How To Remove Mildew Stains From Wood

Wood absorbs moisture, especially unfinished wood, which makes it a perfect place for mildew to grow.

Mildew can stain wood in various unappealing colors, and mildew and other molds are dangerous for your health.

You should remove the mildew as soon as possible.

While it can seem overwhelming at first, we’ve done some research on how to remove mildew stains from wood.

Removing mildew stains from wood can be quickly done.

All you need are some household cleaning supplies and some elbow grease.

What You’ll Need

You will need a few simple things to remove mildew stains from wood properly.

Both a mask and gloves are necessary when cleaning up mold.

The mask should cover your nose and mouth to prevent mold spores from getting into your lungs.

I recommend this Clear Face Mask that I found on Amazon.

It has a bracket built inside that reduces the friction frequency between mask and face to protect the lining from getting stained, thus allowing you to wear it longer.

Any good rubber cleaning glove will work fine, but I recommend these Cleanbear Synthetic Rubber Gloves if you don’t have any.

They get outstanding reviews on Amazon.

You can also wear safety glasses to maximize your protection.

The HEPA filter is necessary because you are dealing with mold. In large amounts, mold can be toxic, and the HEPA filter helps keep mold particles contained.

If you don’t have a vacuum with a HEPA filter, I recommend the NEQUARE Vacuum Cleaner, 20Kpa Stick Vacuum with Self-Standing, Dual-HEPA Filtration.

It’s one of the most economical options and still gets excellent reviews.

Once you have finished using your vacuum, empty it outside into a plastic bag to prevent the mold particles from settling elsewhere in your house.

  • Dishwashing soap
  • Warm water
  • Spray bottle
  • Cleaning rag
  • Laundry detergent
  • Bleach
  • 100-grit sandpaper

Now that you have the items, read on learn how to remove mildew stains from wood.

Removing mildew stains from wood requires some elbow grease, but if you put in the work, you will be rewarded in four easy steps with clean, mildew-free wood that you can enjoy.

Remember to wear your mask and gloves throughout this process to protect yourself from mold spores.

1. Vacuum The Affected Area

Once you have spotted mildew stains on your wood, you need to act quickly.

Any delay could allow the mildew to grow and become more difficult to remove entirely.

Using a vacuum with a HEPA filter, vacuum the affected area.

This will remove any loose mold spores, as well as any dirt. 

Pro tip: Empty the vacuum outside into a plastic bag.

Going outside prevents any escaping mold spores from settling into a different area of your house.

Seal up the plastic bag completely to ensure the mold spores do not escape.

2. Wash The Affected Area With Soap And Water

Mix a tablespoon of dishwashing soap with a spray bottle of water.

This will adequately dilute the dishwashing soap.

Spray your mixture over the mildew stain and gently clean it with your cleaning rag.

Ensure to dry the area as you go with a towel or a dry cleaning cloth to prevent water from seeping into your wood.

Pro tip: You can also use a mixture of equal parts vinegar and water if you find the dishwashing soap unsatisfactory.

Vinegar works well because it kills many forms of mold, including mildew.

Spray the vinegar and water mixture over the mildew, let it sit for an hour, and then wipe the mildew away with a dry cleaning rag. 

3. Wash Affected Area With The Diluted Bleach Mixture

If the mildew stain is deeper than the surface of your unfinished wood, you will need a stronger cleaning solution—mix 20 parts warm water, ten parts bleach, and 1 part laundry detergent.

Use your cleaning cloth to apply the mixture to the affected areas, and let it sit.

The water and soap will clean out the mildew stain, and the bleach will kill any mildew left on the surface.

Allow your wood to air dry; you can use a towel or a fan to speed up the process. 

4. Sand The Affected Area

If the mildew stain goes deeply below the surface of the wood, you can use your sandpaper to get the rest of it out.

Try Fandeli 36025 100 Grit Multipurpose Sandpaper Sheets.

This is the only way to truly get all the mildew out of your wood to prevent further mildew growth and to preserve the appearance of your wood.

Slowly sand away the affected area, trying not to damage the unaffected areas until there is no longer any trace of the mildew.

Once you have finished sanding, you should vacuum the wood again to remove any sawdust and loose mold spores. 

Video of How to Remove Mildew Stains from Wood

Here is a video demonstrating how to remove mildew stains from wood.

Frequently Asked Questions

What should I do if there is a lot of mildew to clean? 

If the mildew stain covers more than 10 square feet, you should call in a professional cleaner.

Mold exposure in that quantity can be dangerous for your health if you do not handle it properly, so it’s best to let the experts deal with it.

If the mildew stain is less than 10 square feet, you can probably handle it yourself.

Mildew stains can come in a variety of colors, including red, green, and black.

Before you start cleaning, verify the stain is not toxic black mold.

Toxic black mold is hazardous if inhaled, so don’t touch it.

If you are unsure, please consult a professional.

Your health is not worth the risk of mishandling black mold. 

What should I do if I find mildew stains on painted or finished wood?

It’s usually easier to clean mildew stains off painted or stained wood because the finish acts as a barrier between the mildew and the wood itself.

All you need is the dishwashing soap and water mixture to clean the mildew stain off, leaving the wood free from mildew and its unsightly stains.


I hope you have enjoyed learning how to remove mildew stains from wood.

While you need to act quickly once you have found mildew stains, you can remove them easily with some determination and a few household cleaning items.

Remember that mildew thrives in moist environments, so once you have removed the mildew stain from your wood, work to limit the amount of moisture the wood is exposed to in the future to prevent any further mildew stains.