How to apply polyurethane to floors? | Wood, Concrete, Plywood, Hardwood & Paint

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Did you ever wonder why polyurethane is important and how to apply polyurethane to different types of floors? Polyurethane is a kind of liquid that brings shine and gloss to the floor and makes it look so fresh and new.

Also, it works like a shield to protect your wood floor and makes it durable. Floors tend to get scratches, and after a few years, it starts looking less shiny. There are two types of liquid: open to making your wood floor look shiny and another one is to make it look matte. 

And you need to master your skills to get the perfect finishing on the floor. A new layer of polyurethane coat can protect your floor for 3-4 years. It means you just need to apply it on the floor once every 4 to 6 years!

In this article, we’ll give you the easiest way to apply polyurethane on wood surfaces. 

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Step by Step Process of Applying Polyurethane to Floors

How to apply polyurethane to wood floors? 

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Applying polyurethane on the wood floor without forming any bubbles requires plenty of time. Here are the steps of applying polyurethane on the wood floor:

Sanding the floor first

Here comes an important part of applying polyurethane on your wood surface. It prepares your wood floor to apply the coating so that it can contact the liquid smoothly. However, if you think buying a sander machine would be costly, you can always rent one (medium size). Make sure you dry your wood floor properly before sanding down the floor. 

Clean the wood surface

Now grab your vacuum cleaner and clean the floor by removing dust and particles from it. You must be careful while cleaning so that not a small hair is left on the floor. Make sure you clean the corners properly. It will help you to get a great finishing after applying polyurethane.

Once you are done vacuuming, clean the surface by using white vinegar. Then turn the fan on to dry the floor instead of opening the windows. However, if you are using water-based polyurethane, then you have to use a stain on the surface before applying the coatings. 

Mix Polyurethane

Before you apply polyurethane, mix them properly, it will make the coatings more durable. Use a big container and pour all the liquids into it. Now use a mixing stick and stir the liquids properly. Take your time and remove all the bubbles from it. Make sure you take a big container that can hold enough liquid to coat a whole room unless you want to mix liquids again in the middle of work.

Apply the first coat and let it dry

The first coat should be done very carefully and nicely without any bubbles and leaving the corners. Corners are hard to reach with a roller applicator, so use a bristle brush instead to apply polyurethane on the corners. Now use the roller applicator and apply the first evenly. We would suggest you leave the floor to dry for at least 4 hours. However, you can apply the next coat after 3 hours too. 

Apply the rest of the coats

Once your wood floor is dry, use 220-grit sandpaper for sanding the floor softly. After sanding the floor, clean the wood floor again with vacuum and white vinegar. Then apply the second coat and wait for 3 to 4 hours again. Repeat the process until you apply the last coat.

Watch this video to know more about how to apply polyurethane to wood floors:

How to apply polyurethane to Concrete Floors?

To apply polyurethane on the concrete floor, you need to follow the following steps:

Clean the concrete floor first

First, you need to mop the surface by using odorless mineral spirits. It will help the floor to dry quickly; thus, the applying polyurethane process becomes quicker. Use a fan to dry the floor quickly and keep it clean till you apply polyurethane. 

Mix Polyurethane properly

You may think about shaking the liquid to mix it, but it will only create more bubbles on the liquid. You can use a paint paddle or mixing stick to mix the liquid and remove all the bubbles from it. No need to rush the mixing process. Take your time and slowly stir it by pouring it on a big bucket or jar.

Start the applying process from the corners

First, pour a small amount of liquid on a corner; we would suggest using small brushes to evenly coat the corners. When you apply the polyurethane, make sure you work toward the exit so that you can come out from the room after applying it. Now use a roller applicator to evenly coat the concrete surface.

Let the coat dry

Here you should use a heater to dry it quickly. Make sure you do not step back on the surface where you have done coating the floor. Wait for around 4 hours before you start applying the next coat. 

Apply the second coat 

Do not walk over the floor without confirming that the floor is completely dry. Touch the floor gently near the wall and check if you can see your fingerprints over it. Follow the same process to apply the second coat to avoid bubbles and make sure you keep the pace slow. 

Apply the third and fourth coats

Follow the same steps to apply all the coats and make sure you give the floor enough time to dry properly. Before you put the furniture back, we would suggest you wait for a whole day or 24 hours to avoid any damage to the coatings. 

How to apply polyurethane to Plywood Floors
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How to apply polyurethane to Plywood Floors?

The following steps are what you need to follow to apply polyurethane on plywood floors:

Prepare the floor

To prepare the floor to apply polyurethane, you need to remove all the furniture from the room first. Now use sandpaper, and sand the whole floor and remove the previous coating properly. 

Clean the floor

Bring a vacuum; if you don’t have one, you can use a broom too. However, it will take much time to clean properly with a broom. Then mop the plywood floor to make it more clear so that you can evenly apply polyurethane.

Start applying the liquid from the corner

Mix the polyurethane liquid by gently stirring the liquid and get rid of all the bubbles. Now apply the liquid starting at the corners and edges. Then use a big applicator to quickly cover the whole floor with coating. 

Let it dry and then sand it again

Let the first coating dry for the amount of time mentioned in the polyurethane bottle label. However, the general time to wait is around 4 hours. Once the floor is dry, sand the surface again to get rid of bubbles and flatten the surface evenly.

Apply the last coatings 

Re-apply the coats, wait for them to dry, then sand them again. Use the same process of applying coats until the last coat of polyurethane you apply on the plywood floor.

What is the process of applying polyurethane on the Hardwood Floors?

Here are the steps of applying polyurethane to hardwood floor: 

Sand the floor 

To sand down your hardwood floor, use oscillating floor sanders to get rid of the previous existing coats. The sand should be near 220-grit, and make sure you remove all the coatings from the surface. However, if the hardwood surface is like an engineered wood floor, you can’t sand the floor with any sandpaper below 220 grit. 

Clean the surface

Use a vacuum cleaner to clean the surface without leaving any dust, debris, particles, even small and thin hair. Then use mineral spirits and mop the floor to double clean it. You will see how clean your floor is, and make sure you clean your feet after mopping the floor. Wear socks or stay barefoot after cleaning the sanded wood surface. 

Use paint tape walls 

Before applying the coat, make sure you cover the walls by using painting tape so that it doesn’t come in contact with the liquid. The same thing goes for the object that can’t be removed from the room.

Mix polyurethane 

Just like the other process of applying polyurethane, you need to mix the liquid here too. Pour the liquid into a big container and use a mixing tool to gently mix the liquid without forming bubbles. Never shake the liquid to mix it unless you want more bubbles on polyurethane.

Apply the first coat

Now it’s time to apply the liquid on the floor; make sure you start the applying process from the edges and corners. Use a lint-free bristle brush to evenly coat the surface there. Use a roller applicator as it makes the process easier to apply the liquid on the whole surface of the room. Let the surface dry properly before you apply the next coat, and it may take near 3-4 hours to fully dry the surface. 

Sand down the surface again before recoating 

Check the floor with your fingertip whether the coating has become dry and hard. Then gently use sandpaper to sand the floor to make it more even and clean. 

Apply the rest of the coatings 

Apply the same process of the first coat to re-apply the second coat and let it dry, then sand it again if necessary. Keep the working speed slow and gentle. 

How to apply polyurethane over Paint Floors?

The process of applying polyurethane on painted surfaces is a bit different from the above process. Here are the steps of applying polyurethane over the painted floor:

Wash And clean the painted floor

Remove grease and stain from the painted floor with the detergent solution if the painting is old. Bring a bucket full of warm water, then add 1/2 cup of trisodium phosphate to make a removal liquid. Then use a sponge to clean the floor properly. 

Sand the floor

Once your painted floor is dry, use 120grit sandpaper to flatten the sheen. Here you are not supposed to leave any deep scratch on the floor as it will remain visible under the coats. Then use any damp cloth to wipe out the dust coming from the sanding.

Choose proper applicator

In this process, you are not using a roller applicator; instead, use a brush or sprayer to apply the polyurethane on the painted surface. It will not create any kind of bubbles on the floor. However, if you are thinking about thinning polyurethane to spray it with a sprayer, then there is no need to do that. 

Apply the first coat and then sand the surface

This step is quite similar to the above steps. Check the label of your polyurethane bottle to know how long you will need to wait to let it dry after the first coat. Once it’s dry, sand down the floor to make it even and flat by using 120 grit sandpaper.

Apply the other coats

The process is the same. Make sure you wait for at least 24 hours before you bring back the furniture in the room.

Frequently Asked Question (FAQ)

What happens if you don’t sand properly between each layer of polyurethane?

Well, there is no significant or major impact on the finish if you don’t sand the floor between the coats. But the finishing of the polyurethane may look even and a bit bumpy. 

How many coats of polyurethane should you put on a wood floor?

Applying 2 coats of oil-based polyurethane and 4 coats of water-based polyurethane is enough. But if you need extra protection on the floor, use one more coat to make it thick.

How do you smooth the final coat of polyurethane?

It’s easy to make the final coat look smooth. All you need to do is sand the floor between the coatings and wait at least 24 hours to dry after the last coat.

Conclusion

You just learn the easiest way about how to apply polyurethane to floors and how to make them durable. The common step in all these applying processes is mixing the polyurethane liquid sanding down the surface for better finishing after each coat.

Getting a beautiful and nice finish, you must pay extra attention and be active while applying polyurethane. Also, you should not rush the process of applying for it. Moreover, make sure you give the floor enough time to dry.

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