Sealing masonry before painting.

Discussion in 'Painters' Talk' started by gingertimmins, Feb 21, 2019.

  1. gingertimmins

    gingertimmins Member

    its getting to that time of year where the garden needs a spruce up and I’m planning on painting the walls over the coming weeks.

    I’m wondering what to use to prime/seal the surfaces before painting....basically the cheapest, not the best product is what I’m after.

    One wall is unpainted cement render, one is bare breeze block and the other is painted cement render but that needs hacking off so will be unpainted cement render.

    Cheers
     
  2. KIAB

    KIAB Super Member

    Last edited: Feb 21, 2019
  3. gingertimmins

    gingertimmins Member

    That’s great advice guys, hadn’t thought of the dampness!
    It’s ok to re-render the wall now though, isn’t it?

    Also, same question stands. Can anyone recommend a suitable product.
    I’m more after type of product rather that brand if that makes sense
     
  4. DIYDave.

    DIYDave. Screwfix Select

    Surely if the surfaces - render, block, etc are in good condition, then you don’t automatically need to treat them with a coat of stabiliser

    Brush down to remove any loose sandy stuff, wash down if particularly dirty and/or treat with a fungicide wash if green stuff growing on them, allow to dry

    Only need to stabalise if surface is very dusty, flaky, chalky, and/or previously painted and paint is peeling off

    If bare render/block is in ok condition after brushing/washing, then treat as newly plastered wall and seal with a ‘mist coat’ of watered down masonry paint, then hit with 2 full coats

    I’m up against the pros here and sticking my neck out ...... comments guys o_O
     
  5. gingertimmins

    gingertimmins Member

    I’m of the understanding that it needs sealing due to the porous nature of cement/brick.
    Hadn’t considered a mist coat of masonry paint. Is that a thing?
     
  6. DIYDave.

    DIYDave. Screwfix Select

    Same reason as mist coating a newly plastered wall - thinned coat (mist) fully soaks into wall surface, acting as a sealer and a base for subsequent full bodied coats

    Depends on wall condition though
     
  7. Astramax

    Astramax Super Member

    A stabilising coat followed by two full coats of masonry paint is the manufacturers recommendation, stabiliser not necessary if wall surface is in a sound condition however if previously painted and showing signs of paint flaking off or has variable porosity surfaces a coat of primer sealer over the problem areas is the way forward.
     
    KIAB and Jord86 like this.
  8. DIYDave.

    DIYDave. Screwfix Select


    Bit like what I said .... cheers geez ;)
     
    George Coull likes this.
  9. Astramax

    Astramax Super Member

    Never had a call back for unsatisfactory work only for more work. Always played by the rules never was a chancer.
     
    KIAB likes this.
  10. Astramax

    Astramax Super Member

    Just clarified it David, brought it into focus.
     
    George Coull likes this.
  11. gingertimmins

    gingertimmins Member

    Thanks guys, when I say the condition of two of the walls is ok, I mean the render etc is sound but I’d guess it must have been like that for at least 5-6 years so I’ll opt to stabilise anyway.


    Thanks for the input
     
    George Coull likes this.
  12. DIYDave.

    DIYDave. Screwfix Select

  13. Astramax

    Astramax Super Member

    ...and your point is?
     
  14. DIYDave.

    DIYDave. Screwfix Select

    Well Astra, to paraphrase, from the data sheet that is produced for Dulux Masonry Paint

    Surface Preparation

    New or sound bare surfaces should be sealed with a thinned coat of Masonry paint, up to 1 -5 (water -paint)

    Surfaces that remain powdery, friable, chalky, seal with stabilising solution

    Note Do not seal sound new or bare surfaces with stabilising primer

    2 full coats of masonry paint

    So...... that's pretty much what I said in my first post

    I come on here to pass some time, read, learn and, offer some advice if I feel I'm able to
    Not interested in on-line arguing or politics or 'cock fighting', but happy to do so face to face with 'real' people

    Yes I'm diy but have a fair amount of practical experience gained from hands on home improvements

    I realise that there's more than one way to do any given task, in all trades, plus a lot of people will have their own favoured method
    But surely Dulux should know a thing or two about paint, prep and applying their own products ?

    That's it, nitey nite
     
  15. gas monkey

    gas monkey Well-Known Member

    when i painted the house a few years ago now the wife/boss got a gallon of some very posh sounding name for 17 i got a gal fo 9 no name i painted half gable down the middle she had to come up the scafolding and could not see the diference
    so lost faith in adds now two coats job done works every
     
  16. Astramax

    Astramax Super Member

    Calm down dear, go and put your hairnet on ready for bed, my paragraph was quoted from a trade handbook with specific regard to the preparation and painting for masonry

    Have a good day at work and remember your taxes are paying towards my pension.
     
  17. Tim-1984

    Tim-1984 New Member

    Good day to people. Hope everyone is well. I’ve been trying to find some advice on painting (repainting) my garden wall. It is about 3 meters long and 2 meters high, made up of standard bricks and mortar. It has been painted in the past but the paints a bit shocking to say the least. I need to scrub it down, removed all the random stuff growing on it, repoint it and then paint it. This thread has been a great help but also slightly confusing.

    If I scrub the brick work to remove as much as the old paint as possible I should be okay with using a mist coat (as per the advice above) then paint it. Question is in relation to the new pointing and potentially bricks with some paint residue on them and other threads I’ve read.

    Will there be any reaction between the paint and the new pointing due to chemicals in it?

    Should I seal it first as whilst it is new mortar and the brick work is sound (so don’t seal) it also has flaking old paint on it that may not all come off (so do seal).

    If you hadn’t guessed I’m a bit new to this and both comments seem valid but contradictory.
     
  18. Astramax

    Astramax Super Member

    Sorry for the confusion, follow post #7, or best to start a new thread.
     
  19. Tim-1984

    Tim-1984 New Member

    Good day to people. Hope everyone is well. I’ve been trying to find some advice on painting (repainting) my garden wall. It is about 3 meters long and 2 meters high, made up of standard bricks and mortar. It has been painted in the past but the paints a bit shocking to say the least. I need to scrub it down, removed all the random stuff growing on it, repoint it and then paint it.

    Should I seal it first as whilst it is new mortar and the brick work is sound (so don’t seal) it also has flaking old paint on it that may not all come off (so do seal)?

    Previous advice had been around one coat of seal and 2 coats of paint which is great however do I need to seal it as the brick work itself is fine but has patches of existing paint? I was planning on using Dulux weathershield, which again says not to seal if good brickwork. It’s a bit of half and half so I suppose either option could be valid hence why I’m a bit stuck?

    Any ideas or clarification would be great and it’s about what is best in this specific instance rather than in general please. In other words what would someone who knows what they are doing do in this case?
     
  20. Tim-1984

    Tim-1984 New Member

    Ta, I’ve started a new one as still confused. This thread has been great and lots of good discussion but I am stuck as to what to do in my specific situation. It’s halfway between the 2 scenarios.
     

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