How to prepare your walls and ceilings for painting.
Why do you prepare walls and ceilings for painting?
The most obvious answer is that the walls need to be prepared to give an excellent finish. Also it allows for adhesion on previously painted surfaces. Read this post further to see how to prepare walls and ceilings for painting, the professional way.
Types of Sanders and glass paper grades.
Glass paper grades can go from 16 to 1000. I usually use anything between 80 and 120 for preparing walls and ceilings.
You have to take a judgement on how to prepare walls and ceilings for painting. This is usually done by looking down the side of a wall or ceiling to catch it in the light to see where the undulations and defects are.
With ceilings you literally have to crane your neck back and stare at it to see where the undulations are.Also with cracks what you must do with them is to make them bigger so use a tool like a scraper or a sharp knife to cut the cracks open to a V shape to allow the filler to adhere.
When I was an apprentice we had to rub everything down by hand, nowadays we can do everything with electric sanders. To control the mess with an electric sander you have to connect it to a dust extractor. This is worth it if you’re doing lots of decorating simply because of the cleanup time afterwards and health and safety issues around dust.
I prefer to use what’s known as a drywall sander for sanding walls and ceilings. This is quick and can be done from the floor without the need for steps. There are also some very good handheld sanders like Festool or Mirka. They also do a drywall type sander, although these can be expensive, but do the job very well.
Types of filler for walls and ceilings.
There are two types of filler for walls and ceilings. These are either ready mixed or fillers you have to mix with water. I usually stay away from ready mixed fillers unless they are a fine surface filler or such like.
For large areas of surface filling I use a drywall type filler. These come in either 5 kg or 10 kg bags. They can also come ready mixed but I have a tendency to stay away from that because with ready mixed fillers they can dry far too hard.
The filler I use is Gyproc Easi-Fill. I like it because it dries quick, is an excellent smooth finish and is easy to sand down.
If you have large areas of filling use a large 6 inch filling knife (Purdy do one) or a plasterers trowel. Mix up the filler and apply it to the undulations and cracks on your walls and ceilings.
This will be classed as your 1st fill.
Once your 1st fill is complete, sand down to a smooth finish and paint your ceilings and walls with a single coat of paint. The reason for this is that the first coat of paint will show up more areas of filling on your walls and ceilings. Don’t be disheartened, this is perfectly normal.
Once the first coat of paint is dry then apply your 2nd fill. You’ll find especially round cracks, that a second application of filler is required. You need to sand down again and touch up these 2nd filled areas with your chosen paint colour for your walls and ceilings.
If my 1st fill has gone well, I sometimes use a ready mixed lightweight filler for my second fill. This is also known as spackling filler in the USA. It’s ready mixed, very light inconsistency, dries quickly. It doesn’t sag or sump and has very little sanding down to do.
Once you’re happy with your second fill and touch ups, you’re ready to apply your final coat of paint.
Scrim tape for walls and ceilings.
Scrim tape is a very handy material to have. It is a large roll of tape in a style of a bandage which is sticky on one side. You simply apply the sticky side to cracks which helps to keep the crack together. Plasterers use this tape to bind two sheets of plasterboard together prior to plastering.
Once the tape has been stuck over the crack you need to do at least two fills over the top. Use a large 6 inch filling knife or plasterers trowel to give a wide fiil over the bandage. The first fill will show show the bandage still. Once dry, sand very slightly in order to lose the worst of any ridges, but not so hard in order to reveal more of the tape bandage.
There is no need to paint over at this point. Scrim tape will always need two fills. Apply your second fill using a wide 6-inch knife or plasterers trowel.
Treating damp and stains.
The prerequisite for treating damp and stains is to make sure that the source of damp or stains no longer exists. Once that has been established you are now able to treat the damp or stain.
If you try to paint over a water stain or damp with a water-based emulsion this will come through like it yellow stain. This needs to be treated with an oil-based damp and stain blocker.
Most damp and stains can be easily treated with old-fashioned oil based undercoat. This is a cheap option but cannot be painted over until the following day, due to the solvent drying time. This sometimes is inconvenient if you’re pressed for time.
These days I prefer to use Zinsser Cover Stain. This is an oil based stain blocker which dries within an hour and can be painted over the same day. There are many other damp and stain blockers again like Zinnser BIN, which is a methylated spirits (denatured alcohol) based blocker.
BIN is used for resinous type stains, but these are rarely found on walls and ceilings. I like to use the spray can version to quickly touch up stains which bleed through as its easy to apply and dries quickly.
Types of paint finishes for walls and ceilings.
There are usually three types of vinyl finishes. Matt, satin or silk.
Most people nowadays go for a matt type finish on their walls and ceilings, especially their ceilings. Matt finishes help to hide any bad areas on walls or ceilings.
If walls and ceilings have been newly plastered you will need to apply a mist coat. A mist coat is a watered down coat of paint in order to seal the new plastered area. Never apply a full coat of paint to a newly plastered area, especially if it has vinyl in it. This must be watered down.
Satin paints are usually an eggshell type finish. These paints have a slight sheen to them. these types of paints are usually used in kitchens and bathrooms in order to repel water and steam.
Silk paints are a bit old fashioned nowadays and these type of paints provide a full sheen to your walls and ceilings. Silk paints can give you all sorts of trouble. My advice is to stay away from them. They dry like a full skin of paint and if your walls are not prepared correctly you have dust on them you can simply peel the paint away. Stay away would be my advice.
Lining walls and ceilings with lining paper.
If your walls and ceilings are particularly bad you can always line your walls and ceilings with lining paper. Lining ceilings can be particularly difficult and takes a bit of practice. You will still need to go through your first and second fill process regardless, prior to any lining.
The purpose of lining walls and ceilings is to give you an excellent, clean surface to paint over. It also helps to hide bad areas and undulations.
If my filled walls and ceilings was 50% covered in filler I would seriously think about lining the walls and ceilings. To have this much filler on walls and ceilings would tell me the walls and ceilings are in bad condition and therefore lining would help.
After you have gone through the second filled process, you would need to seal the walls prior to lining paper being applied. In the UK we call this process sizing. Sizing is basically watered-down paste which is then applied over the wall or ceiling to apply a sealer coat.
I would recommend using a ready mixed tub paste to apply the lining paper to the walls and ceilings. The reason for this adhesion is much better than traditional flake paste.
This is how I prepare walls and ceilings for painting. Stick to the information in this post and you won’t go far wrong.