Plastering Beginner's Guide

Plastering

The Plastering Beginner's Guide is designed to help get you up and running.

This article is not intended to be a complete treatment of plaster or plastering, rather it is meant to be a simple, straightforward and easily digested starting point. To read full detail about this subject, see Plastering.

Skimming

How to skim

Plastering, like anything else is easy if you follow a tried and tested method:

Get the wall ready first, don't start mixing until you have done this...PVA over everything, except plasterboard, you can apply the skimming while this is wet or dry....if the wall is p-board, get it scrimmed up all along the joints and make sure no nail/screw heads are proud.

1. mix
2. get a coat of plaster on the entire wall, don't bother about any marks, lines or anything else, just make sure the entire surface is covered fairly evenly (even as in the same thickness - don't have it a mm in one part and half an inch thick elsewhere, unless this is unavoidable.)
3. Wash your trowel, bucket etc and clean the mixing bucket and then have a brew.
4. 10 mins later, do another mix, half the size as the first mix.
5. apply this t-h-i-n-l-y over the now partially set first coat, you are only really using the new mix to fill any hollows and you will see that it is much smoother already than the first coat.
6. wait 10 more mins when you've finished the 2nd coat, then with a clean trowel and clean water, splash a small amount of water on the upper left section of wall and work your way L-R, then the same at the bottom. (the handle side of the trowel should be kept clean at all times, if any bits of plaster are visible when looking down at the blade, clean them off, have a wet brush and bucket at all times when plastering).
7. repeat number 6

Some people attempt to do large walls in one coat, but it's false economy, firstly, it saves them 75p worth of plaster, but they spend longer trying to get a decent finish on it, and secondly, because they think they are saving time by 'not doing it twice', instead they end up going over it a dozen times trying to get it right, whereas with the method mentioned above, it gets two coats, laid down once and finally polished, but there's less effort goes into those 'four times over' than 'one coat and struggle for hours'...the end result is a smooth finish suitable for painting, if the walls are to be wallpapered and it's your own house, you can leave the final polishing, but for the sake of an extra 30 mins easy work per wall, it's not worth leaving.

How to skim - variation

From personal experience of an absolute numpty beginner, based on Ron The Builder's How to plaster a wall

This may not be the professional way and there may be much scope for improvement, but I achieved quite passable results immediately. Not professional standard by any means, but good enough and hopefully practise will help.

1. Follow above guide regarding preparation and PVA-ing over friable substrates (I use a 5:1 water:PVA mix) and further PVA-ing over the lot, if there's any paint to be covered (I use a 3:1 Water:PVA mix for this)
2. Mix the plaster (I use a MultiFinish plaster, fresh as possible) until it's like whipped cream (a power mixer tool on a power drill or SDS makes this easy and avoids lumps).
3. Apply plaster mostly evenly but don't fiddle with it. You have about 30 minutes to get this done before the mix starts setting.
4. Have a brew - very important. At first, do not attempt to be clever and do anything else, other than wash your tools. Keep any spare mix on the board.
5. Watch the plaster, occasionally poking it.
6. When the plaster is becoming cheesy in consistency (another 15-30 minutes later, depending on how quickly you got the first coat on, going the way to Play-Doh or putty in consistency), take your clean trowell and flatten the plaster, with the trowell at a shallow angle. This is much easier now it has set to a semi plastic state. Any obvious gouges or low spots may be filled with what's left on the board, but don't worry about perfection. It will look not very good at this stage but don't worry. Do your best to get general overall flatness though.
7. Clean tools and board
8. Wait for plaster to become quite firm - another 15-30 minutes. It will still be damp, which is what you want.
9. You may wish to gently trim edges of your back boxes with either a sharp knife or the edge of a small pointing trowell - it's easy at this stage. A good time to gently remove any excess that may have escaped round an internal corner.
10. Mix perhaps half the amount of mix you did the first time, perhaps just a fraction wetter - but not too wet.
11. Apply very thinly with a scraping action. You aren't trying to put another thick layer on - rather you are trying to get plaster into the hollows as defined by your trowell. Because the first coat is not fully set and damp, the plaster will blend surprisingly well (well I was surprised!)
12. Do this over the whole wall - this will be a quicker session than the first coat. You can aim for general perfection here, but don't worry about the odd ripple the trowell leaves.
13. Wash your tools and give it another 15-30 minutes until the cheesy stage is reached again, keeping your leftover mix on the board.
14. Have another brew and watch the plaster.
15. When it's got to the cheesy stage, flatten in any slight ripples or marks. If you discover a small low spot or a gouge, you can still work some leftover mix in provided it's no firmer than putty. A spray of water from a plant mister can help the trowell move nicely, but don't overdo it as the gypsum is very soluble at this stage and sloshing water everywhere can leave run marks.
16. Trim any excess from internal corners, external corners and back boxes. Careful - pulling motions can dislodge lumps - try to cut into the plaster rather than pulling away.
17. A 2-3" paintbrush dipped in clean water can now be used to gently run round all internal corners - this should blend the corners in quite nicely.
18. Clean your tools and board and site and admire your work with another brew!

Tools

Trowell

A plasterer's trowell is flat (ish) and rectangular with a handle centrally mounted on one face.

Trowels...you can rub the sharp corners off on a brick if they are giving you too much grief, just make sure there are no 'burrs' on the face of the trowel side...they only need half a dozen scrapes on each corner, just to take the sharpness out.

Another alternative, I recommend for beginners like myself is to buy a pre-formed stainless steel trowell, such as the Marshalltown Permashape. I used an old flat trowell and a Permashape in alternation and there is no comparision in the ease of use of the latter.

Hawk

Hawk: Needed to load the trowell and to scrape the trowell off with. Available in metal and plastic.

Mixing

You will need a bucket - something with a flat bottom and smooth sides and something to mix it with. This can be a stick, which will be hard work for larger amounts but is still viable for smaller amounts.

Or you can buy a power mixer: A helical mixer tool on a reasonably powerful electric drill makes a fine mixing device. Beware of overloading underpowered drills - you need to run it for a few minutes at a time. Real plasterers will often have a dedicated power mixer. The tool is much the same but there's a more powerful motor with a double handle for easier handling.

Cleanliness

You must keep everything clean! Clean clean clean! Lumps on the board or hawk will break off into your mix and ruin everything. Crud on your trowell will remove any chance of a decent finish. If you have the luxury of a garden and a hose, simply take stuff outside and give everything a good blast with the hose. Gypsum is not bad for the ground and may even be good if you have clay soil. A hose is a very fast way to maintain shiney clean buckets and tools.

See Also

• Discussion of patching
• Ron The Builder's How to plaster a wall
• Wiki Contents
• Wiki Subject Categories