Hi folks, my name’s Sam from Helpful Home
DIY and today I’m going to very quickly show you how to prepare plastered walls for painting.
Mostly using this stuff to be honest. OK, so if you’ve just plastered your walls yourself
and they’re not quite bang on perfect, or if you’ve had a plasterer in, and there’s
a few bits here and there that need sorting out before painting. I recommend you spend
a bit of time getting that right, it’s far easier to sort it out before you paint. The
first thing you need to do is to check to see how bad the wall is. There is a very easy
way to do this, obviously just looking at it. But the other way is if you get a torch
or a lamp or something, and shine it along the wall so that it casts a light along the
wall. And then any lumps and bumps that cast shadows will be easy to spot. And obviously,
once you’ve done that you can get onto sorting them out. So I’ll jump straight into it and
the first one is very basically just sanding down the plaster. Ok, so if you’re plastering
the wall yourself and you’ve not done it much before, if at all, like me. Then you’re bound
to have some dips and bumps and things like that that you need to sort out, it’s inevitable.
If you got a plasterer to do it and you have some lumps and bumps then call him back and
have a few words. But, it’s quite easy to sort these bits out, so don’t worry. All you’ll
need is 120 grit sandpaper. Obviously, if it’s a big bump then you want to look at filling
it in. But anyway, 120 grit sand paper. I’ll just use this one as an example. You just
rub it round in a circular motion and it actually just smoothes it out nicely. So we’ve got
some fine dust on that. Now you’ll notice I used my hand to do that. Don’t press too
hard, use the flat part, don’t fold it, just let the sandpaper do the work. And you’ll
see that it quite easily just smoothes out the lump. Try not to use sanding blocks with
this because you don’t want to get a big area. Just locally around where the lump or the
bump is. That’s a bit dusty, just give it a wipe. Nice and smooth. So, a few other things
I had to do to sort out my plaster because it was the first time I’d plastered. The first
couple of walls in particular I had lumps and bumps all over them. So instead of sanding
all these individually, what I did was I just got a vibrating sander and it has a pad about
that big where you attach some sandpaper on and you just do the whole wall in a oner.
It created a lot of dust but it’s spot on. I mean I’ve painted it now and it looks great.
So the other place you need to think about is along the corner beading of the windows.
Remember, we put the metal strip in there, yours might be plastic. So you can just see
some of the metal here but in some places, the plastered a bit sort of lumpy. And that’s
fine, what you want to do is just sand that off down to the metal itself. Just to get
that nice and straight edge. OK, so you can see the metal there and that will give a really
nice clean edge. Where there are bits of plaster sort of branching out, which happens when
you’re plastering it, don’t be tempted to get at it with a scraper because it’ll just
knock off big chunks. Unless it’s a big lump coming out that is. If it’s a particularly
big lump then using a 120 grit sandpaper will probably be a bit slow. So start of with something
like 80 grit, and maybe even 60 grit. And work you way to finish on 120 grit. If you’ve
got quite a few lumps and bumps and you obviously need quite a bit of sandpaper to even them
all out because it fills up the pores in between the sandpaper quite quickly with plaster.
Good sandpaper, this stuff here is brilliant, there you go. Good sand paper, it’ll cost
a bit of money but to save a bit of money, just because it’s clogged up, doesn’t mean
it’s still not good for using. You just need to get rid of the plaster. There’s quite an
easy way of doing that, hoover with a brush attachment. Good to go. One other common problem
is, when it comes to painting, is it sometimes, even with a mist coat, so watered down coat
of paint, it doesn’t adhere to the plaster. The number one reason for that is because
the plasters been shined off too much, the final skim of plaster has been worked so much,
with some water, that it just looks like a sheet of glass. Well a pink sheet of glass,
but it looks really shiny. You’re not actually meant to do that as a plasterer. Because,
obviously, it’s so shiny that the paint can’t stick. But there is a way to sort it out.
Just get some fine sandpaper, 100 grit or 120 grit and just lightly go over that. It’ll
get rid of the glossy surface and it’ll give the paint something to attach to. And finally,
there might be where you’ve got some gaps between the edge of the plaster and the architrave.
That’s a wooden frame around the door frame. Or maybe the odd gap here and there in a corner.
The best thing to do with those is literally make a little mix of plaster and fill it with
the trowel so that it’s nice and flush with your existing plaster. Those kind of fill
in bits are susceptible to drying out quite quick, mostly because they are attaching to
the old plaster which will suck out moisture. So just keep an eye on those and just have
a painters brush and a tub of water or something like that to hand so that every ten minutes
for the first say hour to an hour and a half, it looks like it’s started to have some cracks
form where it’s dried out too quick. Just get the brush and water and just paint over
that and what it will do is it will just blend that gap with the rest of the wall. like I
said, for the first hour to an hour and a half you’ll need to keep an eye on that. And
finally, one last thing, it’s slightly going off topic but it’s regarding the next step
in the process, which is putting the first coats of paint on the newly plastered wall.
I want to say this now before you go ahead and paint the walls is don’t cover it with
PVA. You’ll see why in my next video which will be about painting the first coats onto
that plastered wall. But for now, just don’t put PVA on the plaster. Ok folks, a very quick
one but thanks for watching. I hope you’ve found that useful. If you’ve got any other
suggestions on how to prepare plaster before painting, please leave them in the comments
section below and I’ll respond and everyone can benefit from your question and my answer.
Please subscribe to my channel, it all helps. And, as always, I put a little bit more information
on my website, so if you go to www.helpfulhomediy.co.uk , and then on the menu at the top, in the
how to bit, click on that and then you’ll see the blog post for this, where I just put
a bit of extra information. OK, thanks for watching, see you next Saturday. So, I’ve
sanded down the plaster and…. This is for the… What’s this for? [whistling]