Sanding walls - by hand or machine?

goodwithsaving

Hello! Having spent days scraping off wallpaper, I am ready to prepare the walls for painting. I have a few large rooms to do, and am feeling weary of it with my back aching and so forth. 
To sand the walls ready for painting, would an orbital sander be good for the job, and not too abrasive? (Fine sandpaper discs). I have seen painters used mechanical ones but I don't think I a) have the time or b) have the will

Thank you. All tips appreciated. I will buy a dust mask

Martin_the_Unjust

Hmmm sanding walls prior to painting is really (in my experience) only done to smooth off any filling you’ve done and or to key the surface for paint (fine sandpaper and a light rub)

If you are planning to sand whole walls to smooth them off, then good luck to you and I hope you like hoovering dust up.

NSG666

Try these with some 180? grit

Swivel Sander Head (toolstation.com)
Pole (toolstation.com)

TELLIT01

If the surface is so bad that you are having to sand the entire wall, you might be better off getting them skimmed.  There is a cost obviously, but likely to get a far better finish.

goodwithsaving

TELLIT01 said:

If the surface is so bad that you are having to sand the entire wall, you might be better off getting them skimmed.  There is a cost obviously, but likely to get a far better finish.

Unfortunately finances don't allow that and won't for sometime. It's about getting a suitable finish now and probably reskimming at a later date. We're talking a few years before I will be able to afford to do it as I have other things which are more urgent

NSG666

How bad are they? Give the walls a good wash down to get rid of the wallpaper paste, patch the bad bits you can see with e.g. polyfilla easy sand and/or paint with a cheap contract emulsion then check and fill imperfections and paint. If the walls are good or you don't want to use contract matt then give them a coat of colour then check and fill imperfections.

Leyland Trade Contract Matt Emulsion Paint Brilliant White 10Ltr | Emulsion Paints | Screwfix.com

Bendy_House

GWS, first get every trace of wallpaper paste off the walls. Then let it dry fully.

Try the setup suggested by NSG. Yes it can be hard work, but actually you shouldn't have to press hard into the surface, so it could be easier than you fear. Go at it in long steady sweeps. Give your self lots of breaks. Have good music playing loudly. Wear a mask...

It really comes down to how bad the surface is. Once the paste is off, could you posts some photos taken at a low angle to the surface to show any undulations, bumps and pits? If it's really rough - some obvious high-spots - then you might even be able to lightly use 80 grit to remove the bulk, then go to 120 (which might be good enough for the final finish) or 180.

Once you've rolled on a mist coat and at least 2 neat coats, you may be surprised at how good it is.

When the mist coat has dried, you'll have a better idea of the state of the surface, so that could lead to "It's ok" or "A bit more sanding...".

goodwithsaving

NSG666 said:

How bad are they? Give the walls a good wash down to get rid of the wallpaper paste, patch the bad bits you can see with e.g. polyfilla easy sand and/or paint with a cheap contract emulsion then check and fill imperfections and paint. If the walls are good or you don't want to use contract matt then give them a coat of colour then check and fill imperfections.

Leyland Trade Contract Matt Emulsion Paint Brilliant White 10Ltr | Emulsion Paints | Screwfix.com

That's exactly the tub I have bought :-)

Thank you for the advice. I will do that. Likewise @Bendy_House
I wanted to remove the wallpaper because that's the bit that I just couldn't stand, but I can live with slightly bumpy walls for a couple of years, I'm sure it won't be noticable after a bit of elbow grease with sandpaper. I will buy the grits you have suggested, Bendy. 
At least it burns off any snacks...

NSG666

goodwithsaving said:

NSG666 said:

How bad are they? Give the walls a good wash down to get rid of the wallpaper paste, patch the bad bits you can see with e.g. polyfilla easy sand and/or paint with a cheap contract emulsion then check and fill imperfections and paint. If the walls are good or you don't want to use contract matt then give them a coat of colour then check and fill imperfections.

Leyland Trade Contract Matt Emulsion Paint Brilliant White 10Ltr | Emulsion Paints | Screwfix.com

That's exactly the tub I have bought :-)

Beware that as a contract matt it's not very durable. On ceilings it's great as you won't touch it but I did my walls with the magnolia version and it went quite powdery feeling and would come off on your clothes if you happened to brush against it.

Grenage

I fill imperfections and then I sand the whole wall, every single time.

I use an orbital sander attached to a wet and dry vac.  No dust issues (but still wear a mask.

A roll of 180 green grit goes a long way.

FreeBear

NSG666 said: Try these with some 180? grit

Swivel Sander Head (toolstation.com)
Pole (toolstation.com)

Probably the best tool for the job. A double angled sanding block (sponge) will be useful around the edges & corners. An orbital sander is just way too messy even with dust extraction. With power tools, there is a real risk of gouging out chunks of plaster. On top of that, you need a really good fitting dust mask & overalls and you need to seal off the room from the rest of the house to limit dust traveling.

If you must use power sanding, get a spray bottle and liberally mist the air as you go. The water droplets will help to collect the dust in the air and limit the amount kicked up as you move around.

If the walls are in poor condition, a heavy duty lining paper will cover up a lot of sins and give you a good surface to paint on.