Before painting on walls preparation is essential for having your new ideas come to life.
Even if you have the best paint sprayer, you need to clean the walls and prepare them before you paint the wall, for the final result to look as polished as a professional’s job.
This is especially important if you plan on renting a paint sprayer, as they’re not cheap to rent by the day and you will want to get straight onto the wall painting and not have the spray gun sitting idle.
Aside from having to wash walls before painting (this also goes for exterior walls), there is some additional preparation needed especially if you are using a paint sprayer.
This is because the techniques when using a paint sprayer is quite different from when you are using the basic brush and roller (learn more about paint sprayers vs roller).
We’ve got a whole post dedicated to paint sprayer accessories which can save you a lot of time that we recommend you check out before starting work
Ready to transform your room quickly with a spray gun? Here is all you need to know about how to prep walls for painting, whether you are using oil-based or water-based paint the process is the same.
How to Prepare Walls for Painting
Once you have gathered all the tools and equipment you will need to remove everything else from the room and if it cannot be moved you will need to ensure it is completely covered.
Cover all the furniture that you cannot move with dust sheets to protect them.
Don’t forget to take down the curtains and blinds. These are the most likely to catch paint splatters and overspray, especially with more powerful sprayers such as airless paint sprayers.
Cleaning Walls for Painting
Once the room is cleared and the remaining furniture covered, you can start to clean and prepare the walls for painting. Properly cleaning the surface helps the coating adhere better and avoids ugly bumps and streaks from dust and dirt.
Note: the walls painting is not the same when redecorating popcorn ceilings. We have a separate post that covers how to paint popcorn ceiling in more depth.
The first step is to lay down drop cloths to protect the flooring from paint stains, this can be with canvas drop cloths, plastic drop cloths are also available but are not quite so good underfoot. Second, give them a quick dust, down unless you have a very high ceiling, you can do this without the right type of ladder by using a duster with a long handle.
The next step, before painting of walls, can begin, is to wash them down, the best cleaning agent we recommend using is sugar soap because it can get rid of old stains and marks. This is very important for kitchen walls as they may well have a fine layer of grease that you may not even realize is on them.
When washing the walls or your room, make sure that you are not using a soaking wet rag or sponge. The rag or sponge should be moist but not so wet that the water comes dripping down the wall because this can damage the wall and also this will slow you down as you will then need to wait for it to dry again.
Let the cleaning agent soak in for a few minutes before wiping it away again with a new clean moist cloth.
Again, remember not to have the water dripping down.
If the wall is still in excellent condition, you can start straight after it has dried. However, if there are any cracks or bumps now is the time to sort them out.
If the stains are severe and the sugar soap did not remove them for you then use a base coat before spraying with the top coating of latex paint, as they may well show through causing you to have to give the walls two coatings.
Filling Cracks and Sanding Down Interior Walls
The wall surface makes a lot of difference in how well the coating adheres and how even the color is. This is why it is important to fill in cracks and remove raised surfaces.
Filling in cracks is not as difficult, first thing is to sand away any loose plaster or paint away with fine-grit sandpaper, you may find a sanding block is handy for this, to get a smooth surface around and in the crack.
You can easily purchase wall fillers, the easiest type is a ready-mixed joint compound where it is a simple matter of squeezing the joint compound out of a tube or getting it out of the tub, but again there is an alternative, you can buy the powder and mix it yourself by adding water.
Whichever you decide on, once you have a smooth surface, ensure that the area is once again dust free before you spread it evenly over the crack with either a filler or putty knife and let it dry.
Make sure that the filler creates a surface that is as flat as possible and fills the hole or crack completely, larger holes may need this done twice, as the filler can shrink back if it is put on too thick.
For a more precise method, have the joint compound slightly raised above the plaster so that you can sand it down evenly once it has dried.
It’s best to use a filler or putty knife or to spread the goop because it lets you make sharp cuts and push it down to be more compact. A compact filling is important because you don’t want it to crumble nor push out of the crack.
Once all the cracks are filled, get to gently sanding down the walls before painting, you can opt for not sanding them but the slightly rough surface helps the paint adhere better and this will also remove any unwanted blemishes that will stand out once the paint is applied.
Last Steps Before Painting
When you’ve finished with the cleaning, filling, and sanding, you can start on the final preparations for painting the interior walls of your room. These last steps are safety measures to prevent paint drips or overspray on anything.
Cover all the furniture you haven’t covered with dust sheets yet and do the same to the floor. If necessary, you can tape the sheets together with masking tape or painters tape.
Mask off all the switches, fittings, door handles, sockets, and woodwork that won’t be painted with painters tape Don’t forget to cover the ceiling light as well and remove the shade if possible.
You may want to replace the masking tape after each layer of coating you apply to prevent the splatters from hardening on the masking tape, this is especially important if you are using normal masking tape and not using a painter’s tape, while spraying a water-based paint, as hardened paint can make it difficult to remove the masking tape which in turn can damage the new coat you just applied.
If you plan on using exterior paint inside, you need to ensure you have more than enough ventilation in the entire house as they can give off toxic fumes.
Once you’ve followed these steps you can bring out the spray gun. Make sure that all windows and doors are completely shut because any wind or draft can affect how the coating spreads.
Frequently Asked Questions
Here are some answers to popular questions.
Do you need to wash the walls before painting?
You do really need to wash the walls before painting them, this can be done quite easily with a damp sponge and mild detergent water solution. This is especially important if you are painting kitchen walls as there can be built-up grime and grease.
Can I use Dawn to wash walls before painting?
If you mix an ounce of Dawn dish detergent per gallon of warm water it should help to remove most dirt and smudges from your paintwork.
Do you need to wash walls after sanding before painting?
Yes, it’s always a good idea to wash walls after painting to remove all the dust particles from the walls. The sooner you do it the better as the dust that’s settled on the walls will slowly be blown around the house.