How to Clean Walls Before Painting—and Why You Should Never Skip This Step

When preparing to paint a room in your home, you may overlook the first and most essential step: cleaning the walls. As it turns out, this step is crucial to the overall quality of your painting job—and it's also often skipped.

"Cleaning your walls before painting is critical for ensuring better paint adhesion, a smoother finish, and longer-lasting results," explains expert painter Tom Curren. Your walls have had plenty of time to accumulate dirt, especially in high-traffic areas where they collect fingerprints, dust, oils, and pet residue. "Without cleaning, these contaminants will act as a barrier between new paint and the wall surface," says Curren, "leading to premature peeling, streaking, bubbling, or uneven color."

Read on to learn how to get your walls into pristine shape before you even pick up a paintbrush.

Supplies You'll Need

Most people underestimate how much grime tends to build up on walls, especially in high-traffic areas. “Paint won’t properly stick to dust, grease, or even invisible residues of daily life,” says remodeling professional Lior Kahana.

Gather the following materials in preparation for cleaning your walls.

• Mild dish detergent
• Warm water
• Non-abrasive sponge
• Cleaning buckets (one for cleaning solution, one for rinsing)
• Drop cloths or plastic sheeting
• Microfiber duster or vacuum with brush attachment
• Step ladder
• Painters tape
• Microfiber towels
• Degreasing cleanser (optional)

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How to Clean Walls Before Painting

To thoroughly and efficiently clean your walls before the painting begins, follow these steps. 

1. Protect Your Space: Kahana advises covering the floor with a drop cloth and tape around trim, outlets, and switches to protect from moisture damage.
2. Remove Dust: Before introducing any moisture, it’s crucial to remove any loose surface dust, says Curren. Use a vacuum with a soft brush attachment or a long-handled microfiber duster to gently sweep the entire wall surface, starting from the top corners and moving downward. Pay particular attention to crown molding, corners, baseboards, and behind radiator vents, where cobwebs and dust tend to accumulate.
3. Mix Your Cleaning Solution: In a clean bucket, mix warm water with a small amount of mild dish soap (a few drops per gallon of water). Using a clean, non-abrasive sponge or soft cloth, dip into the soapy solution, being careful to wring out excess water to avoid over-saturation. “Don’t soak the wall—just dampen it,” cautions Kahana.
4. Scrub Walls: Gently scrub the walls in a circular motion, starting at the base of the wall and working your way up in manageable, vertical sections. “This prevents dirty water from dripping onto already-cleaned areas,” explains Curren.
5. Degrease Stubborn Stains: For high-use areas, like kitchens, bathrooms, or mudrooms, consider opting for a degreasing cleaner to tackle built-up grime and oils, advises Curren. Always make sure to read the instructions and remember to wear gloves to protect your hands. (Nitrile or rubber gloves are recommended.)
6. Rinse Well: When a full wall or section has been cleaned, rinse it thoroughly with clean water. Use a new sponge or cloth to wipe away any soap residue. Skipping this step can leave behind a film that interferes with primer or paint adhesion, warns Curren.
7. Blot and Air-Dry: Allow the walls to air-dry for several hours or overnight (depending on humidity levels) and use a clean, dry microfiber towel to blot any leftover moisture in the corners. "Don’t rush into painting," says Kahana. "Wait until the surface feels completely dry to the touch."

Tips and Tricks for a Cleaner Finish

To ensure your walls are properly prepared for painting, heed the following insider tips from our experts.

• Avoid cleaning in direct sunlight, especially on hot days, says Kahana. This can cause the walls to dry unevenly, leaving water streaks.
• Clean the ceiling and trim first. This way, when dust and debris fall, you won’t dirty up a previously cleaned surface, says Curren.
• For kitchen walls, Kahana recommends using a degreaser before sanding or priming. Additionally, any surface with signs of mold or mildew should be treated first with a vinegar solution.
• Never skip rinsing, as any leftover soap or cleaner can interfere with the proper setting of the paint. “Clean walls are the foundation of a good paint job,” says Kahana.
• If walls feel gritty to the touch after cleaning, or if there is visible leftover residue, Curren recommends a light sanding to help smooth the surface and ensure that the paint sticks evenly.