Ask any painter what the secret to a beautiful interior paint job is and you will usually get an answer along the lines of prep work.
I typically tell my clients that the keys to a great paint job are prep work and that painting is 80% prep work and 20% painting.
This holds true for exterior painting, kitchen cabinet painting, and interior wall painting.
Speaking specifically about interior wall painting, cleaning your walls before painting is an extremely important part of your prep work that cannot be skipped.
But what do I mean by cleaning? Do your walls needs to be scrubbed with soap and water? Cleaned with TSP? Simply dusted with a broom or shop vac?
Well… It depends.
Each project is different and requires a different level of wall cleaning before you apply your paint.
In this post I am going to cover a few different interior wall painting scenarios and how to clean your walls before painting for each different project.
- How to clean already painted walls
- How to clean greasy kitchen walls
- How to clean smoke stained walls before painting
- How to clean new drywall before painting
- How to clean moldy walls before painting
How To Clean and Prep Already Painted Walls (In Good Condition)
These are the walls that you are most often going to run into. They aren’t greasy, not overly dirty and have no major stains on them.
Do they even need to be cleaned at all?
Yes, every wall should get some level of cleaning before you apply new paint. It’s not that the new paint will fail, but rather that by cleaning the wall you are giving the new paint the best possible surface to live on and create a smooth and beautiful finish.
For these walls I like to run over the entire walls with a round sanding disc and pole. This is simply to knock off any imperfections in the old finish, smooth it, and prepare it to adhere to the new finish.
I use a round sanding disc (the Radius 360 Sander) because it is the easiest to work with. rectangular sanding poles tend to flip over when using them and gouge your walls creating extra work. The round disc, along with a 2-4′ extension pole is quick and easy to use.
After sanding the walls, simply wipe them down with a slightly damp rag to remove any dust, debris, and spider webs.
How To Clean Greasy Kitchen Walls Before Painting
Kitchen walls typically require a bit more cleaning and prep work before painting than other walls.
Due to all the cooking going on in kitchens, they often have a bit of a grease and grime buildup.
If left as is, this can cause adhesion issues when applying new paint over the old paint. These areas can easily peel in the future, wear off easily if rubbed and even cause new paint to bead when applying.
You can’t jump straight to sanding these walls with a sanding disc either. The grease residue will clog up your sanding paper almost immediately. Instead, you need to clean off the grease before sanding.
On the internet, you will mostly see people recommending using a solution of TSP and water to clean greasy walls before painting. This works perfectly fine and I’m not against it at all. There are some things to be aware of when using TSP however, so make sure to use protection.
Instead of TSP, I like to clean my walls with a simple solution of warm water and Dawn soap (or any dish soap). Dawn is available anywhere and many homes already have it on hand, making it easier than TSP. It breaks down grease and leaves your walls incredibly clean.
Simply wipe down all your walls with the warm soapy water. Then, go back over the walls with clean warm water to rise off the soapy reside.
Allow your walls to dry 100%, usually a couple of hours (or speed it up with a fan), then sand your walls with a pole sander as mentioned above, wipe off the dust and you’re ready to paint.
How To Clean Smoke Stained Walls Before Painting
I’ve been in many homes with smoke stained walls either from smokers, fireplaces or just burnt cooking in the kitchen.
Smoke needs to be cleaned up and properly sealed before painting if you want to completely eliminate the smell and prevent the smoke from bleeding through your paint into your new paint.
While there are many different thoughts on how to best clean smoke, I’ve had the best luck with Arm and Hammer’s Cleaning Soda.
Cleaning soda (sodium carbonate) will help clean and remove the smoke and the smoke smell.
Simply mix the cleaning soda with warm water and scrub down the walls with a rag.
To rinse the walls, mix a cup a vinegar with a gallon of warm water and wash the walls again. This will neutralize the washing soda and help kill the smoke smell (and disinfect the walls).
Once the walls dry, sand the walls using a pole and disc sander as mentioned above. Wipe off the dust and you’re ready to paint.
NOTE: If your walls have really bad smoke stains, you may need to prime the walls to seal the smoke stain and prevent bleedthrough. I recommend Killz Max for this.
How To Clean New Drywall Before Painting
If you’re going to be painting new drywall, you’ll want to make sure to clean it off before painting as well.
New drywall won’t have any stains, smoke or grease to worry about, but instead, it’s going to be incredibly dusty from sanding the joints.
Excessive drywall dust on your walls can create adhesion problems for new paint and cause rough imperfections in your finished walls.
For new drywall, I like to take a shop vac along with a wide floor brush attachment and vacuum the dust right off the walls.
How To Clean Moldy Walls Before Painting
Moldy walls require a different level of cleaning before painting. I’ve written an entire post on cleaning and priming moldy walls that you can check out for more information on this topic.
Wrapping It All Up
Remember, a great painting job is 80% prep work and 20% painting. If you take the extra time to clean your walls before, you’ll end up with a better looking finished product that will last for years.
Wednesday 25th of May 2022
Hello ! When you say arm and hammer cleaning soda is it the “laundry” soda ?
Friday 9th of April 2021
What is the best grit for painted walls? Is it the same grit to use on drywall? Thank you for this website.
Monday 12th of April 2021
Hi Leslie, If I am sanding walls before painting, I like to use 120 grit paper on a round sanding pole. If I am sanding in between top coats, then I'll go up to 150 - 220 grit. Hope this helps. Good Luck!
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Tuesday 30th of July 2019
Awesome process. I love this article.
Thursday 27th of June 2019
Hello Ryan, My name is Sam and 3 of my friends and I are starting a painting company this summer. We plan on taking this very seriously and are currently doing market research and planning out our business. I would love if I could get in touch with you and discuss how to create a profitable and stable painting company. Thank you for your time and I hope this post gets to you! - Sam
Wednesday 7th of August 2019
Hey Sam, Best of luck with your new painting company. Feel free to reach out any time with questions. You can email me at [email protected]