How to Prep Walls for Painting

Aug 5, 2023 | Home Improvement

How to Prep Walls for Painting: Painting walls can be a very effective way to transform the look and feel of a space. Lighter colors can give the impression of fresh, airy spaciousness, while darker colors can feel rich and intimate. 

The right shade can tie all your fittings and furnishings together and create a pleasing relationship with outdoor spaces seen through windows and glass doors. Even touching up your walls in the same color can completely refresh any room.

There are numerous paint types and finishes, from matte to silk to eggshell to high sheen. Many paints are purpose-designed, with some having anti-scuff properties. At the same time, others are water-resistant and eco-friendly, solvent-free, and even anti-allergenic varieties.

Painting the walls in your home is usually straightforward, but you must make sure they are well-prepped first. In this article, Property Solvers over in the UK explore techniques for wall preparation that will achieve the best results and see your paint go further.

What You’ll Need for Wall Prep

You must approach a painting project with the correct equipment for the best results. Depending on the current condition of your walls, you may need:

  • Primer/undercoat for raw plaster
  • Sugar soap*
  • Gloves
  • Sponges
  • A mask
  • A wallpaper-stripping knife
  • A wallpaper steamer
  • Wallpaper stripping solution
  • Flexible filler
  • Emulsion and water create a “mist coat.”*
  • A paintbrush for “cutting in”
  • A roller and paint tray for covering larger surfaces
  • Enough paint to complete the required number of layers stipulated by the brand

Check the sections below to select the right tools and equipment for your project.

Prepping Newly Plastered Walls

How to Prep Walls for Painting – Plastered Walls

If you’re painting onto fresh, unpainted plaster, you’ll first need to check that it is dry. It’s important to note that plaster can take up to four weeks to dry thoroughly, and painting on plaster that is still damp may result in cracking or an uneven finish.

Dry plaster should be an even shade with no darker patches.

When painting directly onto the wall, your first step should be to brush on a primer coat to seal the surface. If you don’t, the plaster will suck the moisture out of the paint, and you’ll need to use more than you would otherwise be necessary.

We highly recommend the application of an undercoat – or “mist coat” – before you go in with your chosen paint color. A mis coat is a layer of thinned-down emulsion paint, usually made up of one part water to three parts paint.

Once your mist coat is dry, you should “cut in” around all edges and corners to give a sharp, neat finish. Now you can apply your final paint color to your walls.

Please note that after you’ve sealed your walls, you may choose to use lining paper, which will give your walls a smoother finish, hiding imperfections. It will also provide that little extra touch of insulation. However, you will be able to paint without taking this step.

Prepping Walls that Are Already Painted

How to Prep Walls for Painting – Already Painted Walls

Should the walls of your house already be painted, you’ll need to prepare them before rolling on a new color.

First, you’ll need to clean cracks and rough surfaces using sugar soap, as this will remove dust, dirt, and paint flakes.

Next, you’ll need to use filler to smooth over any holes or gaps. Flexible filler is always best, as it will expand and contract with its surrounding surfaces and will be less likely to crack.

It may be that your walls are already in great shape, with no notable flaking, unevenness, or patches of old wallpaper. Whatever their condition, we still highly recommend sanding each surface with fine grit paper to ensure that the new paint adheres as well as possible.

Before painting, clean the walls again with sugar soap, water, and a sponge.

Prepping Wallpapered Walls

How to Prep Walls for Painting – Wallpaper Removal

Suppose you wish to paint a surface that has been wallpapered. In that case, you should first remove the wallpaper with either a wallpaper steamer and a stripping knife or with a specialist wallpaper stripping liquid.*

You may find that the paper comes off just by scoring it diagonally with the knife tool, then soaking it with sponges of hot water and scraping it off (taking great care around electrical outlets. However, a steamer or stripping solution is likely to be more effective.

Be careful to control the angle of your knife as you go so as not to gouge the plaster below while you work.

Wait for the walls to dry, sand off any last flecks of wallpaper, then clean with sugar soap.

It may be that the walls underneath the paper have cracks or holes. If so, simply follow the instructions above for “walls that are already painted”: cleaning cracks, applying flexible filler, and sanding before finishing with more sugar soap. 

For Your Safety

Before you attempt to paint or clean around sockets or switches, you should consider turning off the power to these outlets at your consumer unit. This is particularly important if you believe you may remove these fixtures from the wall at any point.

It is a good idea to wear a mask when stripping wallpaper to avoid breathing in dust or fumes.

If you’re painting skirting or around windows, you should protect your flooring and window boards. Your surroundings should also be brushed down or vacuumed first so no dust or debris transfers to the paint.

The instructions above should help you to prime your walls in readiness for a flawless paint job. You may find that preparations are easier or more challenging depending on the age or history of your home. Sometimes, the process can even differ from room to room.

The more experience you have in preparing and painting walls, the more likely you will develop a strong technique and grow in confidence.

We hope the above guidance makes your next project feel slick and easy. All the best for your home makeover!

* Important Notes

  1. Sugar soap’s effectiveness in removing dust, dirt, and paint flakes. While sugar soap is known to be an effective cleaner, its specific effectiveness for each use case mentioned may be subject to variation.
    1. When in doubt, consult a professional.
  2. Specifics of the “mist coat” ratio. The “one part water to three parts paint” ratio might be standard. Still, it could vary based on the specific type of paint or the manufacturer’s recommendations.
    1. When in doubt, consult a professional.
  3. The process of removing wallpaper and the effectiveness of the described techniques. The mentioned methods (steam or soaking) are standard. Still, their effectiveness can be contingent on the type of wallpaper, its age, and the adhesive used.
    1. When in doubt, consult a professional.
  4. Generalization of preparation steps. The article makes several broad recommendations that might not apply universally to all types of walls or paints. For the most precise advice, referring to specific product recommendations or consulting with a painting professional like Robinson Painting of Colorado, LLC would be beneficial.


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