick from the bottom to the top. If not sealed, stone, especially white stone like marble, should be laid in a gravel or sand bed, not dirt. I have a feeling the stones are stained from underneath and no amount of surface cleaning will get rid of it. Let us know what you find out. Phil
    • See 2 previous
    • Ruthanne Brann Ruthanne Brann on Sep 08, 2016
      The stone dust is also under the stones and does drain. Hadn't noticed that white circle and don't know what made it, but I will think on it. I did try muriatic acid, but I probably diluted it too much. It was advised against, but I figured I didn't have much to lose.
  • Inetia Inetia on Sep 08, 2016
    There's always spray paint.
  • Bon7229865 Bon7229865 on Sep 08, 2016
    Try the product "Spray and Forget". It doesn't work immediately but over time the black will be gone and the producthelps keep the stone clean for a while. Find it in the paint Dept of home depot.
  • I would use bleach water and a stiff brush. Since these are outside I don't see any real harm from using the bleach. A 2 parts water to 1 part bleach should work fine. The bleach will kill any bacteria that is growing on and dis coloring the stone. If you need something that has some grit to it, make a paste out of baking soda and water and, using a stiff or wire brush, just work it over the stone and rinse. Good luck!
    • Ruthanne Brann Ruthanne Brann on Sep 08, 2016
      I think I will try this as the other suggestions, although helpful involve more expense.
  • Ruthanne Brann Ruthanne Brann on Sep 16, 2016
    Thanks for all the suggestions. I used my already diluted muriatic acid without wetting the marble first and it worked better. Then I tried Comet with bleach and a hand brush and that worked even better. Finally I went to town (literally) and bought a gallon of bleach, a sponge mop at the Dollar Tree Store and a deck scrubbing brush/broom with a long handle at Kmart. I applied the bleach directly with the cheap sponge mop and then gave it a little scrub with the deck scrub 'broom.' I let it sit a little while and then rinsed it off. So, it ended up that in consideration of expense, exertion, and the imperfect condition of the marble to begin with that plain old bleach was the best for me.
  • Amazing Amazing on Mar 27, 2021