Last Updated on October 18, 2023 by Ernest Godia
Polyurethane is hands down the most durable finish for hardwood floors and other wood projects. However, not all polyurethanes are created equal. Some are water-based, while others are oil-based.
Both water-based and oil-based polys offer incredibly long-lasting protection to wood surfaces. However, the two polyurethane types differ in color, odor, and other characteristics that make them suitable for different needs.
Understanding the difference between the two polyurethane finishes should make choosing between them easier, depending on your needs.
Find out which option suits your needs better in the following discussion of water-based polyurethane vs oil-based polyurethane.
What is water-based polyurethane?
Water-based polyurethane is a liquid plastic product comprising water instead of solvents in its formula. The water in this product is the solvent equivalent or the vehicle that carries the polyurethane solids.
However, the product dries to form a tough, durable protective layer over wood, metal, and any item it is used on. This protective quality and glossy sheen are characteristics that water-based polyurethane shares with its oil-based cousin.
However, the number of layers applied to achieve the desired level of protection may differ between oil- and water-based polyurethane.
One of the greatest advantages of water-based polyurethane is its fast drying time. The product is also low in volatile organic compounds (VOCs), making it safer than oil-based poly.
The low-VOC profile means water-based polyurethane finishes have almost zero odor, so you can apply them without wearing a protective mask or respirator. You can also work with them without any problems, even if you are allergic to certain odors.
Water-based polyurethane pros and cons
- This polyurethane is easier to clean off surfaces and tools with mere soap and water.
- It has a completely clear color that remains clear over time, depending on the quality of the brand chosen. This is ideal if you want to preserve the wood’s natural appearance.
- It is fast drying, allowing you to finish applying it in less time.
- It is safe to use due to its low-VOC profile. This quality also makes it nearly odorless and friendlier to odor-sensitive users.
- Water-based poly may require more coats to form the desired durable protective coat.
- This type of polyurethane costs more than oil-based poly
- Some water-based polyurethanes go on so clear-colored that it becomes difficult to see where you have applied the sealant.
What is oil-based polyurethane?
Oil-based polyurethane is a liquid plastic that consists of mineral and petroleum solvents as the vehicle for the urethane solids.
These polys contain a higher percentage of solids, making them thicker. As such, you can achieve the desired level of protection and strength with fewer coats when using an oil-based polyurethane than a water-based product.
However, that thickness comes at a cost. Oil-based polyurethane takes more time to dry. The solvents in these products also mean a higher level of volatile organic compounds.
Therefore, an oil-based product will have a stronger odor that may be unfriendly to someone with allergies. They also produce fumes that are generally toxic to inhale, so you must protect yourself with a respirator or safety mask when using oil-based polys.
Oil-based polyurethanes also have a slightly yellow tint that they leave on the surfaces where you apply them.
The more coats applied, the deeper the tint. The protective coat also tends to turn yellow or amber over time. So if you want to retain the natural color of your wood, an oil-based topcoat may not be ideal.
Oil-based polyurethane pros and cons
- This type of polyurethane requires fewer coats, thanks to a higher percentage (45 to 50 percent) of solids.
- Some people prefer the slight golden tint of an oil-based poly.
- It is self-leveling, so any brush marks left will disappear on their own as the product dries.
- Oil-based poly costs half as much as an equivalent water-based product.
- It requires less maintenance over time.
- It takes longer to dry
- The product has a sharp odor that some people find objectionable
- It is more challenging to clean and requires the use of mineral spirits
Water-based polyurethane vs oil-based polyurethane side by side
Oil- and water-based polyurethanes are among the most durable topcoats for hardwood. Even though they exist in liquid form, they dry to form a rock-solid film on the wood surface, protecting it from moisture, chemicals, and physical damage.
While both products serve the same purpose, they have a few differences that may make one a preferable choice for a given application.
Here is a detailed comparison of water-based polyurethane vs oil-based polyurethane.
Oil-based polyurethane has traditionally been considered more durable than its water-based cousin. Initial water-based polyurethane formulations tended to last fewer years on surfaces, so you had to refinish the items sooner.
However, water-based polyurethanes have caught up with oil-based types thanks to improvements in their formulations. They now offer the same resistance to corrosion, marring, scuffing, UV, and water damage.
While water-based formulations still have a lower percentage of solids than oil-based products, they are no less durable. You simply need to apply more coats to achieve the desired level of protection when using a water-based product.
Verdict: the difference in durability is indiscernible, so it’s a tie.
Color and tint
Polyurethanes are generally clear-colored. However, oil-based formulations tend to have an amber tint that gets yellower over time.
In contrast, water-based poly is clear and remains that way over time if the product is well-engineered. As such, a water-based sealant is an ideal choice if you want to preserve your wood’s natural color and character.
But if you prefer the glow of an amber or golden tint, an oil-based product is more suitable for you. Notice that tinted polyurethane will continue yellowing over time, meaning the color intensity becomes more noticeable.
If you are sealing stained wood, this difference in the sealant color may be negligible due to the effect of the wood stain beneath it. So you may want to keep these variables in mind when deciding which way to go with your polyurethane choice.
Note: Your water-based polyurethane will appear milky in the container but becomes crystal clear after application. So do not let this milky color inside the container bother you or influence your decision.
Verdict: Oil-based poly has a tint, while water-based poly is clear
Drying and recoating times
Since oil-based polyurethane has a thicker consistency than water-based poly, it takes more time to dry. You can apply only one coat of oil-based poly to your hardwood floor in 24 hours due to its long recoat times.
Since each project requires two to three coats, you must plan with at least three days plus cure time.
On the other hand, a water-based product dries pretty fast. The product has shorter recoat times, allowing you to apply up to four coats on the same day in warm weather.
Suppose you seal a hardwood floor with waterborne polyurethane; you should be able to walk on it with socks in approximately four to six hours under ideal temperature and humidity conditions.
In contrast, a hardwood floor with oil-based poly will require at least 24 hours of drying time before you can walk on it with socks.
Verdict: Water-based finishes win the round
Odor and safety
Oil-based polyurethane consists of solvents in its formula. These highly flammable solvents produce noxious fumes that can be harmful to inhale.
The volatile organic compounds (VOCs) from oil-based products also have a strong odor. This quality makes oil-based poly unideal for people with allergic reactions to such scents.
Therefore, you must usually wear a respirator mask when working with solvent-based polyurethane to protect you from the noxious fumes and their strong odor.
Also, you must handle rags and tools used to apply solvent-based poly carefully, keeping them away from sources of combustion. This measure is crucial to prevent the risk of fire associated with such solvent-based products.
In contrast, water-based poly does not have any perceptible odor, making it safe for people with smell allergies.
They are also easier to handle and clean off tools with soap and water. The water base also gives this type of polyurethane a low VOC profile—up to 50 percent lower volatile organic compounds than oil-based poly.
This characteristic means it is safe to apply a water-based product without wearing a respirator mask.
Verdict: Waterborne poly wins
Number of coats required
Since water-based polyurethanes typically contain fewer solids than their oil-based cousins, you must apply more coats to achieve the desired level of protection.
Most water-based formulas comprise only 30 to 35 percent solids. Equivalent oil-based polyurethane formulas usually have 45 to 50 percent solids, making them thicker and heavier.
While both product formulations are equally durable, you must apply more coats of water-based poly to achieve optimum surface protection.
Ideally, you must apply four coats of a water-based poly compared to two or three coats of an oil-based product.
Verdict: Oil-based poly wins
Number of coats you can apply
Aside from the number of coats needed, you must also consider the number of layers available. This upper limit depends on how the product reacts to the substrate.
Waterborne poly reacts well to the substrate, allowing you to apply as many coats as you wish without a problem. In other words, you can apply up to six or an unlimited number of coats when using water-based poly.
However, the same rule does not apply to oil-based products. Oil-based polyurethane limits the number of coats you can apply. The product tends to form layers that might be prone to chipping after the first three or more layers.
Verdict: water-based poly is better in this regard
Thickness and flexibility
Polyurethane is generally accepted as the toughest sealant for hardwood floors and other projects.
However, the hardness levels differ between water- and oil-based polyurethanes, even though the line has become much thinner with improvements in water-based formulations.
Oil-based polyurethane has a thicker consistency than water-based poly. It also remains significantly flexible when dry.
On the other hand, water-based poly is thinner and more rigid when dry. This quality makes water-based poly more susceptible to surface scratching when dry.
However, the flexibility of solvent-based products also means they can experience dents more easily than water-based products.
Verdict: Oil-based poly is thicker and more flexible
Adhesion and compatibility with substrates
Both water- and oil-based polyurethanes are highly versatile. They bond to nearly any material, including metal, wood, concrete, carbon fiber, and fiberglass.
These two finishes have only one difference with regard to adhesion and substrate compatibility.
Waterborne polyurethane will seamlessly bond to a layer of water-based poly without any problems. However, you must sand between layers of solvent-based polyurethane to achieve proper adhesion.
Applying a fresh coat of oil-based poly over another layer of oil-based poly without sanding can result in adhesion problems.
Verdict: Water-based poly is the winner
Water-based polyurethane is a far more expensive product. It costs roughly twice as much as an equivalent volume of an oil-based poly.
If a water-based polyurethane costs less than roughly twice that of an equivalent oil-based product, it might be a cheap brand that will likely not last as required.
Expect to pay around $350.00 for the same amount and brand of water-based polyurethane, which costs approximately $150.00 in the oil-based formulation.
Verdict: Oil-based poly is more affordable
Ease of application
Both polyurethane formulations are available in spray versions and cans that you can brush onto the wood.
Spay bottles make the application easier and quicker, especially for beginners. However, this option may be expensive for a larger project, so you may opt for a brush-on option instead.
Most brands also offer self-leveling products in both water-based and oil-based polyurethane formulations. This makes it easier to apply the product with a paintbrush without worrying about brush marks.
Verdict: it is a tie.
When to use water-based vs. oil-based polyurethane
Both water- and oil-based polyurethane dry to form a durable protective coat over the substrate. But their differences can make one more suitable and preferable than the other for specific applications.
When to use water-based polyurethane
- Consider using a water-based product if you have any smell sensitivities.
Oil-based polyurethane is loaded with volatile organic compounds that produce a pungent odor. Persons with allergies or sensitivities to such sharp smells may find this product objectionable.
In contrast, water-based polyurethane has almost no smell at all, making it safe for users with smell sensitivities.
- Water-based polyurethane is also ideal if you want to preserve your wood’s natural color and texture.
The sealant is completely clear-colored, so it will not alter the color of your wood.
Oil-based polyurethane has a golden tint that only gets darker with time. So it will give your hardwood floors an amber tone that may not be ideal if you prefer the wood’s natural appearance.
- Use water-based poly when working on very light-colored wood species like maple.
These wood types look best with a water-based sealant because it does not alter or taint their color and character.
The clear polyurethane formula allows the beautiful light color of maple and such like woods to show through the finish.
When to use oil-based polyurethane
- Use oil-based poly when working on naturally yellowish wood types like Pine, Ash, and Fir.
The golden tint of the sealant only amplifies the wood’s character, making it pop. Since the wood is naturally golden, the coat of polyurethane makes it glossy and more beautiful by bringing out the yellow tones.
- Go for oil-based poly if you have several days to spend on the project.
Solvent-based polyurethane takes much longer to dry, at least 24 hours before you can recoat it. This means you need at least one day for each coat of oil-based polyurethane. Unlike a water-based poly project that you can finish within one day, oil-based poly may take up to a week.
If you are sealing a stained piece of wood or hardwood floor, you will also need to factor in the stain’s drying time. Here is an article on how long to let wood stain dry before polyurethane.
- Use oil-based poly where there is plenty of ventilation
Since the product is highly toxic and emits noxious fumes, you must use it in a well-ventilated area. This makes it ideal for use outdoors or in spacious rooms with adequate air circulation.
What to consider when choosing between oil and water-based poly
Consider the following factors when deciding between water-based polyurethane and oil-based polyurethane.
- Project timeline. You can apply up to four coats of water-based polyurethane within one day. This means you can complete sealing a hardwood floor with water-based polyurethane on the same day and use that room that night, making it ideal for time-sensitive projects like commercial spaces that must stay open as much as possible.
- Wood color. Oil-based poly leaves a golden hue on the substrate. This makes it ideal for naturally yellowish woods but not suitable for light-colored ones like maple. Reserve light-colored woods like maple for water-based polyurethane.
- Cost and labor fees. If you are completing the project yourself, the lower upfront cost of purchasing oil-based poly may appeal to you. However, labor costs may accumulate for an oil-based product if you’re hiring contractors for the project. The product’s longer dry times may require the contractor to travel back and forth to the job site, leading to higher total costs than a water-based finish.
- Customer preference. While some prefer the amber tone of oil-based polyurethane, others find it a deal breaker. So when deciding between water and oil-based polyurethane, think about your color preferences beforehand.
Which is better, water or oil-based polyurethane?
There is no outright winner between water-based and oil-based polyurethane. The better choice between the two depends on customer preferences and other determining factors, such as the wood type being finished.
What is the main disadvantage of using water-based polyurethane?
The main disadvantage of using water-based polyurethane is its expensive cost. The product is generally double the price of equivalent oil-based polyurethane. It also requires more coats to achieve the desired durability due to its relatively low number of solids.
Which lasts longer, oil-based polyurethane or water-based polyurethane?
Neither oil-based polyurethane nor water-based poly is more durable than the other. The two products perform the same in durability as long as they are of the right quality and the required number of coats is applied.
What is easier to apply, water-based or oil-based polyurethane?
Water-based polyurethane may be considered easier to apply because it dries quickly, allowing for more coats to be applied in less time than with solvent-based polyurethane.
Water-Based Polyurethane Vs Oil Based Polyurethane: Final Thoughts
The days when oil-based polyurethane offered better durability than water-based polyurethane are gone. Today’s polyurethane finishes boast the same durability ratings regardless of their formula—water or solvent-based.
Therefore, when deciding between water-based polyurethane and oil-based polyurethane, consider your color preference, VOC tolerance, budget, and application timeline to determine the most suitable type for your needs.
Ideally, choose a waterborne product when you have little time to complete the project, prefer a clear color, and have little VOC tolerance.
Otherwise, choose oil-based polyurethane if you prefer some golden tint on your wood, have a smaller budget, and do not mind spending more time on the project.