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Removing efforescence stains from wall

Discussion in 'Building' started by SonicBoom, 20 Jun 2021.

  1. SonicBoom

    SonicBoom

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    Hi there

    I had a line of triangular bricks built on top of my wall and it looks great but I’ve got that efforescent white stuff that has run all down the wall.

    I’ve watched a couple of youtube videos and bought some ever build 401 high strength brick & patio cleaner. Followed the instructions, to the letter, wet the wall down, then applied the cleaner into the brick work, waited 20 minutes, went out and scrubbed the wall.....really gave it some elbow grease....and it wasn’t coming off (well barely).

    Any ideas? Ive just been out there, did this in the morning, its now evening, still doesnt look like its been touched. Should I just give it some more treatments? Is there anything else I can try? The cleaner contains hydrochloric acid <10% w/w

    Sonic
     
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  3. JohnD

    JohnD

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    how long ago was the brickwork done?

    post some pics

    leave it alone and it will weather off, unless there is a leak making it wet.
     
  4. foxhole

    foxhole

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    As John said no need to touch it, the salts will wash away in the rain .
     
  5. ^woody^

    ^woody^

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    And come back in the dry. :cautious:
     
  6. ^woody^

    ^woody^

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    Efflorescence won't wash off, it just gets reabsorbed into the wall when wet, and returns when the moisture evaporates.

    True it needs to weather off, but you might be dead before it does.

    Dry brushing may help.
     
  7. johnny2007

    johnny2007

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    So question comes naturally: how do you prevent it in the first place?
    It's never happened to me, so is it a matter of luck?
    Sand, cement and plasticiser, what makes the effluorescence and how to prevent it?
     
  8. JohnD

    JohnD

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    it's mineral salts. Water in the bricks moves to the surface where it evaporates and leaves the dissolved minerals behind. Where I live the water is very hard so you get powdery bloom of lime from the mix as it dries out the first spring after the build. It usually weathers away, but below dpc where groundwater is evaporating off the bricks you can get quite a crust on the first and sometimes second course.

    the sand may also contain other minerals, which could be anything. They may come out more if the wall is thoroughly wetted by a leak. if it is just surface damp from rain that quickly dries out, it soon stabilises. You can see really bad deposits on neglected surfaces like old railway bridges where water has been migrating through the wall, especially if there is a drainage fault.

    Washing it off with water does not help. If it dissolves surface crystals they can soak back into the brick; and making the brick wet causes more minerals to dissolve in the interior, and they will subsequently migrate to the surface and cause more efflorecence.

    Dry brushing will take powdery crystals off the surface. A wire brush or a scraper will damage the bricks.

    in some cases, like conversions of old cowsheds or stables, there may be a century's urine soaked into the walls, containing nitrates and other chemicals.

    if you don't get it, maybe you live in an area where the sand is cleaned by fresh water, and the water is not hard.
     
  9. ^woody^

    ^woody^

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    It's a phenomenon. It may or may not happen.

    It's soluble salts in the clay or the sand, and can take a specific set of circumstances to come into play, so that's why walls that have been up for years can suddenly develop it.

    One thing to almost guarantee it to occur is to allow bricks to be saturated before laying, and to allow part built walls to get soaked from the top before being finished.

    Likewise, specific seasonal damp and drying cycles can have a part.
     
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  11. SonicBoom

    SonicBoom

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    Interesting to read the thread, I had the work done about a year ago. I’m having my house valued in a couple of weeks although I’m not definitely looking at moving but what with first impressions counting and everything, it looks really messy. I was thinking I could paint the wall white, not really what I wanted to do but the house is pebble dash white so they would match, or it might look a bit overkill.
     
  12. SonicBoom

    SonicBoom

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    Also I was thinking if I used up the acid treatment every couple of days, could that help?
     
  13. SonicBoom

    SonicBoom

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    Here is a pic of the offender
     
  14. JohnD

    JohnD

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    where?
     
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  15. SonicBoom

    SonicBoom

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    28C8DDB7-4B86-4E0E-982B-99CA0A8CEC2B.jpeg
     

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  16. SonicBoom

    SonicBoom

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    Sorry about that! There you go
     
  17. johnny2007

    johnny2007

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    You sure the milkman hasn't got anything to do with this?
     
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