If you are considering painting a room, there are several steps that you must take before you begin painting. It is important to clean, sand, and prime each wall before you ever dip your brush into the paint.
One of the most important first steps is sanding the walls. This article will explain the importance of this process and give tips on exactly how to do it.
Sanding walls is suggested for most plaster walls and is especially suggested for interior walls that have spackle, bumps, flaws, or old coats of paint or primer.
Painting your exterior & interior walls smoothes the wall surface, which helps the paint stick and makes the final product more aesthetically pleasing.
How Do You Smooth Out a Bumpy Wall?
Smoothing out a bumpy wall is most effectively done through sanding. We will explain how to choose your fine grit sandpaper, clean the wall, and smooth surface.
Common walls that require sanding are plaster walls, textured walls, concrete walls, and previously painted walls. This is because these materials are often bumpy or uneven and paint does not stick well.
How To Sand Walls Before Painting: A Professionals Guide
1. Choosing The Right Sandpaper
Discuss the best types of sandpaper to use when sanding walls. Are different types better for different stages? (Such as for sanding in between coats of paint job).
Explain the most important specs to look at when buying fine grit sandpaper, such as the size, the grit, etc.
In order to ensure that you properly smooth out any bumps, flaws, or small dents in a wall, it is important to use the fine grit sandpaper. Sandpaper comes in different sizes and grits, which determines how coarse the paper is.
There are several levels of grits, and knowing which to choose when sanding a wall is an important part of the process. Sandpaper that you can find at the hardware store usually ranges from 60 - 80 grit, 100 - 150 grit, and 180 - 220 grit. The higher the grit, the finer the action. The coarsest sandpaper is best for removing previous finishes.
When smoothing out drywall, we recommend a medium-grit sandpaper that won’t clog. Grits 100 and below are too coarse and will scratch or ruin the drywall. These scratches will be visible under paint, so we recommend using grits between 120 and 150.
When sanding walls that have been previously painted with water-based paint, we recommend a finer grit sandpaper. Consider using a grit between 180 and 220. For walls that have been previously painted with oil-based paint, we suggest a medium grit sandpaper. Somewhere between 100 and 150 grit is the ideal range for this project.

2. Preparing & Sanding The Walls
3. How to Clean Walls After Sanding
Sanding creates a large amount of dust, which can cause bumps and other imperfections if painted over. To avoid this, clean the wall after you sand this.
Wet a small towel or damp cloth and ring it out so that it is slightly damp.
Working your way from top to bottom, gently wipe the wall to get rid of any dust with damp cloth that sanding caused.
Make sure the wall is dry completely before applying primer or paint or joint compound.
What Happens If You Don’t Sand Walls Before Painting?
Sanding walls before starting the painting avoids many problems. First and foremost, walls that are not sanded do not hold paint or joint compound well. Paint or joint compound can chip easier and often lasts only several years.
It avoids ugly bumps and raised spots on the wall and makes for a more uniform look. Additionally, brushes that apply primer often leave fibers, and sanding is the most effective way to eliminate these fibers for a clean wall and look.

Different Types of Sanding Tools & Equipment
There are plenty of tools on the market that exist to help you sand your walls. From belt sanders to drywall sanders, we will cover the most common and most effective tools so you can best choose which one works the best for your project.
Sanding Walls Before Painting FAQs
Do professional painters clean walls before painting?
Yes. Professionals absolutely clean walls before applying painting. It is necessary to get any film, dirt, or debris off a wall surface because anything left will get caught under the paint job and can cause bumps or imperfections instead of top notch job.
Do professional painters sand walls?
Yes. Professional painters sand walls before painting because it leaves a smoother, more aesthetically pleasing and professional look top notch job.
How do you sand inside without making a mess?
To sand inside the home without making a mess we recommend using tools with automatic dust catchers, or vacuums that dust as you go. These options tend to be pricier, and we suggest that no matter what option you choose, you wear a mask, goggles, and head covering.
Conclusion
Sanding is an important part of the painting process that should not be ignored. Creating flat, even surfaces before painting a wall ensures a professional look and helps the paint stick long term.
Take a tip from the pros and make sure to properly prepare your walls before painting them. This may take extra time, but it is more than worth the effort if you want clean, smooth-looking walls and paint that doesn’t chip after a few years!