Preparing your walls for painting is a crucial step that often determines the quality and longevity of your paint job, especially in regions with diverse environmental factors such as Auckland. A key aspect of this preparation is cleaning the walls effectively. Over time, walls accumulate dust, grime, and stains, which can interfere with the adhesion and appearance of fresh paint.

This guide will explore the best methods for thoroughly cleaning walls before you start your painting project. We’ll cover the importance of removing dirt and oils, the best cleaning solutions, and tips for tackling stubborn stains. Whether you’re a seasoned DIY enthusiast or a first-time painter, understanding how to clean your walls properly can make a significant difference in the outcome of your paint job, ensuring a smooth, clean, and vibrant finish.

How to Clean Walls Before Painting

Preparing your walls before exterior house painting in Auckland is a critical step in the process. It ensures the paint adheres properly and produces a smooth, professional finish. Here’s a detailed approach to cleaning your walls before painting:

  1. Give It a Good Basic Scrub Rinse For Interior WallsStart by giving your walls an essential scrub. Use a gentle detergent mixed with water and apply it with a sponge or soft cloth. This will remove most of the surface dirt and dust. After scrubbing, rinse the walls with clean water to remove any soap residue. Ensure the walls are completely dry before proceeding to the next steps.
  2. Remove Mold and MildewTreating these areas before painting is essential if you notice mould or mildew on your walls. Use a solution of bleach and water (one part bleach to three parts water) or a specialised mould removal product. Apply the solution to the affected areas, scrub gently, and rinse thoroughly. Remember to always wear protective gear, like gloves and a mask, when dealing with mould.
  3. A Chemical Clean for Exterior WallsYou may require a more robust chemical cleaner for tougher stains or grease spots on your walls. Most experts suggest using a degreaser or a trisodium phosphate (TSP) solution for these areas. Be sure to follow the safety instructions on the product label, as these cleaners can be quite potent.
  4. Sanding for a Smooth FinishSanding your walls can help achieve a smooth surface, which is ideal for painting. Use fine-grit sandpaper to gently sand down any rough spots, bumps, or previous drips of paint. This step is especially important if you paint over a glossy finish to help the new paint adhere better.
  5. Exterior PreparationFor exterior walls, the preparation might include more intensive cleaning due to increased exposure to outdoor elements. Power washing is common for exterior walls, effectively removing dirt, debris, and peeling paint. However, be cautious with the pressure setting to avoid damaging the wall surface, and be careful while painting the exterior of the house.

What to Clean Walls with Before Painting

When preparing to paint your interior or exterior walls, the key to a flawless finish is in the preparation, especially cleaning. Properly cleaned walls can enhance paint adhesion, ensuring a smooth, long-lasting finish. Here’s a guide on what to clean walls with before painting, focusing on popular products in New Zealand and eco-friendly options for external walls.

Internal Walls

For interior walls, cleanliness is crucial to prevent imperfections. Dust, grime, and oily spots can interfere with the paint’s ability to adhere properly to the wall. Two popular products in New Zealand for cleaning interior walls are Sugar Soap and Exit Mould.

Sugar Soap: This is a powerful cleaner, often available in a concentrated liquid or as pre-mixed wipes. It’s excellent for removing grease, dirt, and nicotine stains from walls before painting. To use, dilute the sugar soap as directed on the package, apply it to the walls with a sponge or cloth, and then rinse the walls with clean water. Ensure the walls are completely dry before painting.

Exit Mould: If you’re dealing with mould or mildew, especially in damp areas like bathrooms or kitchens, Exit Mould can be an effective solution. It’s designed to kill and remove mould spores, preventing their return. Spray the affected area, leave it for the time specified by the manufacturer, and then scrub and rinse it thoroughly. Remember to wear protective gloves and ensure good ventilation when using this product.

External Walls

External walls are exposed to more severe conditions and contaminants like pollution, mould, and mildew. Before painting, it’s essential to remove these elements to ensure the paint adheres well and lasts longer. Soft Chemical Wash and environmentally friendly chemicals are common choices in New Zealand.

Soft Chemical Wash: This method involves applying a gentle chemical solution to the external walls to break down and remove dirt, grime, and organic growth without damaging the underlying surface. It’s particularly effective for delicate surfaces or when you want to maintain the integrity of the original material. After applying the chemical solution, the walls are usually rinsed with a low-pressure water spray.

Environmentally Friendly Chemicals: These specially formulated products aim to minimise environmental impact. They are biodegradable and devoid of harsh chemicals, making them a safe choice for homes and the environment. When using these products, make sure to follow the manufacturer’s instructions for application and rinsing, and ensure that you remove all residues before painting.


Properly cleaning your walls before painting is a crucial step that can significantly impact the final result. Using the right cleaner, whether it’s a mild detergent solution for general cleaning or a more potent agent like TSP for tough stains, will ensure you flawlessly prep your walls for a new coat of paint. Remember, the time and effort spent on this preparatory step can lead to a more beautiful and long-lasting finish, elevating the overall appearance of your space.

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