Polyurethane Water-Based vs Oil-Based: Choosing the Right Finish

Wood finishes there to protect wood from various elements, so it does not become dry and lifeless. Coating wood cabinetry or furniture gives it richness and depth, protecting it from knocks, scrapes, and the weather. Oil-based and water-based polyurethanes are different finishes for different needs. It does not matter if you are finishing floors, trim, doors, or any wood product, once you spot the difference between the two, choosing between water-based and oil-based polyurethane will be easier. This article will shed more light on what each polyurethane can do better than the other.

What is Polyurethane?

It is a tough varnish formulated so that its resin molecules bond tightly with one another as it dries. As a result, the finish becomes more resistant to water, solvents, abrasion, and impacts. Some polys have oils that give wood a warm, amber tone whereas a water-based poly keeps its light color. 

Water-Based Polyurethane

Advantages of water-based polyurethane

• Eco Friendly
• Faster dry time
• Durability
• Clear finish 
• Non-irritant odor

Disadvantages of water-based polyurethane

• Less affordable 
• Requires more coats

Oil-Based Polyurethane: Pros and Cons

Advantages of oil-based polyurethane

• More affordable 
• Durable
• Few coats
• Excellent abrasion 
• Scratch resistance

Disadvantages of oil-based polyurethane

• Sharp odor
• Dries slowly

Durability and Longevity

Water-based polyurethane tends to be less durable than oil-based products as it scratches and dents easily. Oil-based polyurethane coatings provide excellent abrasion and scratch resistance. That makes it ideal for wood floors or any application, such as cabinets, railings, or countertops where durability is a requirement.

Appearance and Finish

Water-based polyurethane appears milky-white in the can but is clear when dry. Less to no color is imparted by the water-based polyurethane. It is not yellow. A single coat of oil-based polyurethane is thick enough, whereas water-based polyurethane requires multiple coats for the final look. It is hardly possible to apply five to eight coats of water-based polyurethane. Oil-based polyurethane coatings give a rich, golden glow in a few coats. It is available both in spray and brush-on formats. As a result, you get a hard protective shell in fewer coatings. Unlike water polyurethane, it leaves a slightly yellow sheen due to multiple coatings.

Application Process

A step-by-step guide to applying water-based polyurethane

1. Start by sanding your project. 
2. Apply a thin coat of polyurethane with a fine brush, foam pad, or cloth.
3. Let the first coat dry, sand it lightly with a fine-grit sandpaper, and apply a second coat. 
4. Work along the grain and avoid excess polyurethane.

Step-by-step guide to applying oil-based polyurethane

1. Prep the wood finish for polyurethane by sanding for a smooth surface.
2. Remove dust and dirt.
3. Set up a workspace.
4. Stir before use.
5. Apply the first coat in long strokes, into the direction of the grain of the wood.
6. Allow the polyurethane to dry for several hours until dry.
7. Apply a second coat of polyurethane.
8. Allow the polyurethane to cure before handling. Let it dry for at least 24 hours before handling, give it 2 or 3 days to cure.

Drying Time and Curing

For a faster-drying wood floor finish, use water-based polyurethane. Water-based polyurethane can take from 3 to 21 days to cure. It takes six hours to dry. An oil-based Polyurethane takes 24 hours to dry. Oil-based polyurethanes can be cured after 30 days.

Odor and VOC Emissions

Water-based poly has low VOC content, while oil poly has a high concentration of those. 

Compatibility with Different Surfaces

Which surfaces work best with water-based polyurethane?

• Hardwood Floors
• Paper
• Cardboard
• Plastics

Which surfaces work best with oil-based polyurethane?

• Hardwood floors
• Cabinets
• Furniture 
• Woodwork

Maintenance and Recoating

How to maintain and recoat water-based polyurethane finishes

Dirt, oil, and grime build up over time and are removed by regular dust mopping or vacuuming. An occasional thorough cleaning using a damp mop is needed. Do not allow water to stand on the floor. The quick dry coat allows the surface to dry in 2 hours. 

How to maintain and recoat oil-based polyurethane finishes

An oil-based Polyurethane takes 24 hours before being ready for sanding or touching. Regular dust mopping and damp mopping are required. Do not wet mop. Use only steam mops, or damp mopping using distilled white vinegar or glass cleaner heavily diluted with water to clean your flooring.

Resistance to Wear and Tear

Water-based polyurethane scratches and dents easily, whereas Oil-based polyurethane coatings provide excellent abrasion and scratch resistance, making them a great choice for wood floors or for any application such as cabinets, railings, or countertops where durability is critical.

Environmental Considerations

Water-based polyurethane is more environmentally friendly since it is easy to apply and dries quickly. However, it may not be as durable as oil-based polyurethane. Oil-based polyurethane is highly durable, with a glossy fit, and nish but has a longer drying time. It may emit higher VOC levels.

Cost Analysis

Water-based polyurethane can cost 2-3x that of oil-based. However, oil-based polyurethane has the additional dry time, requiring repeat visits. Water-based polyurethane is less affordable than oil. The raw materials used to make water-based polyurethane cost more than oil-based polyurethane, making the final price a bit higher. 

DIY vs. Professional Application

Water-based poly is better applied by a professional. Oil-based polyurethane is self-leveling, making it easier to achieve a smooth, professional finish, free from brush marks. 

Project Suitability

Water-based polyurethane is more versatile than oil-based polyurethane. It forms strong bonds with multiple materials such as wood, non-ferrous metal, fiberglass, stone, cement, and carbon fiber. Oil-based polyurethane also adheres well to various surfaces, except for its layers.

Trends and Innovations

Rigid polyurethane foams are introduced in highly energy-efficient and flexible insulations. These foams reduce energy costs in residential and commercial properties. Modifications in the raw material have produced a polyurethane suitable for every application.

Real-Life Case Studies

A porch swing has been coated using a water-based polyurethane (Emtech EM9300 Polycarbonate Urethane) (Targetcoatings.com). Water-based polyurethane will allow for a fast recoat time, low odor / non-flammable environment, offering great UV and water resistance. 

You can also use an oil-based stain and clear coat it with a water-based polyurethane. Allow the oil-based stain to dry for 12-18 hours, then lightly wipe the stain surface with a solution of water and denatured alcohol mixed 1:1, before applying the water-based polyurethane.

Choosing the Right Polyurethane for You

• Drying time
• Durability 
• Odor
• Compatibility

Summary: Making an Informed Choice

In summary, both water-based and oil-based polyurethane give better results, but the choice depends on your budget, desired finish, availability and type of surface. Water-based polyurethanes are better for dealing with messy, odorous solvents. They are easy to apply and easy to clean. For a thinner and more flexible coating, water-based polyurethanes are ideal. Oil-based polyurethane provides a hard appearance. Not many coats are required. Use it when good ventilation is possible or when the home is unoccupied during curing. To make an informed decision, you should take the time to read this article.

FAQs

   1. Are water-based polyurethane finishes as durable as oil-based?

Water-based polyurethane coatings have improved considerably and now offer durability comparable to that of oil-based products. Traditionally, oil-based polyurethanes were more durable, but recent advances in water-based polyurethane technology have narrowed this gap.

Water-based polyurethanes dry faster, give off less odor and are easier to clean (with soap and water) than oil-based products. They retain a clear finish, whereas oil-based versions can yellow over time.

The choice between water-based and oil-based polyurethane depends on the requirements of the project. For high-traffic or high-traffic areas such as floors in public buildings, oil-based polyurethane is the better choice due to its longer durability. For indoor furniture or projects where quick drying and low odor are important, water-based polyurethane is preferable.

   2. Do water-based finishes cost more than oil-based ones?

Water-based polyurethane coatings are generally more expensive than oil-based coatings. This cost difference is due to the more advanced manufacturing technology required for waterborne coatings and the benefits they offer. Water-based paints have less odor, dry faster, are easier to clean (with soap and water), are less flammable and emit fewer volatile organic compounds (VOCs), making them more environmentally friendly and safer for interiors.

Oil-based finishes, on the other hand, are less expensive, give the wood a traditional amber sheen, are more durable in high-traffic areas and have a longer working time, which is an advantage in application.

The price difference varies depending on brand, quality and product features. When considering the total cost of a project, factors such as the number of coats, deck area and additional tools or materials should be considered. In some cases, the benefits of water-based paints justify their higher initial cost.

   3. Is one type of polyurethane easier to apply for DIY projects?

Yes, for DIY projects, water-based polyurethane is generally considered easier to work with than oil-based polyurethane. Water-based polyurethane has less odor, dries faster and can be cleaned with soap and water, which is especially convenient for DIYers. It’s also less toxic and more environmentally friendly. However, it should be noted that oil-based polyurethane tends to be more durable and resistant to heat and solvents, making it a better choice for some projects. When choosing a polyurethane, you should consider the specific requirements of your project, including the desired finish, durability and your experience with such materials.

   4. Can water-based and oil-based polyurethane be used interchangeably?

Water-based and oil-based polyurethanes, while both used as protective finishes, have distinct properties that make them suitable for different applications and not interchangeable.

Drying Time: Water-based polyurethane dries faster, offering a quick turnaround but shorter working time.

Appearance: Oil-based polyurethane adds a warm, amber tint to wood, enhancing wood grains. Water-based polyurethane dries clear, preserving the wood’s natural color.

Odor and VOCs: Water-based polyurethanes emit lower volatile organic compounds (VOCs) and have less odor, making them preferable for indoor use, especially in areas with poor ventilation.

Durability: Oil-based polyurethane is more durable, suitable for high-traffic areas and surfaces exposed to heat and chemicals, like floors and kitchen counters.

Application: Applying water-based polyurethane over oil-based can lead to adhesion issues. Conversely, oil-based polyurethane can be applied over cured water-based polyurethane.

Environmental Considerations: Water-based polyurethanes are more eco-friendly with lower VOCs and simple soap-and-water cleanup. Oil-based varieties require mineral spirits for cleanup and have higher VOC levels.

5. Which type of polyurethane is better for the environment?

Water-based polyurethane is more environmentally friendly than oil-based polyurethane for several reasons:

• Lower VOCs: Water-based polyurethanes have fewer volatile organic compounds, reducing air pollution and health risks.
• Reduced Odor: They emit less odor, enhancing indoor safety and comfort.
• Easier Cleanup: Cleanup involves soap and water, avoiding the environmental impact of chemical solvents.
• Faster Drying Time: They dry quicker, saving time and energy.
• Less Resource-Intensive: Oil-based polyurethanes rely on petrochemicals, which have a larger environmental footprint.

However, water-based polyurethanes might not be the best choice for all situations. Oil-based polyurethanes offer greater durability and resistance to heat and solvents, preferable in high-traffic or industrial settings.