How To Clean Walls Before Painting

If you’ve ever rolled a gorgeous new color and watched it turn blotchy in weird spots, you’re not alone, I’ve been there. The truth is, the secret to a pro-looking result isn’t a fancy brush: it’s clean walls. In this guide, I’ll walk you through how to clean walls before painting without overcomplicating it. We’ll tackle what’s on your walls (grease, dust, mystery smudges), the safest cleaners to use, and a step-by-step routine that actually works. A little prep now saves you from peeling, flashing, and “why did I do this?” later.

Key Takeaways

Cleaning walls before painting is non-negotiable for strong adhesion, an even sheen, true color, and a longer-lasting finish.
Follow this order for how to clean walls before painting: clear and protect, dry-dust top to bottom, spot-treat grease/marks/mildew, gently wash with mild soap (or a TSP substitute), rinse as you go, and let walls dry completely.
Match the cleaner to the mess—use a degreaser for grease, bleach or 3% hydrogen peroxide for mildew, isopropyl alcohol or a melamine sponge for marks, and citrus remover for adhesive—and always rinse and ventilate.
Stay safe by cutting power around outlets, ventilating strong cleaners, and treating pre-1978 paint cautiously to avoid lead exposure.
To master how to clean walls before painting, finish with the swipe and tape tests, then prime stained, smoky, mildewed, glossy, or repaired areas to lock in a professional result.

Why Cleaning Walls Matters For A Flawless Paint Job

I learned the hard way years ago: I rushed, painted over a slightly grimy kitchen wall, and within a week the paint fisheyed around the stove like raindrops on a windshield. Paint doesn’t bond well to contaminants. Dust, oil, soap scum, and nicotine form a barrier that makes fresh paint struggle to adhere.

Clean walls give you:

Better adhesion (paint stays put instead of peeling or scratching off)
More even sheen (less flashing or dull patches)
Truer color (stains don’t ghost through as easily)
Longer-lasting finish (so you’re not repainting in a month)

If you remember nothing else, remember this: a wall that looks “fine” is often still dirty. A quick clean can be the difference between “Did you hire a painter?” and “Oh… you did it yourself.”

What You’re Working With: Surfaces, Contaminants, And The Right Cleaners

Not all walls are the same, and not all grime is created equal. Knowing what you’re up against helps you choose the right cleaner and avoid damaging the surface.

Common surfaces

Painted drywall (most homes): latex paint in flat, eggshell, satin, or semi-gloss. Flat is delicate, go gentle. Semi-gloss is tougher.
Plaster: often older homes: can handle light washing but don’t soak.
Wood paneling/trim: clean gently, avoid harsh alkalines that dull finishes.
Brick/tile: needs degreasing and good rinsing: textured surfaces trap dust.

Usual suspects (aka the gunk)

Dust and cobwebs (especially on ceilings and near vents)
Cooking grease and aerosols (kitchens and dining areas)
Hand oils around switches, hallways, and stairwells
Soap scum and hairspray (bathrooms)
Nicotine/smoke residue
Kids’ art: crayons, markers, stickers, and adhesive residue
Mildew in damp rooms

Smart cleaner choices

Everyday dirt: a few drops of mild dish soap in a gallon of warm water. Rinse with clean water.
Grease: a degreaser (diluted per label) or TSP substitute. True TSP works well but can leave residue, rinse thoroughly.
Mildew: kill it or it’ll bleed through. Use a bleach solution (about 1 cup household bleach per gallon of water) or 3% hydrogen peroxide directly. Ventilate and never mix bleach with ammonia or vinegar.
Nicotine/smoke: TSP or a heavy-duty wall cleaner, then prime with a stain/odor blocker.
Marker/crayon: isopropyl alcohol on a cloth for marker: a melamine sponge for crayon (go gently, these can burnish flat paint). Rinse after.
Adhesive/goo: a citrus-based adhesive remover works, then wash and rinse.

Rule of thumb: start mild, escalate only if needed, and always rinse so primer and paint can grip.

Tools, Supplies, And Safety Essentials

I keep a simple kit for wall prep so I’m not scrambling mid-job.

Microfiber cloths and non-scratch sponges
Soft brush or microfiber mop on an extension pole
Vacuum with a soft brush attachment
Two buckets (wash and rinse) + warm water
Mild dish soap, degreaser/TSP substitute, bleach or hydrogen peroxide (for mildew)
Spray bottles for spot treatments
Painter’s tape, drop cloths/plastic, and a step ladder
Nitrile gloves, eye protection, and a respirator if using strong cleaners

Safety notes I don’t skip:

If your home was built before 1978, treat painted surfaces with caution for lead. Avoid dry sanding: use gentle washing and consult a pro if you suspect lead.
Turn off power at the breaker before removing switch plates or cleaning around outlets. Keep water away from live electrical.
Ventilate when using bleach or strong cleaners.

Step-By-Step: Clean Walls The Right Way

Here’s the rhythm that’s saved me time (and repaints). It’s how to clean walls before painting without overthinking it.

Clear and protect

Move furniture, cover what remains, and lay drop cloths. Remove wall art, nails, and switch/plate covers. Tape over outlets/switches after plates are off.

Dry dust from top down

Use a vacuum brush or a microfiber mop on a pole to grab ceiling cobwebs, crown molding dust, and walls. Don’t skip baseboards, paint loves to fail where dust hides.

Pre-treat obvious spots

Degrease kitchen hotspots (near the stove and backsplash). Hit marker/crayon with isopropyl alcohol on a cloth. Treat mildew with bleach solution or hydrogen peroxide: let it dwell 10 minutes, then rinse. Remove adhesive with a citrus remover and wash afterward.

Mix a gentle wash

In a bucket: warm water + a few drops (1–2 tsp) of mild dish soap. In a second bucket: clean rinse water. If the walls are very dirty, use a TSP substitute per label.

Wash in sections

Lightly dampen a microfiber cloth or sponge, wring it nearly dry. I like working from the bottom up to avoid dirty drips staining clean, dry areas: then I do a quick pass top-down to catch runs. Use light pressure on flat finishes to avoid burnishing.

Rinse as you go

Follow each washed section with a clean-water wipe. Swap out rinse water often (cloudy water = it’s time).

Manage drips and edges

Keep an eye on corners, trim lines, and above baseboards. A dry towel in the other hand is your friend, catch drips before they set.

Final wipe and airflow

A dry microfiber wipe speeds drying and knocks down any lingering residue. Open windows, run a fan, and let the walls dry completely before the next steps.

Optional but worth it after cleaning: lightly scuff glossy areas with 220-grit, vacuum the dust, and wipe with a damp cloth. Clean first, then scuff, never grind dirt into the surface.

Troubleshooting Tough Spots And Special Rooms

Some rooms just fight back. Here’s how I handle the usual troublemakers.

Kitchens: Grease travels farther than you think, ceilings above the stove, cabinet sides, and the wall behind the trash bin need extra attention. Use a degreaser, then rinse twice. If it still feels slick, it’s not clean yet.
Bathrooms: Kill mildew (bleach mix or hydrogen peroxide), rinse, and dry thoroughly. If you can, run a dehumidifier for an hour. For persistent mildew areas, plan on a mold-resistant, stain-blocking primer.
Kids’ rooms and hallways: Crayon and scuff marks often respond to a melamine sponge, but go light, especially on flat paint. For permanent marker or heavy stains, spot-prime with a shellac or oil-based stain blocker after cleaning.
Smoke/nicotine: Wash with TSP or a strong cleaner until your cloth stops turning yellow. Then use a dedicated odor- and stain-blocking primer before paint. Skipping this is how you end up with bleed-through.
Textured walls, brick, or masonry: Vacuum first to pull dust from crevices. Use a soft brush with your cleaner and rinse carefully. Don’t flood porous surfaces, let them dry fully.
Old wallpaper residue: Remove glue with warm water + a bit of dish soap or an enzyme remover. Rinse until the wall no longer feels slippery. Seal with a problem-surface primer (I like a drywall sealer/”gardz” type) before painting.
Potential lead paint (pre-1978): Avoid sanding. Gentle wet cleaning only, and talk to a pro about safe prep and encapsulating primers.

Drying, Readiness Checks, And Priming Before Paint

After washing, I give walls time, rushing here invites problems.

Drying time: Typically 30–120 minutes depending on humidity and ventilation. Fans and open windows help. If it feels cool or clammy, it’s not dry.
The swipe test: Run a clean hand over the wall. If it feels chalky or leaves residue, wash again or plan on a sealing primer. If it feels squeaky-clean and matte (not slick), you’re good.
Adhesion check: Press a piece of painter’s tape on the wall and peel. If paint lifts easily, you’ll want a bonding primer after a light scuff.

When to prime:

Stains, smoke, or mildew were present
Big color changes (dark to light, or vice versa)
Glossy or previously oil-based surfaces
Patched areas or repaired drywall

Primer picks I reach for:

Acrylic multi-surface primer for general walls
Bonding primer for glossy or slick areas
Stain-blocking primer (shellac or oil-based) for smoke, marker, water stains, and knots
Mold-resistant primer for bathrooms or damp zones

Caulk gaps after cleaning and before priming, then allow it to cure. A clean, dry, primed wall takes paint beautifully, this is where the finish starts to look expensive.

Conclusion

Clean walls don’t just help, they decide whether your paint job looks pro or patchy. My routine is simple: dust thoroughly, spot-treat stains, wash gently, rinse well, dry completely, then prime where needed. That’s how to clean walls before painting without the headaches.

Quick hits I keep in mind:

Start mild, rinse often, and ventilate
Treat mildew and nicotine like stains, they need cleaners and primer
If it still feels greasy, it is: keep cleaning
Respect old paint (possible lead) and go gentle

Take your time here and your color will reward you. The best part? You only have to do the heavy prep once, then you get to enjoy the transformation every time you walk in the room.

Frequently Asked Questions

Why should I clean walls before painting, and what happens if I skip it?

Cleaning walls improves adhesion, evens sheen, and helps stop stains from ghosting through. Skipping it can cause fisheyes over grease, patchy flashing, poor color, and premature peeling—especially in kitchens and baths. Even “clean-looking” walls carry dust and oils that block paint. A quick wash makes the finish last longer and look professional.

What’s the step-by-step method for how to clean walls before painting?

Protect and clear the room. Dry-dust top-down. Pre-treat: degrease kitchens, kill mildew (10‑minute dwell), alcohol for marker, citrus for adhesive. Mix warm water with a few drops of dish soap. Wash in sections bottom‑up, then quick top‑down pass; rinse as you go, catch drips. Dry thoroughly. Optionally, lightly scuff glossy areas with 220‑grit after cleaning.

Which cleaners should I use to clean walls before painting—grease, mildew, and marker?

To clean walls before painting, wash general grime with warm water plus a few drops of dish soap, then rinse. For grease, use a degreaser or TSP substitute. For mildew, apply a bleach mix (1 cup per gallon) or 3% hydrogen peroxide, then rinse. For marker/crayon, use isopropyl alcohol or a melamine sponge. Never mix bleach with ammonia or vinegar.

How long should walls dry after cleaning before priming or painting?

Most walls dry in 30–120 minutes with ventilation. Use the swipe test: if it feels slick, cool, or leaves residue, keep drying or rewash. Do a quick adhesion check with painter’s tape; if paint lifts, plan a bonding primer. Fans and open windows speed drying—paint only when the surface feels clean and fully dry.

Can I use vinegar to clean walls before painting?

White vinegar can cut light soap scum and minor odors, but it’s acidic and weak on kitchen grease or nicotine. If you use it, dilute, test inconspicuously, and rinse thoroughly so primer and paint can bond. Never mix vinegar with bleach. For greasy walls, a degreaser or TSP substitute is more effective.

Is steam cleaning a good way to prep walls before painting?

Usually no. Steam can drive moisture into drywall or plaster, soften joint compound or wallpaper glue, and extend drying time—risking adhesion problems. If you must, keep passes brief, use low steam, and ventilate aggressively. A safer approach is warm water, mild soap, microfiber wiping, thorough rinsing, and complete drying before priming.