What Causes Dark Spots on Hardwood Floors?

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Hardwood flooring is a great option for any home because of its aesthetic value. However, this material can easily be ruined when dark spots and discolorations appear on its surface. To find out how these unsightly marks can be removed, it’s important to determine the causes of these spots first.

So what are the dark spots that appear on hardwood floors? There are many reasons why discolorations may appear on the hardwood. They can develop because of sap stains, iron stains, tannic acid discoloration, sticker stains, chemical stains, black water and moisture stains, and a blotchy finish.

What Are the Dark Spots on the Hardwood Floors?

The value of North American hardwood flooring in 2019 reached $4.6 billion, showing that more and more homeowners are falling in love with this popular flooring material. Hardwood is an excellent flooring option with an extremely long lifespan. It also doesn’t need frequent replacement because the surface can be refinished a few times before it becomes too thin.

However, hardwood materials are still susceptible to scratches, stains, and warpage. One of the most common problems for homeowners who use hardwood floors is the appearance of dark spots on the surface. Here are some of the most common causes of these dark stains:

  • Sap Stains – Sap stains are the discolorations that are typically caused by a certain fungus growing inside the wood or on its surface. Standing and fallen timber are more susceptible to these fungi because it is when the conditions and moisture are prime for fungal growth. The discoloration may appear as brown or blue.
  • Iron Stains – Iron stains are small, discolored specks that appear on the surface of the wood. They are a result of the chemical reaction between iron, water, and wood tannins. These stains may appear when remnants of abrasive minerals were left on the hardwood before the water-based finish was applied.
  • Tannic Acid Discoloration – Tannic acid is a specific type of tannin found in trees. They are typically used to protect trees from bacteria and insects. Discoloration may occur if the high level of tannic acid forms a chemical reaction with the finishing material applied to the wood. Some of the wood species that have high tannin levels are mahogany, oak, and walnut.
  • Sticker Stains – When the wood boards are stacked during the seasoning process, they are separated using thin strips to allow the air to circulate properly. These thin strips (or stickers) may leave blue or brown stains on the hardwood boards. Since they cannot be removed through sanding, sticker stains are permissible in most hardwood floorings.
  • Chemical Stains – On the other hand, chemical stains are irregular-shaped and discolored spots on the hardwood’s surface. They may appear when chemicals are spilled on the material and react with the wood. Some of the most common household items that can cause chemical stains on the hardwood floors are acetone, oil, milk, chlorine, and acetic acid.
  • Black Water and Moisture Stains – The cardinal rule when it comes to taking care of hardwood floors is to protect them from water damage. High moisture content in the environment may leave black molds on the hardwood floors. Pet messes such as vomit, poop, and urine, also contribute to the appearance of black spots on the floor if they are not cleaned immediately.
  • Blotchy Finish – Blotchy stains are the inconsistent color of finished hardwood floors among different areas. They can happen if the wood itself doesn’t absorb the colorant evenly. Blotchy stains can also occur if the flooring contractor applies incompatible products, does a poor sand job, or fails to follow the finishing guidelines set by the manufacturer.

How to Eliminate the Dark Spots on the Hardwood Floors

When it comes to removing the dark spots on the hardwood floors, it’s important to know what caused these stains in the first place. This can help determine what kind of cleaning materials should be utilized to get rid of the stain without damaging the material further.

Always make sure to check the instructions on the product label before applying it on the hardwood floors. If you are unsure about the best way to remove the dark stain, it’s better to ask a professional woodworker or flooring contractor first. 

Here are two of the best ways to remove the dark spots on the hardwood floors:

Bleaching the Dark Spot 

Wood bleach is an effective solution that can eliminate black stains from the hardwood floors. They were developed to lighten the hardwood’s color and remove the blemishes found on its surface. While there are wood bleach brands available in the market, there are also a few homemade solutions that can work in getting rid of the dark spots, such as:

  • Chlorine – Bleaching agents made from chlorine are effective in removing food, blood, and ink stains.
  • White Vinegar – Aside from removing the stain on the floors, white vinegar can also help eliminate the odor of the hardwood floors. Just mix a cup of warm water with a cup of white vinegar to get rid of the dark spots. Scrub the stained area using a rug until the dark spot is gone, then pat the place dry.
  • Hydrogen Peroxide – Like white vinegar, hydrogen peroxide can also eliminate both stain and odor from hardwood. Soak a clean cloth on the chemical and place it on top of the stain. Leave the cloth there for at least 8 hours or until the stain is gone.
  • Baking Soda – This cleaning material is typically mixed with vinegar to create a paste. The mixture will be applied to the stained area and left to dry. Wipe the paste with a microfiber cloth when the black stain is gone.
  • Oxalic Acid – This acid is effective in eliminating rust and water stains in wood. It can also lighten the graying effect that occurs in exposed wood. However, oxalic acid is considered a highly toxic chemical. When utilizing this substance, make sure to follow the instructions and other safety practices.

Sanding and Refinishing the Hardwood

If the cleaning and staining products fail to remove the dark spots on the floors, there’s a huge chance that the damage has already set in and penetrated the finish. The best thing you can do to remove them is to sand and refinish the hardwood.

Fine grit sandpaper can be utilized to scrape the stained layer. Make sure to scratch in the wood grain’s direction when removing the stain. After scraping the surface, use a vacuum cleaner to remove the wood dust and clean up the area. Check the area to see if there are any parts of the stain left on the surface.

Once all the dark spots are gone, it’s time to stain and refinish the area. Find a stain that matches the floor’s color. Use two shades of stain and mix them to achieve accurate colors. Apply the stain on the hardwood floors using a rag and leave it for about 30 minutes.

Ensure that all excess staining solutions are wiped clean because they might leave behind awkward lines on the material. When the staining is done and the floor is completely dry, apply the topcoat with wax, wood varnish, or lacquer.

Durable Hardwood Flooring Options at Zothex Flooring

For the best flooring options, Zothex Flooring offers hardwood products that are manufactured from different species. We guarantee that all our high-quality hardwood products undergo strict inspection to ensure that they do not have unwanted stains.

Here at Zothex Flooring, we can help pick the right floors according to your preference and needs. Visit our website now to browse our hardwood flooring products.

Learn more: Maple VS Oak Flooring

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