Should You Sand & Clean Walls Before Painting?

Dec 27, 2023

Before embarking on any painting project, whether it's a small touch-up or a complete room makeover, one crucial step that often gets overlooked is cleaning the walls.

While it may seem like an unnecessary chore, taking the time to properly prepare your walls can greatly impact the outcome of your painting job. In this comprehensive guide, we'll delve into the importance of cleaning walls before painting and provide you with detailed instructions on how to do it effectively.

The Importance of Surface Preparation in Painting

When it comes to painting, whether it's the interior or exterior of a building, professional painters understand that the key to a long-lasting and high-quality finish is in the preparation. Surface preparation, which includes sanding and cleaning, is an essential step that should never be overlooked. In this post, we'll explore why professional painters take the time to sand and clean walls before painting and how it contributes to the overall success of a painting job.

The condition of your walls directly affects the quality and longevity of your paint job. Here are a few reasons why cleaning walls before painting is essential:

Improved Adhesion

Paint adheres better to clean, smooth surfaces. Dust, dirt, and grime can create a barrier between the paint and the wall, leading to poor adhesion and premature paint failure.

Even Application

Clean walls ensure that paint goes on smoothly and evenly, resulting in a professional-looking finish. Dirt and debris on the walls can cause paint to clump or streak, detracting from the overall appearance.

Prevention of Stains and Blemishes

Dust, grease, and other contaminants on the walls can cause unsightly stains to bleed through the paint over time. By thoroughly cleaning the walls beforehand, you can prevent these stains from ruining your paint job.

Longevity of the Paint Job

A clean surface allows the paint to bond securely to the walls, extending the lifespan of your paint job and reducing the need for frequent touch-ups or repainting.

The Cleaning Process: Step-by-Step Instructions

Now that we understand the importance of cleaning walls before painting, let's dive into the step-by-step process to ensure that your walls are thoroughly prepped and ready for a fresh coat of paint.

1. Gather Your Supplies

Before you begin, gather the necessary supplies:

Warm water
Mild dishwashing liquid soap
Soft cloths
Vacuum cleaner
TSP (trisodium phosphate), if needed

2. Dust and Remove Cobwebs

Start by using a broom to knock down any dust bunnies and cobwebs from the walls and ceiling. Pay special attention to corners and hard-to-reach areas where dust tends to accumulate.

3. Vacuum

Use a vacuum cleaner with a bristle attachment to vacuum any floor areas near the walls. This will help remove loose debris and prevent it from getting trapped in the paint.

4. Wash with Warm, Soapy Water

Fill a bucket with warm water and add a small amount of mild dishwashing liquid soap. Dip a sponge into the soapy water and gently scrub the walls, starting from the base and working your way up. Focus on areas with visible dirt, handprints, or grease buildup.

5. Rinse Thoroughly

After washing, rinse the walls immediately with clear water and a damp sponge to remove any soap residue. This will prevent streaks and soap buildup on the walls, ensuring a smooth finish for the paint.

6. Consider Using TSP for Tough Stains

If your walls have stubborn stains, grease, or oil buildup that cannot be removed with soap and water alone, consider using TSP (trisodium phosphate). TSP creates an alkaline cleaning solution that effectively dissolves greases and oils.

Follow the product label instructions for mixing the TSP with water and use a sponge to scrub the affected areas. Be sure to rinse the walls thoroughly with clean water afterward to remove any residue.

7. Protect Surfaces and Wear Gloves

When using TSP or any other cleaning solution, be mindful of protecting surfaces that won't be painted, such as wood floors or furniture, from stains or damage. Use drop cloths to cover floors and furniture, and wear rubber gloves to protect your skin from harsh chemicals.


In conclusion, sanding and cleaning walls before painting are non-negotiable steps in the professional painting process. These preparations are essential for repairing imperfections, enhancing paint adhesion, and achieving a uniform finish. By understanding the importance of these steps, homeowners can appreciate the value that professional painters bring to the table, ensuring that their investment in a painting project leads to beautiful and lasting results.

professional painter at work