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Painting onto new plaster - do i need to sand walls before painting?
We've just had our walls skimmed, and we're now ready to paint them. Some places are recommending sanding the walls before painting. Is this necessary if they've just been skimmed? Or can we go straight to the water down emulsion as a primer for the walls?
33 Answers from MyBuilder Painters & Decorators
The answer to your question really depends on the standard your plasterer has finished the walls to. Sanding down the walls with a medium grade sandpaper can ensure the surface is free from any imperfections such as splashed plaster and grit/dust and ensure a good surface for the paint to adhere to. However, if the walls are smooth to the touch and appear free from any such imperfections then you should be fine to apply your mist coat.
If you do chose to sand the walls, ensure you use a medium to light grade sandpaper (such as a 120grit or above) as using too coarse of a paper may scratch and mark the walls.
I hope this helps!
Neil Bird & Son
Answered 13th Sep 2014
I always give new plaster a quick "key" with a 120 grit sandpaper. Doing this creates a pourous surface for the paint. Then I mist coat at a 60/40 paint to water split. This will then show you any other imperfections that are visible in the wall. You can then rectify these before applying your 2 top coats. Hope this helps
Answered 2nd Apr 2018
Hi walls should never have to sanded if they have been skimmed by a professional plasterer. The wall should be smooth like glass and shiny. If you look along from a narrow angle you can see a reflection. If this isn't the case I would recommend light sanding only where needed otherwise imperfections could show up after paint is dry.
Answered 12th May 2017
Glass finish is bad for paint adhesion and hand applied plaster will always have small imperfections
Ask any painter
Answered 29th Nov 2017
I would always scrape down newly plastered walls to take off any nibs of plaster off, making sure the areas are completely dry i would then proceed to rub down area with a medium grade sandpaper to allow the miss coat to penetrate the wall. I would normally wipe down area with a damp cloth to make sure the area is free of dust and once dry apply a 50/50 emulsion and water mixture as a miss coat to seal all new plaster, once the miss coat has dried your free to either fill walls if needed or start to apply your wall or ceiling colour. A useful hint is to put a splash of water to emulsion as it rolls on the wall better and leaves a flat finish, rather than heavy stipple. I hope this helps.
Answered 12th Oct 2018
NEVER RUB DOWN NEWLY PLASTERED WALLS!! before the mist coat has been applied,
You’ll end up scratching the plaster surface, You always prepare surfaces between paint coats, steps to follow.
1) mist coat
2) prepare surfaces e.g fillers/sanding down
3) apply 2 coat to surfaces
4) prepare surfaces e.g fillers/sanding down
5) spot prime any filler surfaces that was done in section 4
Now surfaces should be 100% before the final coat is applied
6) apply final coat
Follow these steps and any painting surfaces will be perfect
Hope this will help
Answered 5th Jan 2020
Almost always sanding required especially in corners. Use 180 grit. And Hoover as much as possible be painting
Answered 23rd Nov 2017
When applying paint directly to new plastered walls it’s always good practise to lightly sand the wall with 120grit sandpaper. The main reason is to give the paint a key, especially If the plaster is shiny and super smooth the paint will not key/bond to the plaster.
For your first coat of paint always water down the emulsion based paint with clean water at a ratio of 50/50.
This dust coat as it’s called will show any imperfections in the plaster, these can then be sanded, dust coated and once dried, painted with at least two coats of paint.
As a little tip it’s cheaper to use white as your dust coat paint as this will not affect the top coat colour
I hope this helps
John Martyn Interior Solutions
Answered 9th Mar 2019
Hi tom i find the best way to know whether your plaster work is good or not is to water down your paint and give it a miss coat and then a first coat so then once you have that on your wall or ceiling you can see a lot better if you need to sand down or apply filler to your walls because if you fill or sand down before applying a coat of paint to a plaster wall you dont get the whole picture of how good the wall is and if there is any prep needed.
Answered 25th Sep 2018
Myself I would not sand down any freshly plastered walls but you would have to look 1st to see if there was any small imperfections throughout the wall but I would just go ahead mist coat on and I would recommend using a 60 40 when preparing your paint
Answered 7th Jan 2018
It is only necessary to sand the walls if the finish of the plaster is not perfect .However if you are sanding the walls use a sanding paper that is over 120 just so you make it very smooth to the touch . After , when you are happy with the walls you have to make sure there is no dust left on the walls as it might damage the aspect .Finally you can apply the emulsion on the walls and the result will be the one you hoped for .
Answered 30th Jan 2018
Depending on the finish as most of people said, I usually apply the first / miss coat, after that feel the wall I find it highlights it more, then give it a light 120 sandpaper rub it doesn’t need a great deal just a rub over which should relieve all grit under the surface, as sometimes you can also get (if the plastering isn’t that great) you can get the grit in the paint which will make the walls rough so a light rub for the extra smooth finish is always what I go for!
Hope it goes well for you!
Answered 24th Oct 2019
Remove any snots or plaster build up on edges and corner with light de nibbling
Then you have a couple of options
Zinseer gardz to seal plaster then on with chosen topcoat
Or Tikkurila optiva primer as you miss coat
Or look at data sheet of paint which might say some like like
On bare plaster dilute 1st coat 20% or so
But if it doesn’t say that then
I would use optiva primer or zinser gardz
Far superior adhesion to plaster and subsequent coats
Than any cheap diluted contract matt which you can scratch of easily
You want maximan adhesion and in my option cheap contract Matt diluted is
Answered 26th Nov 2019
Hi Tom the answer to your question really depends on the quality of plaster sanding down the walls with a 120 grit sandpaper can ensure that there are no imperfections on the wall and when the walls are smooth to the touch you should be ok to apply your mist coat.i hope this helps Patrick
Answered 13th Dec 2017
Manchester • Member since 14 Jun 2018 • 278 jobs, 97% positive feedback
Hi it depends on the finish the plasters have left .should just need pva sealant first then painting in the colour of your chose.
Hopethos helps joe.
Answered 29th Nov 2018
If the walls are still uneven and have alot of trowl marks in them I would firstly get the plasterers back on a snag and get them to sort it! You should never sand new plaster as it will scratch the surface once you have mist costed the wall you should always pole sand between coats. You will also sand again after the first fill and that would get any snotts or imperfections in the plaster. Hope this helps.
Answered 10th Jan 2019
Hi Tom, I find it better to go on with your mist coat first (mix of paint and water). Then this helps to emphasise any defects. You can tackle them easily with a 240 grade sandpaper. That being said, a good plasterer will have left you with little to no issues of this kind and a mist coat followed by top coats should be all you need.
Hope this helps!
Answered 12th Nov 2018
Blyth • Member since 8 Jan 2019 • 13 jobs, 100% positive feedback
You should never sand bare plaster as it scratches the finish. You should always put a mist coat on to bring out any defects in the wall e.g. filling and sanding. You should then apply your finishing coats following the preparation needed.
Answered 9th Jan 2019
I always sand a wall down before and between coats using different grades of sabdpaper will help to get the best result
Answered 11th Jan 2019
Running A flat hand hald blade over the plaster to “de nib” any uneven plaster and plaster splatter can’t hurt,
You can then apply a “contract emulsion” by brush and roller this first coat once dry will show up any imperfections in the plaster which you can then address before applying finish coats..
Slight drop of water in the first coat will make coverage easier.
Hope this helps
Answered 23rd Jan 2019
First, use a lamp: put it on the wall parallel to it, check for imperfections; if so, then surely you have to sand before painting. By the way, there is no perfect plastering 100% :)
Answered 23rd Jan 2019
you can just paint if they plater did a good job
Answered 5th Mar 2019
Hi Tom, sometimes a light sanding might be necessary if you can see some minor imperfections in the plastering. Opting for a light to medium grade sandpaper should prevent you from overly sanding down the surface. If you use a sandpaper that is too coarse, you may find that you end up scratching your walls.
Hope this helps.
Answered 31st Mar 2019
If the plaster was done at a high quality don't need sanding. If there are imperfections i recommend to sand it with 180 grid sanding paper just to dont scratch the plaster. You will need to apply contract matt paint first and then do the top coat
Answered 11th Apr 2019
This is depends on your plasters
if the walls are smooth to the touch and appear free from any such You don’t need to ! But if the walls is got scratch or lines then usaly we put a light sandpaper 120 grit
Answered 20th Dec 2019
Hi it’s all ways best to give slight rub down. As this will get any imperfections out the plaster
Answered 24th Apr 2021
I would definitely rub the plaster down but making sure it’s completely dry.then I would put a miss coat off watered down emulsion to draw into plaster let it dry after afew hours apply your first coat off paint hope this has helped you.
Answered 28th Aug 2018
Grimsby • Member since 9 Nov 2018 • 2 jobs, 100% positive feedback
Myself I would not sand down any freshly plastered walls but you would have to look 1st to see if there was any small imperfections throughout the wall but I would just go ahead mist coat on and I would recommend using a 60 40 when preparing your paint.
Once mist coated it is then easier to see any imperfections for filling.
Answered 29th Dec 2018
If the walls are smooth to touch, you can apply your mist coat, if you have slight imperfections then I'd suggest to lightly sand down with a low grade sand paper.
Answered 9th Jan 2020
If the plaster is not good
Answered 21st Jan 2020
If there is any visible dust or any imperfections on the wall then sanding the walls before painting is recommended.
Answered 6th Jun 2020
It is recommended to use undercoat for the walls before painting and after sanding.
Answered 22nd Oct 2020
Hello, before sanding the walls I recommend doing the mist coat first which is 50-50 of white emulsion and water then it will make it easier to see the imperfections, from there I would use a worn down piece of 120 sandpaper and rub down the imperfections and fill if needed. If you use sandpaper on the bare plaster it will scratch the plaster causing it to need filling
Answered 17th May 2021
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