This stair handle wall is concrete, and it has been finished with white putty and paint.

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I don't know what's this grey color stuff and any ideas to fix this would be great.

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  • And judging by the sky and the water on the railing it's outside and gets rained on.
    – Ecnerwal
    Commented Nov 26, 2023 at 14:23

1 Answer 1


Dirt, mold, mildew and/or algae.

Wash it, bleach it, possibly pressure-wash it with likely paint removal as a result.

Repaint it once dry with suitable masonry primer and paint for exterior use.

  • Thanks , I will try with Bleaching and see how it goes
    – Vivo
    Commented Nov 26, 2023 at 14:59

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