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AuthorPosts
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May 15, 2018 at 1:44 pm #264
burton
25 PostsI’ve just bought some Wickes Vinyl Matt paint (beech hut blue) and have begun “cutting in” but the paint looks translucent and you can see the plaster beneath it. Should I apply an undercoat first? What sort of paint to I need to use for an undercoat?
Thank you learned friends.
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May 15, 2018 at 1:44 pm #265
jaz
22 PostsWater down some white emulsion (about 50%) and put a mist coat on or it will all fall off.
you will need 2-3 coats of your blue colour afterwards
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May 17, 2018 at 12:28 pm #302
burton
25 PostsWhat’s a mist coat? Do you still apply with a brush?
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May 17, 2018 at 12:28 pm #303
jaz
22 PostsJust watered down paint that seeps into all the holes and forms a good bond with the surface. Some people add a little PVA glue as well as water down paint but it’s not really required.
Can be applied with a brush or a roller, but it’s messy as it’s really watery
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May 17, 2018 at 12:31 pm #307
FUZZY
15 PostsNo to PVA. It’s an old wives tale.
A cheap matt emulsion is your best bet.
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May 17, 2018 at 12:31 pm #308
oldfogie
5 PostsNo PVA. Don’t use vinyl matt for the mist coat, use contract matt. Get snots off with sandpaper first. You can get sander that goes on a pole if you have other rooms to do. Caulk after the mist coat (use non-cracking).
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May 15, 2018 at 1:44 pm #266
dave
13 PostsYou should first go all over the plaster and give it a light sanding.
Mist coat and cut round the edgeslight sanding
first proper coat.
light sanding
possibly last coat.
How do I know. My daughters fiancee has who has just fully painted our house did it this way on new plaster and the finish is awesome.
I asked if all the sanding was nesecarry and he said only if you want a proper finished job.
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May 17, 2018 at 12:29 pm #304
keith
10 PostsAssuming this is new plaster you are painting? If so, then, as suggested by others, a light sand and a mist coat is the the thing.
A light sanding is all you should need: if it’s new (decent) plaster the surface should be flat and fairly smooth so it should just need any knibs removing, then sanding to provide a key if the plasterer polished it a bit too much. You just want to remove any shine,no need to go overboard. Just ‘float’ the sanding block over the wall and you should feel any imperfections. Ideally, try to look along the wall with a window/light-source at the other end and you will see any knibs or other imperfections.
It doesn’t sound as if doing this would make much difference but, as bedspring said, it really makes it look smart – assuming your painting is up to scratch, obvs.
Tip for the mist coat: dilute about 1:1 but ensure you give it a really thorough stir, ideally use an electric paint whisk, otherwise you’ll end up with water on some of the wall and thicker paint on the rest. The mist coat should look fairly even and well-covered.
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May 17, 2018 at 12:29 pm #305
pakpak
14 PostsIve never heard of needing to sand fresh plaster, the finish should be such that it is free of imperfections….i served my time trowelling the stuff onto the wall.
Priming the wall with a watered down emulsion will suffice but again not strictly necessary, a decorator told me not all emulsions are created equal, with trade paints formulated differently for just this purpose.
Ive just re-skimmed my loft conversion, no priming, just deluxe trade paint straight onto the plaster.
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May 17, 2018 at 12:30 pm #306
keith
10 PostsIt’s more a case of lightly going over any well-polished patches to provide a better key, no need to sand the whole wall (unless it’s all been highly polished). Removing any knibs, bits that have been left on corner beads etc is just fine-tuning; it wouldn’t stand out if it was left but it makes the job that tiny bit smarter. You’d never see guys on the sites doing any of this, it’s only something you’d maybe take the time to do on your own house, or see a really high-class painter doing.
I’ve heard some paints can now be applied without a need for a mist-coat but some still definitely do need one and mention it in the MI’s.
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May 17, 2018 at 12:33 pm #309
Sammyf
14 PostsWhat are people’s opinions on undercoats versus overcoats? I’ve found that when glossing it’s better to do enough undercoats to give a uniform surface colour before a single coat of gloss, rather than a single coat of undercoat and multiple coats of gloss.
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