How To Apply Polyurethane To Wood For The Best Results

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In my many years of working with wooden furniture and floors, I’ve found that polyurethane is one of the best sealer and coating substances. It preserves the finish of your chosen wooden design and allows it to ward off rust and rot.

One of the most efficient ways to give a wooden surface its beautiful luster and protected finish is by using polyurethane. For a gorgeous shine and long-lasting protection, applying polyurethane after staining wood is necessary. 

Since polyurethane is water-resistant and exceptionally durable, it has replaced varnish and shellac as a wood finishing material. 

And when you’ve spent such a long time deciding on your wooden floors and furniture, it’s only fair that you also get to choose the type of finish you want.

What Are The Different Types Of Polyurethane?

Primarily, there are 2 main types of polyurethane, water-based and oil-based. The stark difference is always in its color. Water-based polyurethane is a clear liquid that remains transparent over time, while an oil-based polyurethane application coating has a yellow tint that increases the hue of the wood after drying. 

Another difference between the two is the type of finish it provides. A water-based polyurethane tends to react with the wooden surface and requires more coats to achieve the desired finish, and because of this, it is adversely affected by chemicals and heat. So, in my opinion, it makes sense to choose an oil-based polyurethane finish if you live in a temperate environment and the color is not of much importance.

But water-based polyurethanes are great for floors because they have a weaker odor, are easy to apply, and are cost-effective.

So, all in all, both bases are excellent choices depending on what you need.

Choose Your Finish

Once you know the type of polyurethane you want to use, choosing the perfect finish is the next step. The different types of finishes determine the level of sheen.

  • Matte Polyurethane has the lowest sheen finish with no light reflecting off its surface, which is great for hiding smudges, scruffs, and other imperfections.
  • Satin Polyurethane is shinier than a matte finish but still on the low spectrum. This is one of the most popular choices among customers because of its easy maintenance and versatility.
  • Semi-Gloss Polyurethane requires more maintenance and ranks higher than the satin finish in shine. 
  • High-Gloss Polyurethane is one of the shiniest finishes and isn’t commonly used in homes because it makes imperfections highly visible.

Tools Needed To Apply Polyurethane

The method of application of polyurethane is very important to ensure precision and a desirable finish. The materials you’ll need include:

  • Sanding block
  • Automotive polishing compound
  • Lint-free cloth 
  • Oil-based polyurethane
  • Tack cloth
  • Rubber gloves
  • Utility knife
  • Bristle Brush or foam brush
  • Sandpaper (wet and dry)
  • Automotive rubbing compound
  • Mineral spirits

Patch Testing Before Application

Select a small area to patch test before you jump right into finishing your floors or furniture. That way, not only will you be sure about the results, but you’ll also be able to change the type of finish depending on the results you get. 

How to perform a polyurethane patch test:

  1. Designate a small patch of floor to test your polyurethane finish on (about 4-square inches will do).
  2. Use a wood cleaner to clean the area so it’s free to dust or any smudges.
  3. Lightly sand the 4-inch area with your grit sandpaper and wipe away any dust or residue left.
  4. Apply polyurethane to the patch test area and wait for at least 24 hours.
  5. Check the finish once the day has passed. It should be smooth without ripples and shouldn’t peel or scratch off when you rub a coin against it with moderate pressure.

How To Apply Polyurethane 

Now that you’ve patch tested and are happy with the results, we can start with our main finishing process. Let me take you through the best way to apply polyurethane to stained wood, step by step.

(Note that if you need to stain your wooden piece to a darker color, you must do that before sealing it in with polyurethane.)

Step 1

  • Before you dip your brushes into the polyurethane, you need to prep your wood first. Since polyurethane is essentially a plastic material, it accentuates any inconsistencies or surface imperfections. Before applying, make sure to sand the wooden surface that you want to seal properly.
  • Sand the area till it’s perfect for the finish. For better results, sand with a 100 grit medium sandpaper followed by a 150 and a 220 grit sandpaper for the most refined finish. 

Step 2

  • Once the wooden piece is free of blemishes, remove the remaining dust and debris from the surface with the help of a tack cloth.

Step 3

  • Now it’s time to prepare the sealant by thinning out your oil-based polyurethane by pouring 2 parts polyurethane and 1 part mineral spirit into a bucket. 
  • Mix them with a wooden stick until they form a homogenous mixture. 

Step 4

  • Apply the sealer with a natural bristle brush in even long strokes. I recommend using a brush with natural bristles because synthetic ones can cause air bubbles that are difficult to get rid of.
  • Coat the edges evenly and catch any drips with the ends of your brush to make the surface smooth.
  • Once you’re done, wait 24 hours for it to dry.

Step 5

  • After your first coat has dried evenly, it’s time to apply a second coat. Repeat the same process as the first coat and use long even strokes.
  •  Let it dry again for 24 hours.

Step 6

  • Once your second coat is dry, it’s time to perfect the application by lightly sanding or shaving off any polyurethane bumps and imperfections. 
  • Dampen the tack cloth with water and use a rubbing compound in circular motions that’ll help remove any scratches.
  • Once dry, wipe the surface with a dry cloth.
  • Usually, 2 coats for an oil-based polyurethane is enough, but if you want to add more shine, wait a few days and polish the wooden surface with a polishing compound instead of going for a third coat. 
  • If you’re using water-based polyurethane, you may need to apply multiple coats to get the results you want, but thankfully, they dry pretty quickly for it not to become a week-long process.


What Is The Best Way To Apply Polyurethane To Wood?

The best way to apply polyurethane to wood is by using a brush with natural bristles in long, even strokes. Remember to keep the application thin and avoid rubbing the brush against the can to prevent air bubbles. Let the first coat dry off completely before applying the next one.

How Do I Get A Smooth Finish With Polyurethane?

The most effective way to get a smooth finish with polyurethane is to dry sand your final coat. The second way is to use a combination of wet and dry sanding and mineral spirits. You can also use a polishing compound at the end.

Can I Apply Polyurethane Directly To Wood?

Polyurethane can be applied directly onto a wooden surface but make sure to clean, sand, and dust off the surface for a smoother and cleaner finish.

Applying Polyurethane for Your Wood Floor

I hope this guide was informative and helped you make the right choice for your wooden furniture and floorings. You’ll be done before you know it if you follow the instructions above. Just remember to have fun with it and let us know how it goes in the comment section below!

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Joe McGuinty
I’ve been working with floors for over 12 years. I started as a flooring contractor, primarily in materials selection. Then, I switched careers into accounting, so my wife and I began buying, renovating, and re-selling homes on the side. You’d be surprised how much value you can add to a home simply by adding new floors.

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