Why is my Wood Floor Turning Black [Causes and Remedies]

Black stains on your wood floor are a serious cause for alarm. They can lower your home’s resale value, ruin the interior aesthetics, and even indicate a critical health concern in cases of mold. 

Understanding the cause of these stains on your floors is the first step to removing them and forestalling further damage. So, why is my wood floor turning black?

Stay with me to learn the causes and potential remedies to black spots on your floor.

Also Read:

  1. Best Wall Color for Gray Floors 
  2. Best Upholstery Cleaner for Pet Urine 
  3. How to Fix Warped Wood Floor 

Why is my wood floor turning black

(Causes and how to remove them)

Dark spots are one of the most common problems homeowners with hardwood floors face. To remove the dark stains effectively, you must determine what caused them. Some of the popular culprits are:

Moisture Stains

Water damage on wood floors may result from several factors, including topical moisture, plumbing leaks, and indoor plants pooling water. Tannic acid, which is present in some wood species, is water-soluble and may cause discoloration when in contact with water and iron. The resulting discolored spots look like lightly charred wood. 

Black moisture stains in wood indicate that the moisture has penetrated deeper layers of the wood and will require a lot more work to remove.

Iron Stains

Iron stains usually appear as small, black specks on the wood surface. They form because of the chemical reaction between iron, wood tannins, and water.

These dark spots may also form from the residuals of specific abrasives left on the floor that react with water.

Chemical Stains

These irregularly shaped discolorations on areas of a finished floor result from reactive chemicals. These chemicals that spill on your floors can react with the wood material and cause stains.

Some of the most common causes of chemical stains include household cleaning products, pet urine, and reactive bleaches and conditioners applied during the coloring process. Other household products that can react with wood on your floor include oil, chlorine, acetic acid, acetone, or even milk.


Removing the chemical stains from your hardwood floor may require regular detergents and cold water. The two are particularly handy when dealing with ink spills or pet urine. Also, you will significantly benefit from this mixture when dealing with the chemical stains while they are still on the surface.

The below process is imperative when removing chemical stains in hardwood floors using detergents.

Step 1: Using a bowl, mix cold water with regular detergent.

Step 2: Identify the stained area and apply the mixture using a soft rag. You do not want to leave any stain traces and would want to cover the affected area with the mixture.

Step 3: Wipe off the stain. You can slightly apply pressure in the process but ensure you have not damaged your hardwood floors. Notice the changes in the stained areas.

Step 4: You can repeat the first three steps if the stain is not fully removed. Ensure you are not using the same cloth as you can restain the already cleaned areas. Repeat the process until the whole stain is removed.


Mold infestation is another common cause of wood floors turning black. When water pools under your floor’s surface, it encourages mold growth, which usually appears as dark/black staining.

If the black mold is noticeable on your floors’ surface, this typically indicates that the infestation is at an advanced stage.

Sap Stains

The wood that makes your floor can sometimes breed fungus inside them. Sap stains describe the discolorations that result from fungi of the Acomycetes or the Fungi imperfecti (Deuteromycetes) groups growing on the wood’s surface or inside.

The growth of these fungi is fostered by the exposure of the wood material or timber to moisture. This discoloration may appear on your wood floor surface as brown, black, or blue spots and can make your floor lose its aesthetic appeal.


Removing the sap stains off your hardwood floor is pretty simple, and you may not need a professional. All you will need is a non-diluted oil soap such as Murphy’s. Use a sponge to apply the oil soap to the sap or affected area and let it rest for about 15-20 minutes.

The oil soap will soften the sap, enabling you to easily scrub off the dirt with a non-scratch sponge or brush. You will then need to rinse it off.

How to remove black stains on wood floors.

The cause of the black stains on your wood floors will help determine the cleaning materials and methods you can safely use to remove the stains without causing further damage.

Below are the two most effective ways to remove black stains from your wood floor.

  1. Bleach the black stains

Wood bleach is quite effective at removing black stains from wood floors. You can use it to remove surface blemishes and to lighten the stain in preparation for further restorative action.

Depending on the solution you use, you may need to wear protective gear and work in an area with proper ventilation.

You can use the following solutions to bleach wood following the illustrated processes. 

  • Hydrogen Peroxide: This is a powerful stain remover with excellent bleaching properties. It is great for removing black stains in wood caused by moisture, ink, or dirt. To remove stains, soak a cloth in hydrogen peroxide and leave it on the stained area for up to eight hours. Allow the spot to dry after removing the cloth, and repeat the process as needed.
  • Chlorine: Chlorine removes food and blood stains and acts as a weak bleach. To use this solution, start by wearing protective gear and ensuring that the room you are working in has proper ventilation. Apply chlorine directly to the stained area and scrub using a cloth or scrub brush as you wipe away the excess solution. Allow the surface to dry and wash with clean water afterward.
  • Vinegar: This natural cleaning agent can be used to remove dark spots, stubborn ink and dirt stains, and strong odors. Mix a cup of white vinegar into a bucket of warm water and use a cloth soaked in the mixture to rub the spot gently.
  • Baking Soda: Baking Soda is an excellent option for removing black stains caused by vomit, urine, mold, and other substances that cause a strong odor. Mix the baking soda with water or vinegar to make a paste and apply it to the stained area. Let the paste dry and clean the area with a clean dry cloth.
  • Oxalic acid: Oxalic acid is a cleaning agent that is ideal for removing set-in rust and water stains and lightening the graying effect in exposed wood. Mix the oxalic acid powder with water to make a paste and brush it over the stain. Leave it to soak for a few hours, then wipe it away and repeat the process until the stain is entirely removed. It is important to note that oxalic acid is highly toxic and should be handled carefully according to the manufacturer’s instructions.
  1. Sand and refinish the wood

If cleaning and bleaching products do not remove the dark stains, they are likely to have already penetrated the finish and set in. You will need to sand and refinish the wood to remove the stain.

Start by washing the wood to remove any chemical residue on the wood from previous treatments. Use a wet cloth and dish soap to clean the area around the stain, then rinse and dry the wood.

Get 100-grit sandpaper and sand the finish along the grain of the wood until you reach bare wood. You may need a belt or electric sander if the stain is over a large area. Once you reach bare wood, switch to a 150-grit sander, and sand along the wood’s grain until you have removed the stain. Afterward, vacuum-clean the wood dust and wipe the surface with a tack cloth to catch any straying dust.

After removing all the dark spots, it is time to stain and refinish the area. Find and apply a stain that matches the floor color using a rag and leave it for about half an hour. Wipe away the excess stain and apply the topcoat once the floor is dry.

How to get rid of black mold on hardwood floors

Mold grows in an environment where moisture, warmth, and food are present. Not only does it stain hardwood floors, it can also move below the surface to warp, discolor, and rot the wood.

Below is a comprehensive guide on removing black mold from hardwood floors.

Step 1: Pay attention to signs of mold under your floors

There are some tell-tale signs that you have a mold problem, as discussed below:

  • Symptoms of mold exposure- You may suffer from breathing problems, itchy eyes, headaches, and difficulty breathing.
  • Odor- Mold usually emits a gas that smells musty. This smell is a reasonably sure indicator that you have mold, even if it is not immediately visible. Black mold will usually smell like soil or rotting leaves.
  • Warped floors- Mold growing beneath the floors will eventually cause the floorboards to start warping and twisting.

Step 2: Personal Safety

Black mold is a health hazard, and therefore, it is imperative that you wear the proper personal protective equipment when working around it. If you are removing surface mold over a small area, safety glasses and gloves are enough. However, if you are removing ingrained black mold over a larger area, you will need to use a P-100 respirator or an N-95 mask on top of the glasses and gloves. 

Also, remember to wear clothes and shoes that you can wash or dispose of easily.

Step 3: Remove the surface mold

Cleaning minor, surface-level mold is relatively easy. You can use a commercial mold cleaner, a chlorine bleach solution, or a cleaner designed for use with urethane finishes. Spray the area with your bleach or cleaner solution, allow it to sit for ten minutes, then wipe it off with a rag. If the mold stains are stubborn, scrub the area with a firm-bristled hand brush, and then wipe it away. 

Tip: Do not allow the bleach or cleaning solution to spread to uninfected areas or leave it on the wood longer than necessary. This will help to preserve the wood’s finish. 

Step 4: Remove ingrained mold

By the time you notice warped or blackened floorboards, the mold will usually have already penetrated the wood grain. In this case, start by assessing the depth of the mold. Use a screwdriver or any sharp tool to press into the spot. If the wood is soft, the mold has likely spread below the wood’s surface and can be removed. However, if the wood crumbles or feels spongy, it may already be rotten, and you cannot salvage it.

Before removing the mold, you first need to eliminate all the moisture in the room. Ingrained mold must be dry before removal, which will also help prevent future mold growth. Set up a large fan and blow air directly toward the moldy floor for a few hours until completely dry. Since back mold particles are also dangerous to inhale, you should also ensure that you open all exterior doors and windows to provide sufficient ventilation.

After the surface is dry, sand off the finish so you can apply wood bleach. You may need to use a flooring sander if the damage is widespread. Then, apply a diluted bleach solution to the area, let it sit for some hours, and later wipe up the bleach solution with an old rag. Bleach will help to kill mold and spores before they spread.

If black spots remain after bleaching, use a saturated oxalic acid solution to treat the wood, then neutralize and rinse.

Step 5: Stain and refinish

After removing the mold, apply a finish that matches the color of the wood floor. However, repairs are sometimes tricky to blend, and you may need to sand and refinish the whole floor to get an even and consistent color.

The video below show how to remove black mold from hardwood floors

How to change the color of hardwood floors

Floor color significantly impacts a room’s design, feel, and aesthetic. Several options are available to you depending on factors such as the type of wood and the amount of effort you are willing to expend. Below is a discussion of some of these options.

  1. Refinishing

This is the best method to change your floor’s color. The standard procedure is to start by sanding your hardwood floor using a drum sander and the edges with a flooring edger. However, if the finish is just a little thick, you can use a less aggressive sanding method.

After you remove the old stain, apply the new color stain, leave your floorboards unstained, and finish the wood floors with two to three coats of a clear finish.

Tip: Your wood’s condition and the natural color of your hardwood may limit what you can accomplish. Thin and old hardwood would do better being replaced as it may not tolerate the sanding. Also, lighter woods such as oak will allow you to work with a broader color palette than darker hardwoods such as mahogany.

  1. Glazing

Glazing is an excellent option for homeowners who want to avoid going through the sanding process, which is expensive, time-consuming, and messy. Before applying the glaze, you need to prepare the surface. Do this by screening (sand the finish using a floor buffer that has a sanding screen) the floor. This process is less abrasive than using sandpaper and will be gentler on your floors. Apply your glaze evenly on the surface, and when it dries, follow it up with a few coats of clear finish to protect the surface.

Tip: Although glazing is a good temporary solution, it is incomparable with sanding and refinishing. Glazes sit on the surface, leaving unseemly patches of uneven colors when they wear off.

  1. Whitewashing

Whitewashing is a great way of brightening lighter wood. There are several products specifically engineered for whitewashing hardwood floors, however, you can also get impressive results with a homemade whitewash solution of water and white paint. This method gives the wood a softer look while allowing the wood’s character to shine through.

Tip: Whitewashing darker wood may make it look brown, gray, or an unappealing muddy color. 

How to remove hardwood floor

Although hardwood floors are highly durable, they are not indestructible. General wear and tear, mold, water damage, and structural issues are some of the main reasons you may want to remove your hardwood floor.

The guide below discusses the most efficient way to remove them without damaging your subflooring.

Step 1: Gather all the needed tools and materials

Having everything you need at hand will make the entire process faster and easier. The tools you will need include:

  • Pry bar
  • Circular saw
  • Saw blade
  • Sledgehammer
  • Vice finger grips
  • Nail claw 
  • Tarps
  • Tape

Besides these, you will also need a selection of personal protective gear to help you tackle the project safely. Use work gloves to protect your hands, respiratory gear to keep you from inhaling any mold and sawdust, protective eyewear, and knee pads, as you will likely spend a lot of time kneeling. You should also wear closed-toe shoes and long-sleeved clothing.

Step 2: Prepare the working area.

Start by mapping out exactly how much of the floor you plan to remove. You can use tape to mark the boundaries and make your removal more precise.

In addition, we also recommend covering your furniture, appliances, and fixtures using tarps to keep them from being coated in sawdust. Remove any sensitive electronics from the room, as the dust may damage internal components even when covered.

Step 3: Cut and Pry

If you do not intend to reuse or donate the wood, it would be significantly easier to cut it into small sections. Set your saw to less than your flooring’s thickness to avoid damaging your subfloor, then cut sections approximately 1 to 2 feet wide perpendicularly at intervals.

Wedge the prybar under a section of the cut flooring and pull back sharply to remove the board. Repeat this until you have removed all the boards.

Tip: Pry the boards up in the direction they were nailed down in to prevent splintering and cracking. If the floorboards are too rigidly attached, strike their underside where they meet the subfloor to cause separation.

Step 4: Remove the nails and other fasteners

After removing the boards, you must clear up the nails, staples, and other materials used to secure the wood. You can use your nail claw to remove leftover nails and the curved vice grips to pull out broken nails. 

Step 5: Finish cleaning up.

Sweep and vacuum up the wood chips, sawdust, and other leftover debris. Ensure you have a lined garbage bin next to you to hold all the unsalvageable debris and wood.

Why is my wood floor turning black- Frequently Asked Questions 

Q1. Can you stain hardwood floor darker?

Yes, you can! However, the results will vary depending on the type of wood. It is easier to apply dark satin to lighter hardwoods such as oak and maple than to darker hardwoods such as walnut and mahogany. Some dark hardwoods also have natural oils that make getting a consistent and even look difficult.

Q2. How much does it cost to darken wood floors

Staining your hardwood floors a darker color will typically cost you between $1 and $3 per square foot, although the prices will vary depending on different factors. These factors are:

  •  The cost of the stain you use. High-end stains can go for up to $100 per gallon, while lower-end stains can average at about $30 per gallon.
  • The cost of labor where you live- Up to 80% of the project’s total cost may go towards labor costs.
  • The cost of the topcoat.

Some homeowners may undertake the project, which will offset the labor costs.

Q3. Should I stain my floors dark or light?

Dark floors in a home provide visual grounding, especially if the ceilings and walls are a light color. On the other hand, lightly stained floors bring airiness and brighten up a space. So how do you choose the best one for your home? Below are some factors to consider when making that decision.

  • Wear and tear: Although dark floors hide stains and defects more efficiently, they tend to show dents and scratches. This is because of gouges that go through the stained wood and show the undyed wood.
  • Design: Lightly stained floors easily match other color shades in the walls and furniture, while dark floors are more dramatic, create a sense of security and contrast with other bright elements.
  • Light: You should also consider the light your room receives before applying stain. Lighter floors can help brighten the space if the room is naturally darker. If the room is already bright, you can choose a more distinct dark floor.

Q4. Is it worth it to refinish hardwood floors?

While refinishing hardwood floors is not an innately complex process, it takes significant time and effort to get right. So, when is refinishing your hardwood floors worth it and when should you replace them instead?

Refinishing your floors when:

  • They have scrapes, gouges, and scratches. Sanding and refinishing your hardwood floor will make them look smoother and brighter without replacing them.
  • You want a cosmetic fix. Refinishing hardwood floors is the best option if you want to restore your floors’ shine and aesthetic appeal.
  • You want a change of color. If you want to give your floors a fresh look, refinishing and staining them a different color is an excellent option.

You can sand and refinish your floors several times during their lifetime. If the damages or changes are minor, refinishing your floors is worth it.

However, if your floors are structurally unstable or severely warped, replacing them would be a better choice.

Q5. How can I change the color of my hardwood floors without sanding?

If you do not want to go through the hassle of sanding, you can opt to glaze your floors. Although you do not need to remove the existing finish when glazing, you do need to prepare the surface. You can do this through a process called screening, where a sanding screen is fitted to a floor buffer and then used to sand. 

After screening, you can proceed to apply the glaze evenly. Finish the floors with around two coats of clear finish to protect them from wearing out quickly.

Q6. How do you get black water stains out of hardwood floors?

Black water stains typically indicate prolonged water damage. To remove them, spray a chlorine bleach solution over the affected areas to lighten the stain. This will cause the wood grain to rise to the surface and kill any mold growth that the water may have caused. Allow the solution to sit for about five minutes, then wipe away the excess.

With the stains on the bleached sections now lighter, you can sand down and refinish the floorboards.


Although the sight of black stains on your precious hardwood floor can be alarming, with quick and precise action, you can reverse the damage. In most non-severe cases, all you may need to do is bleach, sand and refinish your wood floors, to get them back to their beautiful, unblemished state.

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