Polyurethane vs Varnish – Which is the Superior Wood Finish?

When it comes to woodworking, your finish can make or break your project. The right finish not only enhances the beauty of the wood but also protects it from damage. Two popular choices among woodworkers are polyurethane and Varnish. But which one is superior? Let’s dive in and find out.

Understanding Polyurethane

Polyurethane, often referred to as the “armor” of wood finishes, is a type of synthetic finish known for its durability. It’s a plastic resin that forms a hard, protective layer over the wood, making it resistant to water, heat, and other forms of damage.

This finish is commonly used in high-traffic areas like kitchen tables and hardwood floors, where the wood is likely to take a beating. It’s also a favorite for outdoor furniture, as it can withstand the elements without peeling or cracking.

Polyurethane comes in various sheens, from matte to high gloss, allowing you to choose the level of shine that suits your project. It’s also available in oil-based and water-based forms. The oil-based polyurethane offers the wood a warm, amber tone, while the water-based version is clear, making it ideal for light-colored woods.

Understanding Varnish

Varnish, on the other hand, is a traditional wood finish that has been used for centuries. It’s a blend of oil and resin that penetrates the wood to protect it from within, rather than forming a hard shell on the surface like polyurethane.

This finish is known for its flexibility, which allows it to expand and contract with the wood without cracking. This makes Varnish an excellent choice for interior and exterior finishes, as it can withstand changes in temperature and humidity.

Varnish is available in a range of sheens, from flat to high gloss, and it can be tinted to enhance the natural color of the wood. It’s also known for its long-lasting shine, which can add a touch of elegance to any woodworking project.

However, Varnish does require more maintenance than polyurethane. It must be reapplied every few years to maintain its protective qualities and shine. But for many woodworkers, this extra effort is worth it for Varnish’s natural, hand-rubbed look.

Comparison of Polyurethane and Varnish

When comparing polyurethane and Varnish, it’s like comparing apples and oranges – they’re both fruits but offer different flavors. Similarly, polyurethane and Varnish serve the same purpose – to protect and beautify wood – but they do so differently.

Polyurethane, a plastic resin, forms a hard, protective shell over the wood. It’s highly resistant to water, heat, and scratches, making it an excellent choice for high-traffic areas and outdoor furniture. It’s available in oil- and water-based forms, with the former offering a warm, amber tone and the latter providing a clear finish.

Varnish, on the other hand, penetrates the wood, protecting it from within. It’s flexible, allowing it to expand and contract with the wood without cracking. This makes it suitable for both interior and exterior finishes. However, Varnish requires more maintenance than polyurethane, needing to be reapplied every few years.

Polyurethane vs Varnish: Which is Stronger?

The question of strength and durability between polyurethane and Varnish can be tricky. Polyurethane takes the lead when discussing resistance to physical damage like scratches and impacts. Its hard, plastic-like coating is incredibly tough, making it a favorite for surfaces with many use or wear, like floors or kitchen tables.

For instance, imagine a bustling restaurant with wooden tables. These tables see a lot of action – hot plates, spilled drinks, cutlery scratches – you name it. A polyurethane finish on these tables would resist this daily wear and tear, keeping the wood underneath safe and sound.

While not as hard as polyurethane, Varnish excels in its flexibility and ability to withstand environmental changes. It’s less likely to crack or peel in fluctuating temperatures and humidity. So, a varnish finish would be more durable for a wooden deck exposed to the elements – sun, rain, cold, and heat.

Application Process of Polyurethane and Varnish

Applying a finish to your wood project is a crucial step that can significantly impact the final result. Here’s a step-by-step guide on how to apply both polyurethane and Varnish.

How to Apply Polyurethane

  1. Preparation: Start by sanding the wood surface to make it smooth. Wipe away any dust with a damp cloth.
  2. Application: Using a high-quality brush, apply a thin coat of polyurethane following the grain of the wood.
  3. Drying: Allow the first coat to dry completely. Depending on the specific product and environmental conditions, this can take anywhere from a few hours to overnight.
  4. Sanding: Once dry, lightly sand the surface with fine-grit sandpaper to remove any bumps or bubbles. Wipe away the dust.
  5. Repeat: Apply a second coat of polyurethane, let it dry, and then sand again. Repeat this process until you’ve applied at least three coats.

How to Apply Varnish

  1. Preparation: Like with polyurethane, start by sanding the wood and wiping away the dust.
  2. Application: Apply a thin coat of Varnish using a high-quality brush, following the grain of the wood.
  3. Drying: Allow the Varnish to dry completely. This can take longer than polyurethane, sometimes up to 24 hours.
  4. Sanding: Sand the surface lightly with fine-grit sandpaper, then wipe away the dust.
  5. Repeat: Apply additional coats of Varnish, allowing each to dry and sanding in between. Three to four coats are typically recommended.

Polyurethane and Varnish for Different Wood Types

When it comes to choosing between polyurethane and Varnish for different types of wood, it largely depends on the use of the item.

For hardwood floors, polyurethane is often the go-to choice. Its hard, durable finish can withstand the heavy foot traffic that floors typically see. Plus, it’s resistant to water and other spills common in homes.

For outdoor decks, Varnish can be a better option. Its flexibility allows it to withstand the changing weather conditions exposed to outdoor wood. However, remember that it must be reapplied more frequently than polyurethane.

When it comes to furniture, both finishes can work well. It depends on the look you’re going for and how much wear and tear the furniture will see. For a natural, hand-rubbed look, Varnish is a great choice. For a high-gloss, durable finish, consider polyurethane.

Cost Comparison: Polyurethane vs Varnish

Regarding cost, both polyurethane and varnish can vary significantly based on the brand, quality, and type (oil-based or water-based). On average, you can expect to pay anywhere from $10 to $20 per quart for both finishes.

However, the total cost of your project will also depend on the size of the area you’re finishing and the number of coats you apply. Polyurethane, a thicker finish, often requires fewer coats than Varnish, making it more cost-effective for larger projects.

Remember that the cost of application tools, such as brushes and sandpaper, will also factor into your total cost. High-quality brushes, which can provide a smoother finish, will cost more but can be a worthwhile investment.

Health and Safety Considerations

Both polyurethane and Varnish contain chemicals that can be harmful if inhaled or ingested, so it’s essential to take precautions when using these finishes.

Always work in a well-ventilated area to minimize inhalation of fumes. Consider wearing a respirator if working in a small or enclosed space.

Wear protective clothing, including gloves and long sleeves, to prevent skin contact. If you get any finish on your skin, wash it off immediately with soap and water.

Never eat or drink while working with these finishes, and always wash your hands thoroughly before eating or touching your face.

If you’re working with oil-based polyurethane or Varnish, be aware that the rags used for application or cleanup can spontaneously combust if not disposed of properly. Always soak used rags in water and store them in a sealed, water-filled metal container before disposing.

Common Misconceptions about Polyurethane and Varnish

When it comes to wood finishes, a few misconceptions often float around. Let’s debunk some of these myths.

Varnish and Polyurethane are the Same Things

While Varnish and polyurethane serve the same purpose – to protect and beautify wood – they are not the same. Polyurethane is a synthetic finish that forms a hard, protective shell over the wood. Conversely, Varnish is a blend of oil and resin penetrating the wood to protect it from within.

More Coats Means More Protection?

While it’s true that a certain number of coats are necessary for adequate protection, more is not always better. Too many coats of polyurethane can make the finish look plastic-like, while too many coats of Varnish can make the finish cloudy. It’s best to follow the manufacturer’s instructions for the number of coats.

Polyurethane vs Other Finishes

Polyurethane is just one of many finishes available for wood. Let’s see how it stacks up against other popular finishes like shellac and lacquer.

Polyurethane vs Shellac

Shellac is a natural finish derived from the lac bug’s secretions. It’s known for its beautiful, warm glow and ability to bring out the wood’s natural grain. However, shellac is not as durable as polyurethane and is susceptible to damage from water and alcohol. It’s best used for decorative pieces that won’t require wear and tear.

Polyurethane vs Lacquer

Lacquer is a fast-drying finish that’s often used on furniture and cabinets. It’s more durable than shellac but not as durable as polyurethane. Lacquer can be sprayed on, making it easier to apply than polyurethane, but it requires a well-ventilated area due to its strong fumes.

Varnish vs Other Finishes

Just like polyurethane, Varnish also has its counterparts in the world of wood finishes. Let’s see how it compares to shellac and lacquer.

Varnish vs Shellac

While both Varnish and shellac can give a warm, rich finish to wood, they differ in durability and application. Being less durable, Shellac is often used for projects that won’t be exposed to heavy wear or moisture. Varnish, with its superior durability and resistance to water, is more suited for outdoor furniture and high-traffic areas.

Varnish vs Lacquer

Lacquer, known for its fast-drying and high-gloss characteristics, is often used on furniture and cabinets. However, it doesn’t have the same resistance to heat and chemicals as Varnish. While lacquer can provide a beautiful finish, Varnish wins in durability and protection.

Expert Opinions

Industry experts often have varied opinions regarding choosing between polyurethane and Varnish. Some experts lean towards polyurethane for its superior durability and resistance to water and heat, making it an excellent choice for floors and outdoor furniture.

Others prefer Varnish for its flexibility and traditional, hand-rubbed look. They argue that while Varnish may require more maintenance, the natural look and feel it gives to wood are worth the extra effort.


There’s no one-size-fits-all answer in the great debate of polyurethane vs Varnish. Both finishes have their strengths and weaknesses, and the best choice depends on the specific needs of your project.

Polyurethane, with its hard, protective shell, offers superior durability, making it an excellent choice for high-traffic areas and outdoor furniture. With its flexibility and ability to penetrate the wood, Varnish provides a traditional, hand-rubbed look that many woodworkers love.