How to Clean Window Sills of Mold, Dirt, and Scuffs

Window sills can take a beating with daily use. If you’re dealing with dust, grime, and potentially mold, you’re not alone. We’ll show you how to get your window sills and tracks pane-fully clean (pun intended).

How to clean window sills like an expert

The thing about window sills is that they are “welcoming” to dust and dirt over time. The outdoor sills collect pollen, dirt, and debris blown in by wind or rain, while indoor sills attract pet hair, crumbs, and other household debris. In addition, humidity and rainwater can lead to mold growth on the windowsill.

Whatever the source of the dirt, it's crucial to keep your windowsills clean to maintain a healthy living space and to keep your house looking neat. 

In this article, we share safe, effective methods for cleaning dirt, dust, scuffs, and mold from your windowsills and ledges.

What is the black stuff on my windowsill?

If the black stuff on your windowsill is fuzzy and the surrounding area is damp, it’s most likely mold. 

Black mold grows on a window sill when there is a moisture build-up. For example, you will notice wetness around your windows during winter due to water condensation. This water drips to the bottom of the windows, where it accumulates over time, damages the drywall below, and encourages mold formation.

Other causes of the black stuff (mold) on your windowsill could be a broken heating or ventilation system, leaking pipes, a leaky roof or window frame that allows rainfall to pool on your windows, steam from cooking or taking a bath, and insufficient airflow.

Unfortunately, black mold can be hazardous to your health as it causes severe allergic responses and illnesses that affect the respiratory tract and the neurological system. 

Here’s how to clean your window sills like an expert.

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What you’ll need to clean your window sill

• Rubber gloves
• Safety goggles 
• Spray bottle 
• Sponge 
• Microfiber clothes 
• Protective mask 
• Soft scrub brush 
• Water
• Dishwash
• Baking soda
• A vacuum cleaner with a HEPA filter
• Distilled white vinegar 

How to clean mold from a window sill (3 ways)

Method 1: White vinegar

Vinegar is a natural acid that effectively kills mold and removes its stains from most window sills. In addition, the acidic properties of vinegar break down mold spores and inhibit their growth. Besides cleaning mold from window sills, you can use white vinegar to clean window tracks and clear blocked drains, among other home-cleaning functions.

Wear protective clothing

Mold can be harmful to your health if inhaled or ingested, so it is important to take safety precautions before starting the cleaning process. For example, wear gloves to protect your hands, eye protection to prevent mold spores from getting into your eyes, and a face mask to avoid inhaling any airborne mold spores.

Prepare your vinegar solution and spray

Mix equal parts of white vinegar and water in a spray bottle. Spray the solution directly onto the moldy areas of the window sill. Be sure to cover the entire affected area with the solution. Next, allow the vinegar solution to sit for at least 1 hour. This will give it time to penetrate the mold and kill any remaining spores.

Scrub the affected area

After the solution has been allowed to sit for at least 1 hour, use a scrub brush or sponge to scrub the moldy areas. Be sure to scrub thoroughly to remove all the mold.

Rinse and dry thoroughly

Once you have removed all the mold, rinse the window sill with clean water to remove any remaining vinegar solution. Then wipe the window sill thoroughly dry with a clean cloth to prevent any moisture from remaining on the surface.

Method 2: Hydrogen peroxide

In high school chemistry, we learn that hydrogen peroxide is a powerful oxidizer. 

Here’s how it works: when applied to the mold on your window sill, it releases oxygen, which attacks and kills the mold spores.

Another big advantage of using hydrogen peroxide is that it’s non-toxic, environmentally friendly, and safe to use around children and pets. Still, be sure to wear gloves and eye protection while you work.

• Mix equal parts of hydrogen peroxide (3%) and water in a spray bottle. Shake the bottle to mix the solution well.
• Spray the solution generously on the moldy areas of the window sill. Make sure the solution covers all the moldy spots.
• Allow the solution to sit on the moldy areas for 10-15 minutes. This gives the hydrogen peroxide time to penetrate and kill the mold.
• Use a scrub brush to scrub the moldy areas of the window sill.
• Next, rinse the window sill and wipe it with a dry cloth. This will remove any remaining residue from the mold and cleaning solution.

Method 3: Baking soda

Baking soda has other functions besides baking bread and muffins. It is also a natural and gentle abrasive that helps to remove mold without damaging the surface.

• First, clear the area around the window sill to prevent any household items from being contaminated during cleaning.
• Using a vacuum cleaner with a HEPA filter, vacuum the window sill and surrounding area to remove any loose mold spores or debris. Dispose of the vacuum bag or empty the canister outside, away from open windows or doors.
• Mix equal parts baking soda and water in a small bowl to create a paste. Then apply the baking soda paste to the moldy area of the window sill using a scrub brush. Cover all the affected areas and work the paste into any crevices or cracks.
• Let the baking soda paste sit on the window sill for 10 to 15 minutes. This will allow the paste to penetrate and loosen the mold.
• Using the scrub brush, gently scrub the moldy area of the window sill in a circular motion, applying moderate pressure to remove the mold.
• Wipe away the baking soda paste and any remaining mold using a clean, damp cloth. 
• Finally, rinse the window sill thoroughly with clean water and dry it completely using a dry cloth or towel.

How to clean dirt and dust from a window sill

If your window sill merely has dirt and dust, here’s how to get it shining new once again.

Using dishwashing soap 

• Use a soft-bristled brush to gently remove any loose dirt, debris, or cobwebs from the window sill. Make sure to get into all the nooks and crannies.
• Use a vacuum cleaner with a soft brush attachment to remove any remaining dirt or dust from the sill. Vacuum in all directions, paying special attention to the corners and edges.
• Mix a few squirts of dishwashing soap with warm water in a bucket. Stir together till it’s fully dissolved. Then dampen a microfiber cloth with the cleaning solution and wring it out well. 
• Use the dampened microfiber cloth to wipe down the entire surface of the window sill, including the edges and corners. 
• Repeat the process till your window sill is completely clean.
• Once you're satisfied with the cleanliness of the window sill, dip a fresh microfiber cloth in warm water and use it to wipe down any residue and the cleaning solution. 
• Finally, use a dry microfiber cloth to wipe away any excess moisture.

How to clean scuff marks from a window sill

Non-gel toothpaste without whitening agents can help to remove scuff marks from a window sill without damaging the surface. Here’s how to use it.

• Dampen a clean cloth with water and wring out the excess water.
• Apply a small amount of toothpaste to the damp cloth.
• Gently rub the scuff marks on the window sill with the cloth using a circular motion.
• Continue rubbing until the scuff marks have been removed.
• Once you have removed the scuff marks, wipe down the window sill with a clean, damp cloth to remove any leftover toothpaste residue.
• Dry the window sill with a clean towel or paper towel.

What is the best way to clean window tracks?

The best way professional home cleaners recommend for cleaning window tracks is to use baking soda and vinegar. They are non-toxic, affordable, easy to use, and effective. 

The process starts with vacuuming the tracks and adding baking soda, followed by a vinegar spritz. Then, use an old toothbrush to loosen dirt in the tracks and wipe clean with a microfiber cloth.

For more detailed steps and other methods that do not require vinegar, read our article on how to clean window tracks.

Cleaning your window sills only takes 20 minutes

Most people believe cleaning their window sills is a daunting task that takes hours. However, by using the supplies and methods explained in this article, you can easily clean your window sills in under twenty minutes and maintain them for longer.

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