Plastering a wall or ceiling takes practice to achieve a smooth flat surface for decorating, but if you’ve had enough practice on smaller areas and feel confident enough to get a reasonably good finish on a small wall such as in a bedroom then reading this article could help you.
Having everything ready and to hand before you start is a must and going through it all in your mind so you know each procedure will help to make it all run smoothly.
Preparation
The surface to be plastered has to be sound with no holes deeper than two millimetres before you begin and all flaky or loose material should be sanded down and or washed off.
Loose plaster can be made good by hacking off and filling with filler and left to dry.
Clear all debris or furniture away to have a clear and clean work area and then put a table with a board close to the wall to be plastered; this is for the wet plaster to be put on as you plaster the wall.
An absorbent surface must be bonded or it will suck the moisture out of the plaster as you’re doing it and it will go hard and be unworkable.
To find out how absorbent it is, flick a few drops of water onto the surface of the wall and see how fast it soaks in. If very absorbent then paint the wall with a solution of five parts water to one part PVA that is well mixed and allow to dry thoroughly.
It’s important for the surface to be sound with the same absorbency rate throughout and this is why PVA adhesive is used to bond the surface so the plaster goes on easily at the same rate and stays workable until flattered down and finished.
After the five and one mix of PVA has dried it is ready for the three to one mix of PVA which is put on just before plastering and mustn’t be allowed to dry.
Most walls and ceilings will not be too absorbent and so a three to one mix of PVA can be applied and left to go tacky just before plastering.
You will know when it’s ready when you touch it and your finger pulls the tacky PVA away with it.
Plastering...
The wall is now ready for plastering with thistle multi-finish plaster.
Mixing plaster is best done in a large bucket at least twice the size of a normal one. Pour in approximately four inches of water into the bucket and then add plaster from the bag by either using a scoop or having someone help you by pouring it in as you mix it. Plaster is mixed up at a 50/50 rate of water to plaster.
Mixing can be done with a stick but it’s hard work to mix it properly.
The best way to turn the mixture is with a powerful drill with a mixing tool attached. As the tool is spinning in the water, plaster is added until it becomes thick enough to apply to the wall.
When the plaster sits on the trowel without sliding off and is of the consistency of soft ice-cream then it is ready. I always use a stick stuck in the middle of the plaster that stays upright to gauge if it is ready.
When it is ready, pour it out onto your board and scrape out the bucket and clean well before next using it, in fact, keep everything as clean as you can as you go so no contamination gets into the plaster and makes it go off faster or ruin your work as you do it.
Pull some wet plaster off the board onto your hawk and then, standing near one corner of the wall transfer the plaster to your trowel and begin spreading it up the wall in lines and work your way along to the other corner.
Then go back to the beginning and plaster above this until the whole wall is covered.
This is sometimes where beginners go wrong by not having put PVA on the wall and by being too fussy so the plaster dries too fast.
But if PVA has been applied and you don’t hang around then the plaster can be evened out all over until it is fairly smooth, but not perfect as that comes with the next coat.
The first coat can now be left to go off while the next mix is being made.
The second coat is usually put on slightly thicker than the first one but not so thick that it can’t be spread easily.
If too thick it will take a lot of effort to spread and may go off before a good finish can be achieved.
Flicking or spraying a small amount of water onto the plaster prolongs the drying out but is only used if the mix is put on too thick at this stage.
The second coat is applied much like the first coat and usually this coat takes longer to dry and so you will have more time to work it.
Once you’ve got it as good as you can, leave it, and wait for it to go off. This is a good time for a cup of tea and or clean the edges where the plaster has spread to the other walls which can be carefully scraped to leave the edges flat and square.
Finishing is where the last coat is made flat and smooth, but not too smooth or the paint and or paper will not stick. This is where the skill of the plasterer comes into play.
Not everyone can create a finish good enough for painting at their first try unless all steps have been followed and a bit of luck goes with them and so sometimes the wall won’t look so good and it gets sanded down after it has dried. This is not a good idea and is not worth the times it takes; but some small marks can be sanded out if necessary.
Having the right trowel helps enormously because a good plasterer’s trowel will have bevelled edges so it doesn’t dig in so much, be the right size and fit in the hand comfortably.
These trowels cost a bit more than normal ones but are worth it in the long run, unless you are going to just do the one off job and then a cheap throw-away one will do if you are not that bothered about getting a good finish.
A hawk can be made out of ply with a handle screwed into the middle for a one off job; but for anyone serious about plastering, having the right tools will be better in the long run so long as they’re kept clean and usable.
Trowelling up the finished work is a skill that has to be learnt from practice and is best done by watching a tradesman do it and then doing the same.
A reasonable finish can be achieved by trowelling the lines away, filling the troughs and levelling the bumps using a brush to flick some water onto the area being done and trowelled flat.
Keep doing this until the wall is flat and smooth, but don’t make it too smooth.
And then clean up everything before the plaster goes hard.
