How to Remove Mold from Wood and Prevent it from Reappearing

It’s not uncommon to find the wood in our homes infected by mold. Basements, kitchens, and bathrooms are common areas where mold can lurk. However, it can also grow on the back of furniture and windowsills. This article will discuss what mold is, how dangerous it could be to your health, and what you can do to remove it. Once removed, we’ll also discuss steps you can take to prevent it from returning.

What is Mold?

Mold is a member of the very common fungi family, which includes yeast and mushrooms. It forms an important part of our environment and is found wherever you find moisture and oxygen. 

Fungus Settled on Wood. Photo: 123rf.com

In nature, mold is important in breaking down dead organic matter such as plants and trees. Unfortunately, mold doesn’t differentiate between a dead tree in the forest and a plank of wood in our home. If it gets damp, mold will grow on it.

Mold reproduces using spores which are microscopic cells that float in the air. Our environment is normally full of mold spores, and in most cases, their presence is not an issue for healthy adults. 

However, mold can flourish in the presence of damp, still air, and it grows rapidly. If inhaled, many mold spores cause an allergic reaction in healthy adults and asthma attacks in asthmatics. However, some types of mold are more severe and can cause disease, while others are toxic to humans.

Health Effects of Mold

Before we discuss health effects, it’s worth starting with a clarification. When we talk about mold’s effect on human health, we speak of normally healthy human adults. However, all mold should be considered potentially dangerous for children, the elderly, or those with health conditions.

We can classify the impact of mold on healthy adult humans into three categories:

Allergenic – these molds can cause a runny or blocked nose, irritation of the eyes and skin, and wheezing. In severe cases, they can induce swelling, breathing difficulty, cramps, dizziness, and abdominal pain. When inhaled by asthmatics, they can trigger an asthma attack.

Pathogenic – these molds can cause disease in humans. In mild cases, the disease is superficial, causing skin infections, athlete’s foot, and nail infections. If the mold gets past our skin, we can develop an infection. In severe cases, the mold can threaten our lives by attacking our bodily organs in what is called a systemic reaction.

Toxigenic – these molds are dangerous. They can produce what are known as mycotoxins, and the symptoms can range from fever, fatigue, and a weakened immune system to disorders of the central nervous and hormone systems, liver damage, and cancer.

Here’s a helpful video by Paul Cochrane discussing the effect of mold on our bodies:

YouTube player

Twelve Molds Found in Homes

The following twelve molds may be found in your home, all allergenic, while a few are more concerning – click on the link to download the file:

Common Molds – PDF

Safety Precautions When Removing Mold

Generally, it is best to get a professional firm to manage removal and cleaning if you have a widespread mold problem. The EPA suggests that if the moldy area is greater than ten square feet, seek professional help. However, you can easily manage mold removal for smaller areas by following some basic safety precautions.

The aim is to protect your skin, eyes, and lungs from contact with the mold because once you begin the removal process, you’ve disturbed the spores, and they’ll be floating around everywhere. I strongly advise you to use the following safety equipment to protect your health when removing mold:

  • An air mask – must be rated at least N95, but consider an N100 for the nastier molds or if you are susceptible to allergies. Be sure you fit it to your face correctly.
  • Use disposable paper overalls to prevent getting mold on your skin and clothes. 
  • Goggles with a good seal to your face will protect your eyes and face area.
  • Rubber gloves will round out the safety precautions by keeping your hands and wrists mold-free while sealing over the overall cuffs.

Methods of Mold Removal

There are as many home remedies for mold removal as there are species of mold. However, a few methods are proven to be effective, and we’ll run through them from least to most effective.

Before we begin applying chemicals, let’s talk about mold spores. You’ll read on every blog that you should use a vacuum to suck up the mold spores and any loose mold before you start removal techniques. However, I have a slight problem with this. 

Vacuuming is fine if you have a vacuum with a good Hepa filter and it’s functioning well. If you don’t have a Hepa filter or the vacuum is a bit leaky, then congratulations, you’ve just contributed to spreading the mold to a wider area than it would otherwise have been. I work on the principle that the less you disturb the mold spores, the better. I prefer not to vacuum but go straight in with a bit of chemical warfare.

You’ll also read that water and dishwashing detergent will kill mold. It doesn’t. Yes, it’ll remove the visible mold and clean non-porous surfaces, but it is not toxic to mold. If I have mold growing due to moisture and heat, I’m not convinced adding more moisture will help, even if it includes soap.

Liquid mold removers

Four readily available substances will kill mold, listed from least to most effective:

  • Vinegar
  • Tea tree oil
  • Bleach
  • Borax

Vinegar

Vinegar has antibacterial and antifungal properties. The ordinary white vinegar you use at home contains about 5 to 8 percent acetic acid, which kills some microorganisms and fungi. Note the word some; it doesn’t get every type of mold. For example, it will kill penicillium, but not aspergillus.

  1. Apply all your protective gear described above.
  2. I like to use a spray bottle to apply the vinegar to the surface and then leave it to work for an hour or so. 
  3. Use a soft bristle brush to scrub away the mold. I use more vinegar to keep the area moist and dampen errant mold spores. 
  4. Once all the mold is loose, use a cloth to clean and dry the surface.
  5. Be sure to dispose of the cloth and the brush once done.

There are some precautions to observe when using vinegar:

  • Being acidic, it will etch and dull surfaces like limestone or marble. It also has a corrosive effect on metals.
  • Do not use it on concrete. The vinegar eats away the cement binding the aggregate and may damage and weaken the surface.
  • Be careful on wood with a protective coating applied, as the vinegar can strip the coating.
  • If you are using vinegar on furniture containing leather, dilute the vinegar with water at a 50/50 ratio and use it sparingly. Do not let the mixture sit on the leather for extended periods.

Tea tree oil 

Tea tree oil is a distillation from the tree Melaleuca alternifolia and is long known to have good antimicrobial action. Studies in 2015 have shown that tea tree oil also has excellent anti-fungal characteristics with a greater effect than vinegar and some commercial mold removal products. 

Mix a teaspoon of tea tree oil with one cup of water. Then follow the same steps shown with the vinegar. 

Precautions to observe when using tea tree oil:

  • While safe overall, it may be toxic if swallowed. Please keep it away from children.
  • Be careful around pets, as dogs and cats can be adversely affected through skin contact or ingestion.

Bleach

Ordinary household bleach consists of around 3% hydrogen peroxide and is active against six molds commonly found indoors. Follow the same steps as you would applying vinegar, but only leave the bleach for ten minutes before scrubbing it off. Bleach can weaken the cellular structure of the wood when left for too long. 

Observe the same precautions as you would when applying vinegar. Both are quite capable of etching metals and damaging surfaces. Also, never mix bleach with any other chemical. It can produce toxic gasses.

Borax

Of our four chemicals, borax is the best to kill mold and inhibit its return. It is a naturally-occurring alkaline chemical that is kinder to the environment than bleach and less toxic to humans. It should, however, still be handled with care.

  1. Apply your protective gear.
  2. Mix 1 cup of borax with one gallon of warm water.
  3. Fill a spray bottle and spray the mold to be removed. Allow it to sit for five minutes
  4. Scrub the mold to remove it, and wipe clean with a cloth.
  5. There is no need to rinse the surface, as the borax will maintain a mold inhibiting action after removal.

Basic precautions to observe:

  • Never mix borax and bleach.
  • While of low toxicity, borax should not be ingested and must be kept away from children and animals.

Mechanical mold removal

If you’ve tried all the previous chemical solutions to no avail, then the last act would be to sand the wood. Sanding allows you to remove all the surface mold and much of the mold hidden in the wood’s pores.

Use your protective gear, as the sawdust and mold will become airborne, increasing the risk of inhaling mold spores. Once the wood is sanded back to a point you’ve removed visible mold traces, you can use a borax solution to kill any remaining spores.

Once the wood is dry, be sure to protect the wood with a surface coating of your choice to prevent reinfestation.

Stopping Mold from Reappearing

At the start of this article, I mentioned that mold spores are everywhere, and there’s nothing we can do to prevent their access to our homes. However, they need an environment to support the spores growing into the visible mold. If we can deny them that environment, we can stay mold-free.

  • Mold thrives in damp, warm, still environments. That’s why bathrooms and basements are prone to mold growth. Install fans or ensure adequate airflow to dry any steam, condensation, or humidity. If the moisture doesn’t have time to sit, mold is less likely to form. 
  • Consider protecting the surface with either a mold-inhibiting paint or a polyurethane coating. While mold will form on any surface, it is easier to remove from a smooth surface finish than from a porous surface like bare wood. You can purchase waterproof coatings for basements and masonry or mold-resistant paints.
  • If you have furniture with a natural finish, beeswax polishes are a great natural product. They have anti-fungal and anti-microbial properties and form a layer between the wood and moisture. 
  • Dust, vacuum, and wipe all organic surfaces regularly. Regular cleaning will reduce the volume of mold spores over time and reduce the chances of mold gaining a foothold.
  • If the mold gets into fabrics and carpets, it can be extremely difficult, if not impossible, to remove. You can launder moldy clothes in a borax solution, but carpet tiles, carpet, and drywall may need to be replaced.

This video is a great overview by Matt Risinger of how you can prevent mold growth in your home:

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Conclusion

Preventing mold is a whole lot easier than removing it. The one precaution we can all take to prevent mold on wooden surfaces is to ensure adequate ventilation. When that’s impossible, such as in basements or bathrooms, try to remove all moisture sources and be sure to protect the surface of the wood. Finally, good old-fashioned elbow grease goes a long way toward keeping mold under control through regular dusting, vacuuming, and wiping down surfaces.

Frequently Asked Questions

Yes. But you must ensure adequate ventilation around the wood, reduce moisture ingress, and preferably protect the surface of the wood. Regular dusting, vacuuming, and wiping down also help.

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Yes. Your success depends on how long the mold has been there and how far it has progressed. Over time it will rot the wood, requiring more drastic removal techniques. You can remove light mold easily with vinegar, bleach, or borax.

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Some can be, yes. Most molds cause allergies that are uncomfortable but not life-threatening. However, all can be dangerous for people with asthma, compromised immune systems, the young or the aged. A few are toxic to humans or can cause infections.

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William Stewart

The proud owner and lead writer of WoodImprove.com. Started writing in 2018 and sharing his love and passion for wood treatments and crafts.

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