I cleaned the concrete balcony when it was raining, just poured some water on it and went at it with a brush, I wouldn't even say I used a lot of water. Now there's quite heavy staining, especially where there are cracks, and they don't seem to have improved. Most of the floor dried up fairly quickly but it has looked like this since 3 days now.

Any ideas what I should do, just wait?enter image description here

  • 1
    What was on the balcony before the rain started that prompted this cleaning? It's entirely possible that you simply moved the dirt that had settled into the cracks onto the surface.
    – FreeMan
    Commented Jul 14, 2023 at 15:49
  • I had been trying to remove some stains before by putting some bicarbonate on them (not seen in picture), but one can be seen upper right as very dark patches. So I scrubbed away the bicarbonate and tried to push it to the drain pipe. So yes maybe, still feels a bit strange though. And the patches did not go away anyway with the bicarbonate
    – KOT
    Commented Jul 14, 2023 at 16:24
  • The density of the concrete is not uniform, there is nothing you can do about it. I will wait for the floor completely dry and apply a protective/non-slip coating.
    – r13
    Commented Jul 14, 2023 at 16:57
  • @r13 do you think it will dry up eventually?
    – KOT
    Commented Jul 14, 2023 at 17:09
  • 1
    Yes, it will take time for water in the softened areas. You may try to find and use water-based protective material or something that is applicable to moist but dry surfaces (if it is not wet by touch).
    – r13
    Commented Jul 14, 2023 at 19:23

1 Answer 1


The concrete is porous and will suck up water and anything that is in the water.

You should consider something to seal and cover the surface.

Tile, epoxy coating, even a concrete stain or paint. You will continue to have the uneven look you are fighting and dislike unless you get the floor sealed somehow. As a bonus keeping water from seeping into it will help the structure.

  • Thanks for the answer. So it might be minerals that got stuck in it? I guess that's difficult to get out? It's not like the surface was swimming in water and I used a water scraper to get rid of the worst. The area where the extration pipe is looks better and it had the most water for the longest time. But I guess I need to let it dry completely before I do anything? This surface doesn't get a lot of water on it usually because there is a roof
    – KOT
    Commented Jul 14, 2023 at 19:46
  • The bottom line is that if you don't want the surface to have a "marbled" look, you need to coat it with something.
    – RMDman
    Commented Jul 14, 2023 at 21:42
  • OK, I can do that. Question I guess is if I can reverse the damage already done now?
    – KOT
    Commented Jul 14, 2023 at 22:53
  • probably not...it is not on the surface it is in the concrete.
    – RMDman
    Commented Jul 14, 2023 at 23:07

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