Hi Tom,
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!
Lee.
Neil Bird & Son

Glass finish is bad for paint adhesion and hand applied plaster will always have small imperfections
FACT
Ask any painter

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

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.

Hi Tom
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.

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

Almost always sanding required especially in corners. Use 180 grit. And Hoover as much as possible be painting

Hi Tom
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

Hi Tom.
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 .

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.

Hi Tom,
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
Kind regards
Martyn Dimblebee
John Martyn Interior Solutions

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
Not it!

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

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.

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.

Hi Tom,

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!

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!

David
Expert-HI

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.

I always sand a wall down before and between coats using different grades of sabdpaper will help to get the best result

Hi Tom,
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
Carl
C.W DÉCOR

Hi Tom,
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% :)

Hi Tom

you can just paint if they plater did a good job

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.
Adrian

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

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
Thanks!

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.

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.

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.

If the plaster is not good
Definitely yes

Hi Tom,

If there is any visible dust or any imperfections on the wall then sanding the walls before painting is recommended.

Hi,
It is recommended to use undercoat for the walls before painting and after sanding.
Best luck