How To Remove Dark Stains From Wood

by Alex I on Dec 06, 2022

How To Remove Dark Stains From Wood

Remember that potted plant that has been sitting on your table for months? Or the water you spilled when picking up the jug? Or maybe the hot cup you put on the table?

Do you also remember the stains they left that you just never got around to working on?

Well, today is the day. You can easily follow the instructions given in this article and get rid of the stains on your wooden floors and furniture.

Let’s be honest; there’s nothing more annoying than the random stains that ruin the look of your perfect wooden furniture and floor. We list several methods here that can make your wood household items look as good as new.

What Do The Dark Stains On Wood Mean?

If there’s a dark, almost black stain on your wooden surfaces, it is likely from prolonged water exposure.

The liquid may penetrate through the wax or polish on the surface and get into the wood finish. That gives rise to tiny cracks in the wood. To remove the dark stains, you will need to reach underneath the surface. You can do that by stripping the wood finish using oxalic crystals, wood bleach, or hydrogen peroxide.

Although it takes some effort to remove these stains altogether, the actual process is simple and doesn’t take any more than a day or two.

There are several methods to remove dark stains from wood effectively. You may have to try more than one of the ways and see what works best for you.

Naturally, the quicker you get around working on the stain, the easier it is to remove it altogether.

Removing Dark Stains From Wood

Wooden floors and furniture certainly give a great look to your home, but they’re also very vulnerable to stains. Dark stains are one of the hardest to remove from wooden surfaces. That is because dark stains are soaked into the wood, and many of them need chemical reactions to come off.

Before you get started

Any of the products you use to remove dark stains from wood will have chemical ingredients. Before you use the given methods, test the product on a small area. That will make sure that the wood isn’t resistant to the product.

1.    Using Oxalic Acid Crystals

Here are the steps you need to follow to remove dark stains from wood using oxalic acid crystals effectively:

  1. Thoroughly clean the surface so that it is dry and clear. Make sure there is no residue on the surface where the product is to be applied.
  2. Dissolve Oxalic Acid Crystals in hot water to make a saturated solution.
  3. Use a brush to place the molten oxalic acid onto the stain.
  4. Let the liquid dry on top of the stain. That generally takes around 20-25 minutes.
  5. Once it looks powdery, thoroughly rinse the area with clear water and leave it to dry.
  6. When the surface is completely dry, lightly sand the surface to blend the color.

Expert Tip:

Do not use the Oxalic Acid Crystal solution while it is too wet. Applying the solution in that form will cause excess water to seep into the surface and raise wood grain. The solution should be consistent enough to stick to the surface instead of being soaked into the wood grain.

2.    Bleach the Stain

When it comes to using bleach for removing dark stains from wood, there are two options to choose from. You can either use household bleach or wood bleach especially designed to remove dark stains from wood.

Household bleach is sufficient if the stain only covers a small area, but wood bleach would be a better choice if you want to use it for an enormous stain.

You can use the process of using bleach to remove dark stains for both finished and unfinished behavior. You need to be very careful when using bleach because of its irritant components.

Here are the steps you can follow to apply bleach and remove dark stains from wood:

  1. Apply a small amount of bleach on a toothbrush. Make sure that the toothbrush is clean and unused. Alternatively, you can also use a small paintbrush for this method.
  2. Scrub the toothbrush onto the stain in a circular motion
  3. Once the stained area is covered with bleach, leave it to dry.
  4. You will need 2-3 coats, depending on the severity of the stain.
  5. It will take a few hours for the bleach to set in and lift the stain.
  6. Once the bleach is dry, take a wet sponge and wipe the stained area.
  7. If required, you can neutralize the bleach by soaking the stain in vinegar and water.
  8. Carefully wipe off all bleach residue to make sure it doesn’t damage the wood.
  9. You will notice that the stained area is now lighter. Repeat the process 2-3 times to remove the stain altogether.
  10. When the process is complete, dry the wood thoroughly.
  11. Then sand the whole piece’s surface to make sure the bleached area blends in with the rest of the wood.

Expert Tip:

If the stain doesn’t improve even after multiple applications, you can use the following method.

3.    Sand the Stain

If you have tried either or both of the above methods, wash the wood thoroughly before starting. That is done to eliminate any chemical residue left behind on the stain.

You can soak a wet sponge with dish soap and simply scrub the wooden surface. Then rinse and dry the wood to remove the effects of the chemical treatment on the area.

Here are the steps you can use to effectively sand and refinish the stained area:

  1. First of all, strip off the wood finish over the stain. You can use sandpaper to remove the wood finish.
  2. Continue to remove the wood finish until you reach bare wood.
  3. If there are many stains that you have to work on, it would be better to use a sanding belt or an electric sander.
  4. When you get to the bare wood on the surface, you can start sanding the stain directly.
  5. Continue to sand the area until you can remove the whole stain.
  6. Once done, use a wet sponge to wipe off the surface of the material.
  7. If you notice any holes or cracks in the wood, you can fill them with wood putty. We recommend using the Osmo Wood Filler for the best results.
  8. When the wood putty dries, sand the surface till it is smooth again.

Expert Tip:

When you sand the surface, be careful with the force you exert. If you grind too deep and cut down into the surface, the stained area might become exposed once again.

Refinish the Wood

The last step in removing dark stains from wood is to refinish the stained area. That is done because the processes for stain removal often leave the site lighter than the rest.

Before you start refinishing the wood, ensure that the surface is clean and dry with no residue present. If there is moisture present on the surface, it can result in difficulty to adhere.

The Osmo Wood Finish Transparent has a range of colors available to help you try and match the wood finish with the wood’s original color. That allows you to have a uniform surface and maintains the look of your wooden floors and surfaces.


Dark stains are hard to remove from wood because the moisture has penetrated the finish and seeped into the wood. However, you can make the process much more convenient for yourself by using the right products and following the given instructions.

Several methods are provided to work your way around it and see what’s most effective for you. With the proper techniques, you will be able to remove dark stains from wood in no time.

For more products, you can visit our store.