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questions for painting on newly plastered walls

Discussion in 'Decorating and Painting' started by VickyBH, 5 Jul 2019.

  1. VickyBH

    VickyBH

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    I've not done any painting on the wall before so please forgive me some questions seems a bit silly.

    I need to paint kitchen walls that's been plastered, some were done 2 weeks ago, some just been completed yesterday. After some googling, many use either No Nonsense Bare Plaster paint or Layland Trade Contact Matt emulsion (dilute down).

    Is there any real difference between these two in terms of paint quality, how well it sticks to the surface? I went to Brewers but they told me Albany SuperCover is the best, and I'm a bit confused because I can't find any info on google.

    I also have question about timing.
    How soon can I start mist coat after plastering?
    Is there a optimal time between each coat? (i.e., can I leave mist coat on for days/weeks before the final 2 coats? Can I also paint final 2 coat as soon as mist coat is dry?)
     
  2. toomuchtodo

    toomuchtodo

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    Best waiting until the plaster is completely dry before applying mist coat.

    If using bare plaster paint then I think it's designed for applying to wet plaster (as is a contract matt mist coat but I still.orefer it to be dry) but it's expensive compared to a watered down trade emulsion.

    There's lots of opinions on how best to mist coat ranging from simply following instructions on the tin to adding 10% water to anywhere as mu h as 50% water.

    Friend of mine has been a painter and decorator for 30+ years and has always sworn by 50/50 so that's what I've always done for the initial mist cost and I've never had an issue. Until....

    I mist coated the plastering in my new extension using a 50/50 mix of Leyland Trade emulsion. It was only after painting that I noticed the plastering must have been done with a spoon. Put simply, it was horrific. So bad that I really should have noticed it before I painted. I had two options - have it re-skimmed or sand it back with a monster sander.

    I opted to get a quote to re-skim, call the builder, get him round to see it and agree to refund the cost of the quote because I didn't want his guys trying again and then getting it skimmed. Unfortunately I was let down at the last minute so had no option but to tackle it with the sander. Bare walls would have been fine. Easy almost. However, as I'd already mist coated, the paint formed this super tough glass like coating over the plaster within 60 seconds of replacing a sanding disk which meant I was going through sanding disks like there was no tomorrow.

    No idea if less water would have made it easier to remove the paint but a 50/50 mix really does soak in to the plaster and forms an almost impenetrable layer.
     
  3. VickyBH

    VickyBH

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    Thanks for sharing the experience. Did you mist coat once or twice?
    I was going to tackle imperfection with filler and sander after mist coat, would you say it’s better to tackle it on bare wall before mist coat if I can see the imperfection already?
     
  4. toomuchtodo

    toomuchtodo

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    Just once, then spent three days (it's a big space) sanding it all off. Probably would have only taken a day if I hadn't already mist coated it.

    Always mist before filling. My mistake was not looking at it and seeing how bad it was before mist costing.

    So, mist, fill, sand, spot prime filled bits, then paint.
     
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  5. opps

    opps

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    As suggested by toomuchtodo, contract paints are a bit of a bodge, they have a very low acrylic content and primarily designed for painting plaster/internal render that hasn't quite dried yet.

    I seldom use those kinds of paints, the low acrylic content makes it very difficult to keep them clean.

    You don't mention if your walls were bonding plus skim ot just skimmed plasterboard. The former can take quite a long time to dry, the latter, 3 days or so.

    Opening windows massively increases drying time (that holds true even in the winter).

    With regards to how much you thin the paint, as a professional decorator, I just follow the advice on the tin. I would only ever consider a 50/50 if I knew the plaster was really bad and would need lots of sanding, however, I would be able to see that before applying any paint and would therefore sand the walls before applying any paint (and thus wouldn't be using a 50/50 in the first place).
     
  6. VickyBH

    VickyBH

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    Thank you (both) for the very helpful advice. What paints do you use if not contact matt?
    The plasters in kitchen are very mixed, some were stripped back to bare brick so Hardwall+multi, some were bonding+multi due to tile removal damage, and there's a bit of plasterboard too over RSJ.

    What's the adv and disadv of sanding/filling plaster before any painting? (I take it you meant before mist coat too.) Almost all the post I came across said don't sand before mist coat. I was just wondering why is it so.
     
  7. opps

    opps

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    I normally use bog standard Dulux Trade matt emulsion (note: Dulux Trade and not the retail/DIY Dulux).

    An advantage of the of the 50/50 is that if you then discover high spots in the plaster, a when you sand through the paint you won't have to worry about trying to feather out the paint. BTW the 50/50 mix is often referred to as a search coat (ie one that shows you flaws in the plastering.

    I have no idea why the other posts recommend that you don't sand before applying the mist coat. I can only imagine that the authors are worried about the walls becoming dusty. I sand the walls with sanders connected to dust extractors and then I vacuum the walls.
     
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