Damp spots coming through lots of stainblock!

Discussion in 'Painters' Talk' started by phoebe goldup, Apr 29, 2021.

  1. phoebe goldup

    phoebe goldup Member

    Evening painters, sorry to return with more problems buuut....
    I have a client who's neighbours roof had caused a leak into their attic bedroom. The neighbour fixed the problem and the area of damp stopped growing. 4 months + later I arrive to redecorate the patch of wall, scrape off the loose material, sand it back, clean it, and apply 1 layer of zinsser BIN, then I fill areas and follow with another layer of BIN, then I cover with 2 coats of the emulsion paint and a stain comes through, so I apply another layer of BIN and another layer of emulsion but the problem is the same. (so far, 3 BIN layers and 3 emulsion layers). I return a few days later and apply an oil based undercoat to the area. When this coat dries you cannot see a stain, so I again apply a coat of emulsion over the top, only to find the same marks coming through again. I'm pulling my hair out at this point. The marks coming through look like darker flecks of wetness, like sweat coming through a t shirt. The house is old, probably 300 years+. Anyone have any idea what the problem could be and the solution??
    Best wishes
    Thanks in advance
     
  2. phoebe goldup

    phoebe goldup Member

  3. phoebe goldup

    phoebe goldup Member

    @oranyoneelsewhocanhelpbutidontknowyournameyet???
     
  4. CGN

    CGN Screwfix Select

    photo may help. Is it a stain, or the whole ‘repair’ that’s showing through?
     
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  5. phoebe goldup

    phoebe goldup Member

    Thank you CGN. It is not the stain block showing through, or the filler, I will get a photo tomorrow if I can get in there tomorrow . Its just random spots that look like moisture but feel dry scattered over the coating
     
  6. CGN

    CGN Screwfix Select

    Ok. Sounds very frustrating. You may have to ‘seal’ the whole ceiling. Nicotine perhaps?
     
  7. phoebe goldup

    phoebe goldup Member

    thank you, it is, Its a wall. I can only think this must be related to the water leak as thats the area Im repairing
     
  8. CGN

    CGN Screwfix Select

    oh ok, didn’t read carefully enough. Wall could still be damp, or penetrating damp from outside etc. Tbh, I don’t think you’ll solve the issue any time soon with paint products etc due to the age and likely construction of the property. You may have to leave for much longer before you can sort this.
     
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  9. Astramax

    Astramax Super Member

    BIN is not the best for blocking damp stains...Cover Stain does a far better job. Will wait to see the photos.;)
     
    phoebe goldup likes this.
  10. phoebe goldup

    phoebe goldup Member

    Yes you're probably right CGN!
     
  11. phoebe goldup

    phoebe goldup Member

    So I called Zinsser after searching some other chats on similar subject and saw you recommend Cover Stain and they said that BINs the one and they cant see what coverstain could add over the BIN, will share pics asap. Thanks @Astramax
     
  12. Astramax

    Astramax Super Member

    They best update their own brochures in that case. :oops:
    Trust me Cover Stain is better over dried damp stains.:)
     
    Last edited: Apr 29, 2021
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  13. Astramax

    Astramax Super Member

    Cover Stain flows out far better than BIN on flat surfaces, remember Zinsser Technical is just that, the real technical department is the end user!
     
  14. phoebe goldup

    phoebe goldup Member

    What do you recommend on what could be a still-damp stain?
     
  15. phoebe goldup

    phoebe goldup Member

    What does "flow out" mean?
     
  16. Astramax

    Astramax Super Member

    Find the source of the damp and cure it.
     
  17. Astramax

    Astramax Super Member

    BIN dries to quickly and can leave a noticeable slightly raised edge you can brush out the edges of Cover Stain as the paint flows better as not so rapid drying. CS dries reasonably quickly but not as quick as BIN.
     
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  18. Astramax

    Astramax Super Member

    @phoebe goldup both BIN and Cover Stain have excellent ratings for use over water and nicotine stains, have used both in fire damaged properties, it is a question as much as what works for you in any particular application.
     
    phoebe goldup likes this.
  19. phoebe goldup

    phoebe goldup Member

    Oh OK I see, they're approximately as good as one another for blocking stains but the Coverstain is better to apply.
    Thank you, I appreciate your help
     

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