A Guide on How to Clean Walls Before Painting

Updated: Oct. 30, 2023

Get your interior painting project off on the right foot by washing walls before painting them. Learn when this is a good idea and how a pro would do it.

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When repainting, most of the walls in your home will not require washing according to professional painter, Eric Regan, of Mission Painting & Home Improvements in Overland Park, Kansas. For the walls that should be washed, however, it is a critical part of the process.

Tools Required

  • 2-Gallon pail
  • Bucket
  • Drop cloth
  • Fans
  • Paint scraper
  • Putty knife
  • Razor blades
  • Sponge
  • Vacuum

Materials Required

  • Mild soap
  • Painter's tape
  • Plastic film
  • TSP substitute
  • Warm water

In kitchens (maybe hallways if you have children) where a fine layer of grease often coats the walls, bathrooms where hair spray may settle and in homes regularly exposed to cigarette smoke (nicotine can be seen as a streaky, yellow veneer), failure to wash these residues off the walls as your first step leads to major problems down the line. A cracked and curled topcoat requires the skill of a professional painter to repair, and Regan says it will likely cost you three times more than what you would have paid for the original job.

As a last consideration, sanding creates dust that can travel throughout a home, and for a small project, washing may be preferable to dust control for a DIYer.

Wash the Walls First

Plan to wash your walls before any other prep work. When considering the potential success of your painting project, grimy substances can affect adhesion of wall-repair materials as well as paint. So start with the washing step, then fix the nicks and dings. Don’t forget to check out these tips for painting plaster walls.

Project step-by-step (5)

Step 1

Clear the Wall

furniture Stokkete/Shutterstock

Remove any hardware stuck into the wall and use a razor blade to scrape away any tape or adhesive you find. Clear furniture away from your workspace and cover with a sheet of thin plastic film. No matter your experience level, compiling these 30 best painting tools and gadgets will prepare you to tackle any painting job at any time.

Step 2

Wash the Wall

bucket SHUBIN.INFO/Shutterstock

Fill a 2-gal. bucket half full of warm water and add a squirt of a mild, nonabrasive soap or TSP substitute according to its directions. Dip a large sponge into the soapy water and squeeze out the excess water until the sponge is moist but not wet. Regan compares this to preparing the sponge to wipe fingerprints off the refrigerator, rather than soaking the sponge as you would when washing a car.

Wipe down the wall with the sponge, rinsing and wringing it out frequently. Avoid excessive scrubbing, water from the sponge running down the wall and exposing the wall to too much moisture. These conditions can damage the wall.

Step 3

Wipe Away the Soap

Sponge Kryuchka Yaroslav/Shutterstock

Empty the bucket of dirty water. Rinse out the bucket, then refill halfway with fresh, warm water. Clean out the sponge in the sink, then use it to wipe the wall lightly, as before to remove any soap residue. Another great cleaning tip to consider ahead of time is how to clean paint rollers and trays, so you can save time and money!

Step 4

Dry Thoroughly


Before moving on to repair and priming, allow the wall to dry. Trapping moisture in the wall prevents paint from setting as well as opens the possibility for mold growth. Set fans to keep air in the room moving and break for the day.

Step 5

Final Caveats

primerBenjamin Clapp/Shutterstock

Although washing is necessary to the process, you cannot move directly from washing to topcoat in the case of grease, hairspray and nicotine. These substances must all be sealed with a coat of primer to accept today’s low-VOC latex paints. In the case of nicotine, Regan stresses use of an alcohol-based primer to address the smell and staining. Failure to prime often leads to hiring a pro to skim coat the walls and repaint, which is far more costly than a gallon or two of primer.

And now that you’ve prepared your walls, consider these¬†10 tried-and-true interior wall paint colors that are guaranteed to make your room look great.

Learn more about our expert Eric Regan here.

Plus, check out the best-kept secrets of professional painters in the following video: