What to Clean Walls With Before Painting: Mistakes To Avoid

Before you paint, you need to clean your walls, even if they “look fine.” A simple mix of warm water and mild dish soap removes dust, grease, and residue. For tougher grime, use sugar soap or TSP, then rinse thoroughly and let everything dry before the first coat goes on.

Here’s a quick breakdown of what works best and when:

• ✅ Dish soap + water: Best for light dust and general cleaning

• ✅ Sugar soap: Cuts through grease, fingerprints, and kitchen grime

• ✅ TSP: Heavy-duty cleaner for smoke stains or glossy finishes

• ✅ Degreasers: Ideal for bathrooms, laundry rooms, and cooking areas

• ✅ Magic Erasers & mops: Helpful for high walls or scuff removal, just use carefully

At ProSmart Painting, we never paint over dirty walls. We assess the surface, clean it right, and make sure your paint actually lasts. That’s how we deliver finishes that hold up in real homes, not just on day one.

Keep reading to learn what to clean with, what to avoid, and how to prep like a pro, before the brush even touches the wall.

The Best Products to Clean Walls Before Painting

Not every wall is the same, and neither are cleaning products. Some are great for light dust, while others tackle deep grime and kitchen grease. Here’s a breakdown of the most effective cleaners, when to use them, and how to avoid damage to your surfaces.

Mild Dish Soap + Warm Water (Best All-Around Cleaner)

This is our go-to solution for everyday prep. A few drops of quality dish soap in a bucket of warm water can cut through surface dirt and minor smudges without harming the wall’s finish. It’s safe for most painted walls and works especially well on satin or semi-gloss surfaces.

Use a non-abrasive sponge and work from the bottom up in vertical sections, this helps prevent dirty water from running down onto already-clean areas. Just remember: always rinse with clean water after washing. Leftover soap residue can interfere with paint adhesion, leading to peeling and uneven coverage.

Not all dish soaps are created equal. Some homeowners have noticed that lower-end brands leave behind a greasy film or don’t rinse clean. We recommend using a proven performer like Dawn® for consistent results.

Sugar Soap (Heavy-Duty Wall Cleaner)

When dish soap won’t cut it, especially in kitchens or homes with heavy grime, sugar soap steps in. This powerful wall cleaner is excellent for removing tough grease, fingerprints, crayon marks, and smoke stains. It’s commonly used by pros for pre-paint cleaning on older or heavily used walls.

Sugar soap must be rinsed off completely. Some DIYers skip this step and end up with a sticky residue that ruins their paint job. If the wall still feels tacky after it dries, it wasn’t rinsed well enough.

Tip: Wear gloves and ventilate the room when using sugar soap. It’s strong, and while effective, it’s not something you want sitting on your walls for long.

TSP (Trisodium Phosphate)

TSP is the heavy hitter of wall cleaning. It’s an industrial-grade cleaner that cuts through everything, grease, smoke, mildew, and even glossy finishes. But with that strength comes responsibility.

You must wear gloves, goggles, and ensure excellent ventilation when using it. More importantly, you absolutely must rinse the surface afterward. TSP leaves behind a film that can ruin paint adhesion if ignored. 

This is not the cleaner to grab if you're in a rush or unfamiliar with its use. But in the right hands, it can save a project.

Degreasers for Kitchen & Bathroom Walls

Some areas of the home, like the kitchen, bathrooms, or laundry room, demand extra attention. These spaces tend to collect invisible films of cooking oil, steam residue, or product buildup that standard soap can’t remove. That’s where degreasers come in.

We recommend degreasers before painting any wall that’s near a stove, sink, or shower. They break down what you can’t always see, residues that silently sabotage your paint job. Just like with sugar soap and TSP, follow up with a rinse to ensure the surface is paint-ready.

Tip: Even new homeowners often underestimate how much cleaning these “clean” areas need. You might not see the grease, but your paint will know it’s there.

Unconventional but Popular: Swiffers, Mops & Magic Erasers

Not everyone wants to scrub walls by hand, especially in large rooms or homes with vaulted ceilings. Over the years, we’ve seen people get creative, using Swiffer mops with microfiber pads, sponge mops, or even Magic Erasers for spot cleaning.

These options can work if used correctly. Swiffers, in particular, help reach high walls without a ladder. Just make sure the cloth isn’t dripping wet, too much moisture can warp drywall or leave water streaks, especially on matte finishes.

Magic Erasers are perfect for scuffs, but be careful: they’re slightly abrasive. They’ll pull pigment from delicate finishes like flat or chalk paint. Use gently and test in an inconspicuous area first.

How to Properly Clean Your Walls: A Step-by-Step Walkthrough

Even the best products won’t do the job right if the process is wrong. Here’s how we clean walls, because proper prep is what separates a professional finish from a patchy one.

Step 1: Dust First

Before you reach for water or cleaner, remove dust, cobwebs, and loose debris. Use a microfiber duster, dry cloth, or vacuum with a brush attachment, especially along ceiling lines, baseboards, and corners. Skipping this step only pushes dust into the paint later, where it clumps and shows through.

We often start with baseboards and crown molding to catch the dust that collects where walls meet trim. This simple habit makes a visible difference in the final finish.

Step 2: Spot Clean Next

Next, tackle any visible stains, crayon marks, oil spots, shoe scuffs, with a Magic Eraser or degreaser. Spot cleaning before washing the whole wall ensures you don’t spread tough stains around.

When you're dealing with things like marker or grease, clean and then spot prime. Paint alone won’t hide bleed-through, no matter how many coats you apply. A quick primer layer over the cleaned spot locks in stains and prevents frustration later.

Step 3: Wash the Walls

Now you’re ready to clean. Use your chosen solution, whether it’s dish soap and warm water, sugar soap, or a degreaser. Work from the bottom up in vertical sections. This avoids dirty water running down onto already-clean areas and leaving streaks.

Step 4: Rinse & Dry Thoroughly

Once the wall is clean, it’s time to rinse. Use clean water and a new cloth or sponge to remove any residual cleaner. This is not an optional step, any leftover soap, TSP, or sugar soap can cause adhesion issues later.

After rinsing, blot the corners and any crevices with a microfiber towel. These areas tend to hold water and dry slower, which can lead to mildew or streaking. Then let the wall air dry completely, this can take several hours, or overnight if humidity is high.

Rushing through drying is one of the top mistakes we see in DIY jobs. Patience here means fewer problems down the line.

Do You Need to Sand Before Painting?

Not always, but sometimes it’s non-negotiable. This question comes up in nearly every walkthrough we do with a homeowner.

If your walls are already smooth and have a matte or eggshell finish, and you’re not making any patches, then cleaning is likely enough.

But if you're painting over a glossy finish (like semi-gloss or enamel), a quick sanding is a must. Glossy surfaces repel paint. A light scuff with fine-grit sandpaper creates texture for the new paint to grip. Likewise, if you've patched holes or caulked cracks, sand those areas smooth once dry.

Cleaning removes grime. Sanding improves surface texture. They serve different roles, and together, they lay the foundation for a lasting paint job.

We combine both when necessary. We don’t guess, we assess the wall and do what’s required for professional results. If you need help, just reach out to us.

Cleaning New Walls, Patched Walls & Previously Painted Walls

No two surfaces are the same. Whether your wall is fresh drywall, has patched areas, or is painted but scuffed, we adjust our approach. Here’s how we handle the three most common situations.

New Drywall or Skim Coats

Brand new drywall or skim-coated surfaces need a gentle but thorough clean. Even when they look clean, they’re covered in drywall dust, and that dust will cause paint to fail.

We often use a slightly damp microfiber mop to wipe down new drywall surfaces. Avoid any strong chemical cleaners here. The surface is porous and delicate until it’s sealed with primer.

Skipping this step can result in a paint job that peels, flakes, or absorbs unevenly. We’ve seen projects fail simply because no one bothered to clean the dust.

Patched Areas

Any spot that’s been filled or patched should be sanded smooth and wiped clean. Joint compound and filler are chalky, if you leave that dust, it mixes into your paint and causes texture problems.

After sanding, we use a clean, damp cloth to wipe the area. Once dry, we apply spot primer before painting. Without that, patches often show through as dull spots, even after two coats of paint.

Previously Painted Walls

Yes, previously painted walls still need to be cleaned. In fact, they might need even more attention in high-use areas like hallways, bathrooms, or kitchens where invisible residue builds up over time.

Here’s a general rule: the shinier the finish, the easier it is to clean. Glossy and semi-gloss walls are easy to wipe down. Matte or flat finishes are more fragile, clean these with a light touch to avoid damaging the surface.

Common Mistakes to Avoid When Prepping Walls

We’ve been called in to fix a lot of DIY disasters. Often, the problems trace back to something simple that was skipped during prep. Here are a few missteps to watch for:

• Skipping the rinse step after using any cleaner (especially TSP or sugar soap).

• Using too much water, which can damage drywall or leave drying streaks.

• Not cleaning dust after sanding patches, paint can’t stick to loose powder.

• Painting over markers, grease, or crayon without spot-priming.

These may sound small, but they’re the details that determine whether a paint job looks good for one year or ten. We’ve built our reputation on not cutting these corners.

Why ProSmart Painting Never Paints Over a Dirty Wall

It’s easy to spot a rushed paint job. You’ll see streaks, flaking, uneven color, or patches where the paint didn’t bond. And most of the time, it’s because someone skipped the prep, or worse, painted right over dirt, grease, or cracked paint.

That’s not how we do business.

We never paint over a dirty wall. Period. From the moment we arrive for your walkthrough, our team points out areas needing extra prep attention, whether it’s sanding down glossy surfaces, removing cracked paint, or degreasing a kitchen wall that “looks clean” but isn’t.

Another thing that sets us apart? We don’t ask for a deposit. We buy the paint, we prep the space, we do the work, and you only pay when it’s done and you’re satisfied. That’s how confident we are in our process and our people.

And unlike many contractors, we don’t just mask and paint. We inspect. You won’t find streaks or peeling a year later, and you won’t find us cutting corners to save a buck. We’ve heard too many stories from homeowners who paid upfront and got half a job. That’s not the ProSmart way.

Whether we’re painting a new build, helping someone meet HOA requirements, or updating the kitchen of a young family’s first home, we treat every wall like it’s in our own house. Contact us today and give your house the love it deserves.

Frequently Asked Questions (FAQ)

Do I need to clean walls that were just primed?

Yes. Even freshly primed walls can collect dust, sanding residue, or fingerprints during installation. A light wipe-down with a damp microfiber cloth ensures a clean, paint-ready surface

Can I use a steam cleaner to clean walls before painting?

Steam cleaners introduce too much moisture and heat, which can damage drywall or loosen existing paint. Stick with damp cloth methods and cleaners that allow

Is it okay to paint over a washable marker or crayon after cleaning?

No. Even if the surface looks clean, markers and crayon wax can bleed through paint. These stains should be cleaned thoroughly and then spot-primed with a stain-blocking primer before applying your topcoat.

What should I do if the walls feel sticky after cleaning?

A sticky or tacky wall often means soap or cleaner residue is still present. Wipe the wall again with clean, warm water and a fresh cloth. Let it dry completely before painting. This is especially common when using sugar soap or low-quality dish soap.

Can I clean and paint the same day?

Only if the wall is completely dry. Depending on humidity and ventilation, walls can take several hours, or even overnight, to dry fully. Painting too soon can lead to blistering, bubbling, and poor adhesion. When in doubt, wait.