Tag Archive for: black stains

Hardwood floors are known for being durable and resilient, but they have one big weakness: water.

Wood flooring can stand up to years of heavy use, but a little water over time can ruin the beautiful hardwood.

Maybe you moved into a house with a damaged wood floor or maybe you have had a flood from the kitchen or bathroom plumbing. If you are noticing stained or warped wood or big gaps between boards, you have water damage.

There are some ways that you can repair water damage you find on your hardwood floors, but sometimes you will need to replace the flooring altogether.

This guide will help you identify the type of damage, find out how to repair water-damaged hardwood floors, and teach you how to prevent future water damage.

How Can I Tell If I Have Water Damage on My Hardwood Floor?

If you recently had a small flood or water leak, you probably know that your wood floor has some water damage.

But if you’re not sure, you can inspect the floor visually for some of the signs of water-damaged flooring.

Wood Floor Staining

Water stains on a wood floor take the shape of an uneven ring that ripples across the wood from the water source. The stains can be either light or dark. Stains with a white outline are easier to repair at home than darker stains, which indicate a complete soaking of the hardwood floor.

Wood Floor Cupping

Cupping is one of the ways that hardwood flooring can warp out of shape when wet. You can identify cupping on your hardwood floor when the edges of the individual boards bend upward and are no longer even with the center part of the boards. It gets its name from the cup or bowl shape each plank takes when the edges rise up. Cupping can also make the gaps between floorboards expand, leaving uncomfortable cracks.

If you want to learn what to do about cupping on your hardwood floor, check out our article on cupping in hardwood floors.

Wood floor crowning

Wood Floor Crowning

Crowning occurs in a similar way to cupping, except the boards warp the opposite way. Crowning floorboards rise up in the middle, creating a bowed or bumpy appearance on each individual board. This is due to the floor pieces expanding and pressing into each other too much. Once the floor dries, it may leave large gaps between pieces.

Wood Floor Buckling

Buckling in wood floors

Buckling is the most extreme type of hardwood water damage. This is when the floor planks are pushed so tightly together that they actually detach from the subfloor. The extreme moisture in the wood causes each floorboard to expand. This can make a large hump in the floor or break the locking tongue-and-groove systems between boards.

Buckling is most likely if your hardwood flooring was installed poorly to begin with or in an extreme flood (such as gallons of water pouring in from a hurricane or a burst pipe).

If you suspect your water damage is so bad that the hardwood floor is buckling, check out our article specifically on buckling wood flooring.

Should You Fix or Replace Water-Damaged Wood Floors?

Once you have water damage on your wood floor, you might wonder if you can get away with fixing the floor instead of paying to replace it. This is especially tempting if your water damage is only a small area of the room.

It may not be safe to live with a water-damaged floor if it was wet enough for mold and other bacteria to grow.

In cases of severe floods or a leak of tainted water (like sewer water), you probably need to replace the whole floor to be safe. These molds or bacteria can be extremely dangerous to live with. Plus, severe leaks can weaken the subfloor and other structural pieces of your home.

If you are concerned that your wood floor may be growing mold, read our article about how to remove mold on a hardwood floor.

If your water damage came from clean water and you are able to dry the floor out completely, you can think about fixing the floor instead.

The problem with fixing hardwood floors is that it can be difficult to match the finish on a repaired section with the original finish.

If the water damage is in an out-of-the-way place or if you can throw a rug over it to hide the difference, repairing it may be a good option. Or, if the hardwood is only in one room of your house, you may be able to refinish the entire floor so it comes out an even color.

Your choice will depend on safety and whether you want to live with a repaired area that may look different than the rest of the floor.

You might consider replacing a section of the hardwood floor with a cheaper and more durable material, like ceramic tile. This is especially common in front of an entry door. You can remove the damaged section of hardwood and install tiles with a neat transition rather than having a section of hardwood that was obviously repaired.

Identifying the Source of the Water

If you find water damage on your hardwood floor that wasn’t there before, you need to be sure where the water came from. The source of the water makes a big difference in the decision of whether you should fix or replace your floors because some water sources may carry harmful bacteria.

What to Do When You Can’t Find The Leak

Sometimes the source of water damage is not obvious. You will want to fix problems before you fix the hardwood flooring so that you don’t have the same damage again on your newly repaired floor.

You can usually narrow water damage in a home down to two categories: external water sources and internal water sources.

External water sources dampen your home through the walls, roof, or foundation. Common external sources include:

  • Overwhelming amounts of water from a storm or flood
  • Overwatering a yard
  • Doors and windows with leaky seals, or that are left open
  • A leaking roof
  • A cracked foundation or inadequate or broken drainage system (sump pump)

Internal water sources come from inside the house. Some common leaks include:

  • Broken plumbing seals, such as radiator pipes or drains under a sink
  • Leaking pipes inside a wall or floor (especially if the pipes have frozen)
  • Failing hot water heaters
  • Soft hoses such as the water supply on a refrigerator or dishwasher (these often get pinched when moving appliances and should be replaced every few years)
  • Overflow from a sink or shower
  • A spilled mop bucket or mopping with too much water

These examples can probably help you find the source of the leak so it can be repaired. If you still have no idea where your water damage is coming from or you suspect it is coming from inside your walls, you probably need to call a plumber.

Is The Water Fresh or Dirty?

The water that stained your floor should fit into one of the following three groups:

  • Clean Water, such as rainwater from an open window, overflow from a sink or tub, or a leaking hot water heater. This water is mostly pure and will carry very few bacteria. Unless the area was wet for several days (enough for mold to grow), this kind of water damage is probably not dangerous.
  • Used or “Gray” Water, such as that from a drainpipe under a sink or shower, has been exposed to some dirt and other waste. If this kind of damage doesn’t dry quickly, it will grow bacteria and mold.
  • Dirty or “Black” Water is tainted water or sewage. This is from a leaking, overflowing, or backed-up septic line. This water is full of dangerous bacteria. You can try to sanitize the wood if it is only a minor leak (1 or 2 liters), but most of the time a black water leak will require replacing the floor. You should wear gloves and a filtering mask when you clean any area damaged by black water.

Identifying the source of the water damage will help you decide whether it’s safe to repair the floor. Of course, this is also the time to correct the problems that allowed water to get onto your floor such as by replacing window seals or calling a plumber to fix a pipe.

How to Fix Water-Damaged Wood Flooring

Depending on how much of the flooring was affected by water damage, you might need to call a professional to repair your water-damaged wood floors. They will be more experienced in sanding and staining the floor evenly. It can be a difficult process, but if you are confident in your DIY abilities, you should be able to pull it off.

After you get the floor completely dry and knock down the warped and water-damaged areas, the process is mostly the same as refinishing a worn-out floor. Feel free to read our other articles on that process, but we will include the steps here.

Step 1: Dry the Floor if it is Still Wet

If your water damage is new, you will need to dry the boards off before you can really assess the damage or make any repairs.

Standing water on the surface can be sucked up with a shop vacuum on wet mode. A squeegee can help push the water toward the vacuum hose.

Then the wood needs time to dry out internally. You can speed this process up by using fans and open windows to ventilate the room. You can also rent or buy a dehumidifier machine.

Be careful not to dry the floor too fast. Applying heat to a wet floor, for instance, can lead to more cupping or crowning. Hardwood needs to adjust gradually to temperature and humidity changes, so stick to natural airflow methods to dry the wood.

Step 2: Check for Extra Floorboards in Storage and Install Them

Usually, flooring installers will leave a few leftover pieces of wood at the house when they put in a floor. If the flooring in your house is decades old, you probably won’t have this luxury, but it doesn’t hurt to look.

A few pieces of flooring may be enough for a flooring installer to remove the damaged boards and replace them with new ones that will match perfectly. This is potentially the easiest way to repair your water-damaged floor, so look around.

Removing the old boards and laying new ones requires experience and the right tools. This is especially true if the wood floor is glued or nailed down. You most likely need a flooring expert to come to your house and replace the boards.

If the match on the finish is close after you install the new boards, this may be all you need to do. If the color difference is really bad, you will want to go on to the refinishing process.

Note that buffing and refinishing the floor will not only be more difficult, but more expensive. You will have to get the tools and supplies to refinish the floor.

Step 3: Sand the Floor

After you place new planks where the damaged ones were, or if you do not have any planks to weave into the floor, you are going to need to sand the flooring.

The right sander for the job is one that is specifically made for flooring. These have a large sanding wheel and a heavy head so that you can sand large areas quickly and evenly. You will probably need to rent it from a hardware store or flooring company.

Use a coarse grit sanding wheel first (around 60-80 grit) and follow with a fine sander (100-150 grit or a fine sanding screen).

You should sand the edges of the room by hand because it can be hard to maneuver the flooring sander into the edges and impossible to reach the corners. Use a fine sandpaper between 100 and 150 grit. Sand with the woodgrain.

If at all possible, you should sand the entire surface for the hardwood floor, or at least the entire room with water damage.

Move the sander across the entire surface of the floor, overlapping a few inches on each stroke. If you do not get the water-damaged sections flat on the first pass, you can try a second pass.

Do not sand the floor too many times unless you are sure that your planks are very thick. Taking too much thickness off the floor will cause problems.

Note: Wear a mask or respirator when using a flooring scuff sander. These machines will kick up a lot of dust as they sand the finish and wood.

Step 4: Clean the Sanded Hardwood Flooring

Use a vacuum to remove all of the sawdust you created by sanding the floor. Follow the vacuuming up with a dry microfiber cloth or dust mop. This will get the fine dust off of the floor.

This process will also remove other dirt and make the stain adhere better to the wood.

It’s good to do this not just after the sanding is complete, but every five minutes while you sand. 

You can also vacuum the sander wheel to remove the dust. If it clogs up too much, it won’t sand evenly. 

Step 5: Stain the Sanded Wood Floor

Following the directions on the can, apply the desired color of stain to the hardwood floor. Try to select a stain that is specifically made for hardwood floors.

Note that most wood stains will put off some strong fumes. You need to wear a respirator if possible, or at least ventilate the room by opening windows and using fans (not directly as they will dry out your stain too fast and blow dust around).

Start by applying a thin, even coat of stain to a small area (less than 1 square meter). Brush the edges and corners first to make sure you don’t miss them. Use a clean rag to wipe up all the excess wood stain.

You will have permanent lines in the finished coat if you let the leading edge of your stain dry. Try to work quickly and don’t leave any edge to dry for more than 10 or 15 minutes. Apply the stain evenly across the whole room.

Note: Make sure to have an exit strategy when you start staining. You don’t want to step across a wet stain to get out of a corner. Work from the deepest corners of the room toward the door.

Step 6: Apply Polyurethane

A coat of polyurethane on top of the stain will protect the floor from scuffs and create a water-resistant barrier.

You can roll polyurethane onto the floor like paint after the stain is completely dry.

The key to applying polyurethane is that you need a very thin, even coat to create a nice-looking finish. Choosing the right roller will help.

Don’t use a regular fuzzy paint roller or you will leave a coat that’s way too thick. Use a dense foam roller for a smooth finish. Also, use a long handle for the roller so you can see better while you work.

Cut in the edges of the room with a good quality paintbrush first and then use the roller to complete the center of the room.

Give the refinished floor a day to dry before moving furniture back into it and you will have a fully improved hardwood floor!

Preventing Water Damage to Your Hardwood Flooring

It’s always easier and cheaper to take care of problems before they become problems. Take care to avoid wood floor water damage in the first place.

Here are some ideas to prevent water damage to your hardwood flooring:

  • Keep doors and windows closed when you are away from home and repair small leaks as soon as you notice them.
  • Hire only licensed contractors to work on your plumbing.
  • Be especially careful of rubber or plastic hoses on washing machines, dishwashers, and refrigerators tha.t can break over time.
  • Invest in shower curtains, shoe mats, and other items to keep daily water off your floor.
  • When you clean your floor, do not bring a big bucket of mop water where it can spill on your hardwood floor and mop only with a small amount of water.
  • Clean up all spills immediately.
  • Keep your house warm enough to avoid freezing temperatures that can burst a pipe.

It’s possible that at some point in your wooden floor’s lifetime, you’ll encounter an area that has become darkened. This area might consist of a single, dark spot or there may be several spots or even several areas that have become discolored. The color might be a light greyish one, a deep, dark black color, or something in between. 

In this article, you’ll find answers to frequently asked questions related to the cause, removal, and prevention of black stains on wood floors. 

Is It “Normal” For A Wood Floor To Darken? 

This type of discoloration cannot be considered a “patina” of any sort as it is not part of any hardwood floor’s mellowing or aging process. Although it could be categorized as something that isn’t terribly unusual, this darkening is not normal. It is a stain and as such, it should be addressed. 

Why Are There Black Stains On My Wood Floor? 

If you weren’t on hand to actually witness the event or series of events that caused this, the cause is nevertheless evidence that an event has occurred. Dark stains indicate that a chemical reaction has taken place between the tannins in your wood floor and moisture or more specifically, the moisture’s level of acidity. 

If your hardwood floor shows no signs of warping, then the moisture is most likely to have come from above the floor rather than underneath it. 

Certain Types of Wood React More Profoundly Than Others

If your hardwood floors are:

  • Unsealed or
  • The seal has become worn
  • The wood has a high concentration of tannins
  • The grain of the wood is open

Then, depending on the acid content of the moisture it’s exposed to, it doesn’t take long for wood to become stained in this way. 

As with many hardwoods, their grain is one of the qualities that make them such natural choices among furniture makers. The grain’s detail and beauty are easily captured with a light application of stain or a mere rubbing of oil or bee’s wax. 

However, hardwoods contain higher levels of tannins. 

Proportional to the concentration of acids and minerals contained in the moisture, and the amount of tannins contained in the wood, the chemical reaction between them can be mild or quite profound. 

This Chemical Reaction Causes The Wood To Darken

Oak and walnut are particularly tannic hardwoods. Urine is a particularly acidic water based substance. The odor notwithstanding, the reaction between the tannic and uric acids is 

especially dramatic. 

All this makes it easy to imagine that a floor made entirely of hardwood could have several dark spots.  

If This Is The Case, Then There Really Is No Point In Crying Over Spilled Milk. Right?

Granted, by virtue of the fact that it can be so cathartic, crying certainly seems to have its therapeutic benefits. But because there continues to be a complete lack of evidence to suggest that crying can undo an event that has come to pass, the wisdom contained in the old adage also continues. 

As to its effect on a hardwood floor, it’s true that milk doesn’t contain uric acid. But milk does contain lactic acid. Lactic acid is ten times more acidic than acetic acid. If you think it will help you come to terms with it, then break out your crying towel because if it isn’t removed from your hardwood floor, even milk, whether spilled or intentionally applied, can cause the floor to darken. Harsh, I know, and not unlike urine, the smell is no picnic either. Sorry. 

Can Dark or Black Spots On Hardwood Floors Be Removed?

While the answer to this isn’t a 100% “Yes”, the outlook is certainly far from bleak. The odds for success are improved if you can answer “Yes” to the following:  

Have Offensive Odors Been Resolved? 

If there is a lingering odor, then whatever caused your floor to stain is still present. It’s possible for germs, bacteria and other unpleasantness as evidenced by the presence of odor, to be in residence underneath and in between the floorboards. 

Has The Moisture Been Resolved? 

Until the floor is completely dry, there isn’t much point in considering repair of the damage that not being completely dry caused. 

To Remove Dark Stains, You’ll Need To Remove The Cause

In other words, each of your hardwood floor’s boards needs to be thoroughly dry and odor needs to be treated. 

NOTE: This might entail removal of the undry boards. If you don’t have the skill or confidence to do this on your own, call your local flooring expert. If the expert is willing to remove the boards and then come back to install them once you’ve taken care of business, that’s even better. 

If your flooring expert suggests cleaning the boards with oxalic acid followed with borax, then do this. Follow his/her instructions to the letter. 

Otherwise, proceed with the following:

What You’ll Need To Remove Odor and Black Stains From Your Wood Floor

How To Get Those Smelly, Black Stains Out Of Your Wood Floor:

Remove The Floor’s Finish

  1. You’ll need to first strip the finish from the floorboards.
    1. to do this, be sure to follow the manufacturer’s instructions on the back of the container of the floor stripping product. 
    2. You can apply this with your paintbrush to be sure to keep the stripping solution contained to the affected area. 
    3. Use your plastic putty knife to scrape the lifted floor seal residue. 
    4. Use a clean rag to wipe and contain the residue from the putty knife. 
  2. Once your hardwood floor has been stripped, you might find the dark spots have lightened somewhat. This is to be expected. You’ll need to continue nevertheless. Especially if any odor is still present.

Remove Odor From Your Hardwood Floor

  1. Fill one of the spray bottles with the enzyme solution. Fill the other with hydrogen peroxide. Be sure to mark or label the spray bottles accordingly.
  2. Spray the affected area with enzyme solution. Be sure to spray in between the boards as well, but don’t drench the area or allow puddling. Allow the solution to dry. 
  3. Spray the area again with the enzyme solution. If after a few minutes, no odor is detected, pat the area dry. Otherwise allow the solution to dry.
  4. Repeat steps 5 and 6 as necessary.

Remove The Black Spots From Your Hardwood Floor

  1. Use your scrub brush to remove any residue from the affected area of your wood floor.
  2. Spray hydrogen peroxide well inside the area of the floor that has been stripped only. 
  3. Saturate a clean rag and lay it over the darkened area. Place another next to the first and continue until the entire darkened area is covered. 
  4. Cover the saturated rags with plastic wrap. Use a water jug or heavy book to keep the plastic in place.
  5. Allow the rags to remain in place up to eight (8) hours checking the rags occasionally to be sure they haven’t become too saturated with the stain to continue delivering the peroxide.
    1. Replace any stain-soaked rags with rags freshly saturated with peroxide.
    2. Replace the plastic wrap 
  6. When eight hours have passed, remove the soaked rags from the floor.
  7. When the floor has dried, the stain should be gone.
  8. If some discoloration remains, use the sandpaper.
    1. Working outward from the center of the discolored area, apply light pressure and smooth strokes that move in the direction of the grain of the wood.
    2. If the natural color of the wood doesn’t begin to appear after three or four strokes, move on to the next area and the next, sanding these in the same way and using three or four strokes in each of these areas as well. Sanding will help to expose the pores in the wood, but too much sanding will result in dipping this section of floor.
  9. Repeat steps 8-14.

By now, the stains should be completely gone. If any floorboards remain darkened, sand these lightly. if the discoloration still isn’t gone, they should be replaced. 

How To Prevent Black Stains On Hardwood Floors

The key to preventing black stains on your hardwood floor is in understanding that its exposure to moisture doesn’t need to be terribly prolonged to cause this. 

  • Clean spills right away
  • Follow up with an appropriate disinfectant. Be sure to follow the manufacturer’s instructions. 
  • If you have pets, be sure to inspect your home routinely for “accidents”. Use an enzyme solution to clean these right away as well. We even have a detailed guide on cleaning pet urine stains & smell from hardwood floors.
  • Routine inspection should include a check for leaks you might not be aware of. Look under the sinks, the washing machine, and the dishwasher especially. 
  • If you discover a leak, place a container underneath it to catch the water, and dry the area completely. Continue to empty and replace the container until the leak can be repaired.

By taking care of problems before they start, you’ll save yourself a lot of hassle, stress, and energy…

…which of course, translates to more beach time.