Why Preparing Walls Before Painting Matters
The best results start long before the first coat goes on. Skipping proper prep can lead to cracks showing through, paint that won’t adhere, or dark patches that bleed through the top coat. Preparing walls properly makes it easier for your chosen paint colour to cover evenly and means fewer coats are needed.
Proper preparation:
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Helps paint stick better to the surface
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Reduces the risk of bubbling or flaking
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Creates a smoother finish with better coverage
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Extends the life of your paint on interior walls
Once major cracks or damage are repaired, the rest of the wall surface can be addressed with a basecoat or filler to ensure a uniform finish.
Assessing the Wall Condition
Before you start painting, take time to thoroughly assess all the walls in your room. Look closely for any peeling paint, cracks, or holes that need to be filled before you can achieve a professional finish. Pay special attention to areas that might have suffered from dampness or water damage, as these can affect how well your chosen paint adheres to the surface. Run your hand over the walls to check for any rough patches or uneven finish that could show through your new interior paint. Make a note of the chosen paint colour and the type of interior paint you plan to use, as this can influence how you prepare the walls for painting. By carefully inspecting every wall and identifying any issues early, you’ll ensure your surfaces are properly prepared and ready for a flawless coat of paint.
Cleaning the Walls
Start by clearing the room. Remove wallpaper if needed, shift remaining furniture away from the walls, and cover floors and skirting boards with dust sheets. Wipe the surface using warm soapy water or a warm sugar soap solution to remove dust, grease, and stains. For safety, wear gloves and protective eyewear when using cleaning agents like sugar soap. After cleaning, open a window to ventilate the room and help remove fumes or moisture. Use a damp sponge to rinse the walls and allow them to dry fully before moving on.
If there’s old wallpaper, use a stripping knife to peel it back gently. Check for signs of mould or mildew, especially near the ceiling or corners, and treat the area using Promain’s Centrecoat GS36 Fungicidal Wash to clean the surface and prevent further growth.
Removing Old Wallpaper
If your walls are covered with old wallpaper, removing it is a crucial step in preparing walls for painting. Use a stripping knife to gently lift and scrape away the wallpaper, taking care not to damage the wall surface underneath. Once the wallpaper is removed, use a damp sponge to wipe away any remaining adhesive or debris, ensuring the surface is clean and smooth. After cleaning, allow the walls to dry completely. To create the perfect base for your chosen paint, apply a mist coat to the freshly stripped walls. This will help seal the surface and provide a smooth foundation for your first coat of paint, ensuring a more even and lasting finish.
Fill and Repair
Check for cracks, small holes or damaged plaster. Use a filling knife and quality filler like Planitop Smooth and Repair to fill holes and cracks. Allow the filler to set, then sand it back using fine sandpaper to get a smooth surface. Repeat the process for deeper marks or gaps.
For flexible joints, like where two walls meet or around door frames, use Elastofill Acrylic Jointing Compound for a durable seal that prevents cracks from reappearing.
Sanding and Smoothing
After filling and patching, lightly sand the entire wall using fine sandpaper. This helps remove small imperfections and rough patches. Wipe the dust away using a clean damp cloth. It is crucial to let the walls dry completely before proceeding to painting to ensure optimal paint adhesion and a smooth finish. Walls must be completely clean and dry before applying any paint.
New plaster needs extra attention. Allow the walls to dry fully until all dark patches disappear. Once dry, apply a mist coat made from watered-down water based paints to seal the surface. This helps the first coat of your chosen paint colour go on evenly and stops the new plaster soaking it all up.
Using the Right Tools
Having the right tools on hand makes preparing walls for painting much easier and helps you achieve a smoother finish. Invest in a quality paint roller and extension pole to cover all areas of the walls and ceilings efficiently. Use a filling knife to fill holes and cracks, and fine sandpaper to smooth out any imperfections on the surface. Run masking tape along the edges of the walls, ceilings, skirting boards, and around light fixtures to protect them from stray paint. For detailed work, use a brush to apply paint to the edges and corners, and to cut in around tricky areas. With the right combination of rollers, brushes, filling knives, and masking tape, you’ll be able to fill, smooth, and protect every surface, making the painting process much more straightforward.
Masking and Protecting
Run masking tape along skirting boards, sockets, light fixtures, and carefully along every edge you want to keep clean to ensure crisp paint lines and a professional finish. Cover floors and remaining furniture with dust sheets. Removing or covering anything that can get splashed saves time later.
Working with New Plaster
Painting new plaster requires a few extra steps to ensure a perfect finish. First, allow the new plaster to dry completely - wait until the surface is free from dark patches and feels dry to the touch. Once dry, clean the plaster with a sugar soap solution to remove any dirt or dust that could affect the paint’s adhesion. Next, apply a mist coat made from watered-down paint to seal the surface and create a smooth base for your chosen paint. After the mist coat has dried, apply your first coat of paint, making sure to let it dry fully before adding a second coat. Using two coats of paint on new plaster will help you achieve a durable, even finish that looks great and lasts longer.
Priming the Wall
Before the first coat of interior paint, especially on repaired areas or porous plaster, it's a good idea to apply a primer. This helps paint adhere better and gives you a more even finish. If you’re painting over old stains or mould-prone areas, add Centrecoat R155 Fungicidal Paint Additive to your paint to protect the wall long term.
For external or damp walls, treat them with Keim Algicid first to stop algae or fungal growth before painting.
Painting Your Interior Walls
Once the surface is ready, apply the paint using a quality brush or paint roller. Always start from the top and work down. Two coats are usually enough, but prepping properly helps avoid needing extra layers.
For best results, paint windows in the morning to allow them to dry properly, and pay special attention to painting around windows for a neat, professional finish.
Start with your mist coat if you’re painting over new plaster. Then apply your first coat of your chosen paint. Let it dry as recommended before applying the second. Allow each coat to dry fully between applications for the best finish.
Product Recommendations from Promain
Promain offers reliable products to support each step of preparing your walls:
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Centrecoat GS36 Fungicidal Wash - Removes mould, algae and mildew before painting to improve wall hygiene and appearance.
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Centrecoat R155 Fungicidal Paint Additive - Mix with paint to protect painted walls from future fungal growth.
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Keim Algicid - A biocidal wash used as a pre-treatment to stop mould and algae on walls before painting.
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Planitop Smooth and Repair - Ideal for patching cracks and smoothing walls ready for paint.
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Elastofill Acrylic Jointing Compound - Seals joints and flexible areas to prevent cracking and movement under paint.
Get the Right Products from Promain
Whatever condition your walls are in, Promain has the tools and products to help. From fillers to fungicidal washes and additives, we stock everything you need to get a cleaner surface and better finish. Visit Promain to find everything required for proper wall preparation.
Frequently Asked Questions
How do I prepare interior walls before painting?
Clean the surface with sugar soap or soapy water, remove wallpaper, fill holes, sand smooth, apply a mist coat (if needed), and prime where necessary.
How do I stop peeling paint on interior walls?
Peeling paint often means poor prep. Strip off loose paint, clean thoroughly, repair cracks, then sand and repaint with two coats of quality paint.
How can I avoid an uneven finish?
Always fill and sand properly, apply paint evenly with a roller or brush, and allow full drying time between coats.
Do I need to prime walls after filling holes?
Yes, filler is porous. Prime over filled areas to stop the paint soaking in and leaving patchy spots.
Can I paint over new plaster straight away?
No, let the plaster dry until there are no dark patches, then apply a mist coat before painting.