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Why Is My Wood Floor Turning Black

When the color of your oak wood turns floor is black, the exposure to sunlight comes to mind. However, it can mean the presence of both moisture and mold. Moisture promotes the growth of Mold and it usually comes from above. Moisture can penetrate the coating and the surface of the wood floor.

However, it can also come from beneath the floor if it is wet. You can kill mold and also remove the discoloration with the use of wood bleach. However, the need to stain and refinish the wooden floor or part of it may be required.

Difference Between Surface Staining And Wood Discoloration

There is a distinction between the black discoloration that has settled on the surface of your oak floor and the discoloration of the wood. You can trace back the problem to moisture in both cases.  But first of all, removal is relatively easy and does not require finishing or sanding. 

If the wood itself is black, the discoloration can be caused by mold or tannins in the wood that reacts with minerals in the water. In both scenarios, the cure is to remove the coating and bleach the wood. Or better still, replace the affected boards with new ones.

How To Kill Mold On A Wooden Surface

Scientific studies show mold only does well in the presence of moisture. So you must always ensure to keep your wood floor dry. One way to achieve this is by putting on heaters and fans. Additionally, if there is a central heating system in your house, then ensure the heat is increased. Also, make sure you opened the vents in the affected room.

Once you notice the mold growing on the surface of the wood floor but hasn’t gotten into the coating, kill it off quickly. This is done by washing it with a solution of chlorine bleach and water. Better still, to be sure, you can use a non-water based hardwood cleaner. Using a refreshing coating or wax application makes it possible for the shine of the affected areas to be restored. 

The Best Solutions For Blackened Wood

Unfortunately, the blackening of woods is usually noticed when the mold has penetrated the wood surface. This makes remediation much more challenging. It is also essential to know that if floor is dry, sanding is required. So you should use a hand sander to sand the surface of the wooden floor and also apply wood bleach. Equally, you should use a floor sander if the damage is severe and extensive. 

Another way to prevent the appearance of black spots on wood is through the application of chlorine bleach. This will help to kill mold. Furthermore, ensure it is neutralized with a solution of baking soda and water. Afterward, you rinse and dry the wood. 

If there are still black traces of water, then the wood should be treated with a solution (saturated) of oxalic acid crystals and water. Afterward, it can be neutralized and rinsed.

How To Remove The Stain From The Surface Of Wood Floor

Here are steps to remove stains from a wooden surface:

First Step 

First, you should sand the protective coat of the area that is dark. Then use fine sandpaper to reduce the risk of the wood gouged. You shouldn’t sand the dark stain because this will likely leave a depression in the wood.

Second step

The second step is to use a neat cloth to clean the wood. This will remove the sanding dust from the surface of the wood.

Third Step

Ensure to put on your eye goggle to protect your eyes. Once you have worn your eyes protection, simply use the brush to apply a very thin layer of wood bleach to the stain 

Fourth Step 

Then exercise some patience and wait for a couple of hours before scrutinizing the spot. If you observe it still darker than the rest of the floor, go ahead to re-apply a second coat.

Fifth Step 

You must make sure the bleach stays for 24 hours so it can evaporate and get the floor to dry. If you accidentally lighten the floor in excess, ensure to use a wood stain that fits the floor to restore the color.

Sixth Step 

Once the color is appropriate, and the floor is totally dry, apply a protective layer of wood. Unless you are refinishing the whole wooden floor, you should choose the same type of coating that will remain on the other part of the wood.

How To Remove Black Stains in Wood Using Oxalic Acid

When wood is exposed to water or metal for long, it causes dark spots on the wood. This is known as Iron oxide stains. Iron oxide chemically combines with the tannins in the wood and turns it black. In the same vein, you can paint wood black in a process called ebonizing.

Materials and Supplies needed

  • Water
  • Bar Keeper’s Friend orPowdered metal polish containing Oxalic Acid (Red Bear, etc.)
  • Paper Towels
  • Plastic Paint Scraper
  • Stiff Nylon Brush (optional)
  • Chip Brush (optional)

Below are the steps to remove black stains in wood surface using oxalic acid:

  • Evaluate The Stain

When wood is exposed to water, the stain is likely dark or almost black. On the other hand, if you observe the stain is dark red, that is most likely from food, wine, or something else.

This method is most important for the removal of dark iron oxide stains. And the good thing is that it will not cost a thing to try. Furthermore, If the wood material comes with a polyurethane finish or other surface coating, examine it properly. 

Also, if it is stained underneath, then that coating should be removed first. If the part has an oil finish, or if it is bare wood, you don’t need to do anything to prepare the surface.

  • Use Bar Keeper’s Friend And Water To Make A Paste

Ensure a little quantity of water should be added to the bar keeper’s friend until it attains a consistency that you can work with. The proportions aren’t necessary, but avoid making it to be too wet. Excess water only allows the grain to grow. Hence it should not be soaked. What is essential is for the paste to settle on the surface of the wood.

  • Endeavor To Wipe It On

Always test in a small, inconspicuous region. There should be no ill effects, but it is good to know if this is the case in a small area rather than the entire surface. Aim for stains the first time you use it. Clean or brush it and wait for it to dry within 15 to 30 minutes or above. You would see that as it is getting dried, the white paste will turn slightly yellow. This is a good sign.

  • Ensure You Scrape It Off

Ensure you scraped off the dry mixture and vacuumed it instead of wetting the surface and wasting paper towels. After the first application, you will see a big difference. If not, then this method will probably not work on the stain.

  • Rinse And Repeat The Steps Above

You should mix another batch and apply it in the same way as before. When most of the stains are gone, you will notice that the area you have cleaned will be lighter than the other regions. Next, apply the mixture to the whole surface of the piece to match it.

It is noteworthy that it only requires three applications for the stains to reach a point where you may not care about it anymore. A further application will remove the stain altogether. 

Here are additional tips to follow:

  • Avoid sanding very deeply during the sanding process. Once you start cutting further into the surface, more stains would be exposed. And then you will have to reapply the oxalic acid.
  • Since oak wood has a very open grain, a large part of the mixture remains stuck in the grain of the wood. It requires a stiff nylon brush moved in a circular motion to remove it. This is probably not necessary with other types of wood.
  • If your refinishing process involves steel wool, take extra care to remove any metal filings from the surface, especially with oak. It is recommended that you use brass wool or synthetic wool. 
  • In the future, if the metal particles get wet, it means you are back to the starting point with the whole staining process. Hence you have to repeat it.
  • In practice, steel wool is acceptable. Just blow off the piece with compressed air and buff it with a microfiber to remove any chips.

Frequently Asked Questions

How do you get black stains out of hardwood floors?

Hydrogen peroxide is also ideal for removing the dark stains and lingering odor on wooden floors. Soak a piece of fabric in hydrogen peroxide and place it over the stain overnight or at least 8 hours a day. Repeat this process for longer hours if the stain persists.

What causes wood floor discoloration?

Exposure to light is often the leading cause of discoloration on wooden floors. This could be as a result of UV rays exposure or exposure to light given-off by light bulbs or fluorescent bulbs. Another cause of discoloration on the wood floor is exposed to water.

Is black mold on wood dangerous?

There is no evidence showing it is toxic to humans or other living organisms. The most common black mold is Cladosporium, which has no known harmful side effects. This type of mold is common both indoors and outdoors. However, intense exposure to black mold can lead to increased symptoms of allergies and asthma.


To wrap up, you must understand that wood is a beautiful material. Therefore it is definitely worth the maintenance it takes. You should protect your wooden surface by never leaving wet objects on it. Clean off any spilled water, greasy or non-greasy substances as quickly as possible.

Also, make sure your pets are potty trained before moving freely on the floor. Pet urine stains are almost impossible to remove, and the associated odor can be very unpleasant. Once this penetrates the Wooden surface, it is tough to remove