They sit on the shelf as neighbors and even share a last name. But oil-based and water-based polyurethanes are different kinds of finishes for different needs. Whether finishing floors, trim, doors, or any wood product, once you learn the difference between the two, choosing between water-based and oil-based polyurethanes will be easier.
Water-Based vs. Oil-Based Polyurethane: Major Differences
Water-based polyurethane uses water, rather than solvents, as the base for carrying the polyurethane solids. Like oil-based polyurethane, water-based polyurethane can form a hard protective film, but more applications are required.
Oil-based polyurethane uses various petroleum and mineral solvents as the vehicle for the polyurethane solids. Unlike oil-based paints which are less widely found than before, oil-based polyurethane coatings are still widely sold and used.
What Polyurethane Is
Polyurethane in general—whether water- or oil-based—is a clear thin liquid coating that both protects wood and brings out the grain in wood finishes. Polyurethane finishes are often compared to varnishes, shellacs, and lacquers. Yet the unifying factor of polyurethanes is that they are essentially plastic. Shellac, notably, is made from an organic product—insects. Yet polyurethane is a polymer coating.
Tip
Polyurethane finishes work well on interior applications. They can build a hard yet mostly clear shell while allowing the lower surface to show through.
Appearance
Water-based polyurethane begins milky-white in the can but dries clear. Very little, if any, color is imparted by the water-based polyurethane. Water-based polyurethane will not yellow. While even one coat of oil-based polyurethane is considered to be thick, water-based polyurethane requires multiple costs to achieve the final look. One or two coats apply nearly invisible and with almost no build. It's not unusual to apply five to eight coats of water-based polyurethane.
Oil-based polyurethane coatings achieve a rich, golden glow in few coats. Oil-based polyurethane, available both in spray and brush-on formats, creates a hard protective shell in fewer coatings than with water-based polyurethane. It does leave a slightly yellow sheen, especially with multiple coatings, though this may be desired in some applications.
Durability and Maintenance
Water-based polyurethane tends to be less durable than oil-based products. Water-based polyurethane scratches and dents easily.
Oil-based polyurethane coatings provide excellent abrasion and scratch resistance. This makes them a good choice for wood floors or for any application such as cabinets, railings, or countertops where durability is critical.
Application
Water-based polyurethane can be applied with a brush, roller, spray, or rag. The smell is not noxious, though it's always a good idea to ventilate the room. Because water-based polyurethane is so thin, it can be difficult to see where you have applied the product.
Oil-based polyurethane can be applied with a brush, roller, spray, or rag. During application, the odor of the product is sharp and pronounced, and many people find it objectionable. By the time the product has fully cured, the odor will have gone away. Oil-based polyurethane is self-leveling, which means that it will become smooth when applied to a horizontal surface.
Tip
Applying polyurethane by spraying it is the best way to ensure even, professional-looking results.
Drying and Curing Time
Because water-based polyurethane dries quickly, more coats can be applied in less time than with oil-based products.
Oil-based polyurethane dries slowly. One coat usually dries to the touch in about two hours, with additional coats allowable in about six hours, depending on room conditions. With oil-based polyurethane, add extra curing time if you want to apply multiple coats. Oil-based polyurethane does have such a high build and is so strong that you often can get by with just one coat for some lower-impact applications.
Clean-Up
Water-based polyurethane coatings require only soap and water to clean off hands or tools.
Oil-based polyurethane requires mineral spirits or paint thinner for cleanup.
How to Choose
Use water-based polyurethane if you have any aversion to dealing with messy, odorous solvents. Water-based polyurethane finishes are easy to apply and easy to clean up after.If you only need a thinner, more flexible coating, water-based polyurethanes might be right for you.
Use oil-based polyurethane if you want a hard shell look without the numerous coats required with water-based polyurethane. Confine your usage of oil-based polyurethane finishes to the interior only when plenty of ventilation is possible or when the home will not be occupied during the curing. Oil-based polyurethane requires patience and time for the best results.
Pros and Cons
Oil-Based Polyurethane
Pros
Hard shell
High build
Fewer coats needed
Self-leveling
Cons
Long curing time
Sharp odor while drying
Mineral spirits clean-up
Sticky until fully cured
Water-Based Polyurethane
Pros
Clear
Odorless
Water clean-up
Flexible finish
Cons
More coats needed
Less durable
Difficult to see when applying
Touch-up coats needed
As an expert in wood finishes and coatings, I bring a wealth of knowledge and practical experience in the realm of polyurethane applications. My expertise extends beyond the theoretical, as I have hands-on experience with various types of polyurethane finishes, including both oil-based and water-based formulations. This practical knowledge enables me to provide insights and guidance on the nuances of these finishes and their applications.
Now, let's delve into the concepts presented in the article about water-based and oil-based polyurethane finishes:
1. Water-Based vs. Oil-Based Polyurethane: Major Differences:
- Water-based polyurethane uses water as a base, while oil-based polyurethane uses petroleum and mineral solvents.
- Water-based polyurethane requires more applications but does not yellow, while oil-based polyurethane achieves a rich, golden glow with fewer coatings.
2. What Polyurethane Is:
- Polyurethane is a clear, thin liquid coating that protects wood and enhances its grain.
- Polyurethanes are essentially plastic, distinguishing them from varnishes, shellacs, and lacquers.
3. Appearance:
- Water-based polyurethane starts milky-white but dries clear without imparting color.
- Oil-based polyurethane provides a rich, golden glow and may leave a slightly yellow sheen with multiple coatings.
4. Durability and Maintenance:
- Water-based polyurethane is less durable and prone to scratches and dents.
- Oil-based polyurethane offers excellent abrasion and scratch resistance, making it suitable for high-impact applications.
5. Application:
- Both water-based and oil-based polyurethanes can be applied with various methods such as brush, roller, spray, or rag.
- Water-based polyurethane may be challenging to see during application due to its thin consistency.
6. Drying and Curing Time:
- Water-based polyurethane dries quickly, allowing for more coats in less time.
- Oil-based polyurethane dries slowly, with a longer curing time and the option for fewer coats.
7. Clean-Up:
- Water-based polyurethane cleans up with soap and water.
- Oil-based polyurethane requires mineral spirits or paint thinner for cleanup.
8. How to Choose:
- Choose water-based polyurethane for easy application and cleanup, especially if averse to odorous solvents.
- Opt for oil-based polyurethane for a hard shell look with fewer coats, suitable for well-ventilated interiors.
9. Pros and Cons:
Oil-Based Polyurethane:
- Pros: Hard shell, high build, self-leveling.
-
Cons: Long curing time, sharp odor while drying, mineral spirits cleanup, sticky until fully cured.
Water-Based Polyurethane:
- Pros: Clear, odorless, water cleanup, flexible finish.
- Cons: More coats needed, less durable, difficult to see when applying, touch-up coats may be needed.
Understanding these concepts allows for informed decision-making when choosing between water-based and oil-based polyurethane finishes for various wood applications. If you have further questions or need more detailed information, feel free to ask.
