Oil Based and Water Based Polyurethane? Which one is Right for my Project

When standing in the polyurethane aisle on your third trip to the hardware store while doing your DIY project you may have asked yourself “What is the difference between oil based vs. water based polyurethane?”, is that just me? What I usually do is just buy the cheapest one and move on. But a few ruined projects later I have learned the lesson. there is actually a huge difference between oil and water based poly’s. Both oil and water based polyurethanes provide a protective coat for your wood projects, protecting the wood from damage. Both oil and water based polyurethane have their strengths as well as their weaknesses. Here we will discuss them all.

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What is Polyurethane

Polyurethane, whether it is water based or oil based, is a super versatile coating that offers excellent protection to your wood surfaces while also enhancing the natural beauty of the wood grains. Unlike the other popular wood finishes such as varnishes, shellacs, and lacquers, polyurethanes have one distinct advantage: they are essentially a form of durable plastic. This unique attribute ensures long lasting durability and resistance to wear and tear, making polyurethane an ideal choice for preserving and enhancing the appearance of your project’s wood finishes.

Pros and Cons of Water and Oil Based Polyurethanes

Appearance of Oil based and Water Based Polyurethane

When it comes to the appearance of water based and oil based polyurethanes, there’s a noticeable difference that can really affect the look of your project. Trust me, I learned the hard way! Oil based polyurethanes tend to have a richer, deeper hue, imparting a warm, amber tone to the wood – it’s really quite beautiful on the right piece. This means that oil based polys can turn your project yellow, which obviously is not desirable. On the other hand, water based polyurethanes when dried are clear, resulting in a more natural appearance of the wood grain. They won’t change the color of the wood, which can be perfect if you love the original shade of your project. So, you see, each has its own charm, and the choice between the two really depends on the aesthetic you are trying to achieve.

Polyurethane Durability

In terms of durability, I’ve found that oil-based polyurethanes usually outlast their water-based counterparts. This is because oil-based polyurethane penetrates deep into the wood and hardens to create a protective barrier that is extremely resistant to scratches, heat, and solvents. I’ve had furniture pieces finished with oil based poly that have withstood multiple years of heavy use, showing only minor signs of wear. Water based polyurethanes, though not as resilient, still offer a decent level of protection and are more than sufficient for most projects that won’t be subjected to heavy wear and tear. So, while durability might be better with oil based polyurethane, don’t sleep on water based options they could ultimately be a better choice if you are working on a project that will see only minor wear and tear.

Application of Oil Based and Water Based Polyurethanes

The application process and how you do it might be the most important part of the finishing work of your DIY. When it comes to application, each type of polyurethane has its quirks. Applying oil based polyurethane can be somewhat trickier. It’s usually thicker in consistency, which can make it a bit of a challenge to get a smooth, even coat. Now, water-based polyurethane is thinner making the application process easier and quicker. One important thing to remember is to always apply in a well-ventilated area, but particularly when using oil-based polyurethane, as it has a stronger odor.

Drying time

Oil based poly has a much longer drying time than water based poly, so you’ll need to be patient! On the upside, longer drying times also mean longer work times meaning you don’t have to rush through the application process, which can be a blessing. Water based polyurethane like we mentioned earlier is much much thinner and dries really fast so working fast is a must to get a nice even and error free coat. Weather also impacts drying time in dry hot areas drying speeds up and in colder and more humid climates drying time is drawn out. One trick I have learned is to use a scrap piece of wood from your project to test the drying time and to get a feel for the application process.

Thickness

Since oil based is a thicker product it tends to go on thicker, which means that it may require fewer coats, but fewer coats come with the challenge of trying to achieve a smooth and even finish. Likewise since water based polyurethane is a much thinner consistency it will require more coats to achieve the same level of protection. But, it’s easier to work with and allows for a quicker layering process. My advice here is to consider your project’s needs and intended use as well as your comfort with the application process before deciding on the thickness of your polyurethane. In reality, for me this always comes down to a game time decision and what I have the patience, energy, and time for.

Texture

Some people say that water based polyurethane is a rougher finish and doesn’t feel as smooth as an oil based polyurethane does when they are both dried. I have applied both versions of polyurethane more than a few times, and both honestly feel the same to me. A trick I have learned is to lightly sand the project with a high grit sandpaper in between coats of polyurethane and thoroughly wipe the project down (to remove the dust and debris). This extra step has always ensured us a nice and smooth finish on all our wood projects.

Cost

A quick search on a few large hardware store websites showed that oil based polyurethanes are actually a third of the cost of the water based polyurethanes. This actually surprised me a little bit since I would have assumed that water based poly’s would be cheaper due to them being primarily water. I would guess that since the water based poly’s are more popular the stores can get away with the higher price and so they do.

Finish

Just like paints polyurethanes have finishes too. The main ones you will see with polyurethane are Satin, semi gloss, and matte. Satin finish much like its paint finish counterpart is likely the most popular finish due to its versatility and ease of maintenance. Semi gloss finish on the other hand will require more maintenance than a satin finish when dry though semi gloss is clear and shiny making it a perfect choice for flooring or other wood items you want to add a bit of shine to. A matte finish has the lowest sheen (shine) available. This finish reflects no light creating a flat and somewhat dull appearance. A matte finish makes it easy to hide scuffs, small dents, and other surface flaws.

Selecting Water or Oil Based Polyurethanes?

And now the answer to your most pressing question. Which one do I use for my project. Unfortunately, I can’t answer that question for you since there are so many variables to take into consideration. What is the intended use of the wood piece? What is the outside temperature? What is your budget? these questions and countless others will all lead you to the right decision for your project.

Now that you are up to speed on the differences between oil and water based polyurethanes learn all about the differences between oil and water based wood stains.

Water vs Oil Based Polyurethanes: Conclusion

The choice between water based and oil based polyurethane largely comes down to your unique project needs and personal preferences. I’ve used both types in various scenarios and found that each serves its own unique purpose. Oil based polyurethane finish, with its durability and rich finish, has been my go to for heavy duty projects. The ease of application and quick drying time of water based polyurethane finish has been a lifesaver for quick weekend projects and projects that will experience minimal. Keep in mind that the ultimate goal is to enhance and protect your hard work and both versions of polyurethane do just that.