Why Use Foam Brushes for Polyurethane?

Have you ever found yourself standing in the paintbrush aisle, utterly perplexed by the variety of available brushes? If you plan to apply polyurethane, one of the most common dilemmas is whether to use a foam brush. Let’s dive into the world of foam brushes and understand their role in applying polyurethane.

As the name suggests, foam brushes have a foam head instead of bristles. They are often used for applying paints, stains, and finishes, including polyurethane. The foam head allows for a smooth, even application, making it a popular choice for many DIY enthusiasts and professionals.

But why exactly are foam brushes preferred for polyurethane? It’s all about the finish. Polyurethane is a type of finish that protects and enhances the natural beauty of wood. Foam brushes’ smooth, absorbent nature allows for a consistent, streak-free finish, which you need when working with polyurethane.

Types of Brushes for Polyurethane and Their Comparison

When it comes to applying polyurethane, there are several types of brushes you can choose from. Each has its own set of advantages and disadvantages. Let’s compare foam brushes with natural bristle, synthetic, and chip brushes.

Foam Brushes

Foam brushes are a favorite for many due to their affordability and ease of use. They are excellent for achieving a smooth, even finish without visible brush strokes. However, they may not be as durable as other types of brushes. They can disintegrate with prolonged use or when used with harsh solvents.

Natural Bristle Brushes

Natural bristle brushes are made from animal hair and are known for holding a large amount of finish. They are excellent for oil-based polyurethane but not suitable for water-based polyurethane, as the bristles can absorb water and become limp.

Synthetic Brushes

Synthetic brushes, made from nylon or polyester, are versatile and can be used with oil- and water-based polyurethane. They are durable and maintain their shape well, but they may leave visible brush strokes if not used properly.

Chip Brushes

Chip brushes are inexpensive brushes that are often used for one-time use. They can leave a good finish, but the bristles tend to fall out during application.

Using Foam Brushes for Different Types of Polyurethane

When it comes to applying polyurethane, the process can vary slightly depending on whether you’re using water-based or oil-based polyurethane. Here’s a step-by-step guide on how to use foam brushes for each type.

Water-Based Polyurethane

Water-based polyurethane is known for its low odor and quick drying time. Here’s how you can apply it using a foam brush:

  1. Preparation: Start by preparing the surface. It should be clean, dry, and lightly sanded. Remove any dust with a tack cloth.
  2. Application: Dip the foam brush into the polyurethane, ensuring it’s not overly saturated. Apply the polyurethane in long, even strokes along the wood grain.
  3. Drying: Allow the first coat to dry. Water-based polyurethane dries faster than its oil-based counterpart, which may take a few hours.
  4. Sanding: Once dry, lightly sand the surface with fine-grit sandpaper. This helps the next coat adhere better.
  5. Repeat: Wipe away dust with a tack cloth and apply the next coat. Repeat this process until you’ve applied the desired number of coats.

Oil-Based Polyurethane

Oil-based polyurethane provides a durable finish and enhances the natural color of the wood. Here’s how to apply it with a foam brush:

  1. Preparation: As with water-based polyurethane, the surface should be clean, dry, and lightly sanded.
  2. Application: Dip your foam brush into the polyurethane. Apply it in long, even strokes, working along the wood grain.
  3. Drying: Allow the coat to dry. This can take longer than water-based polyurethane, often up to 24 hours.
  4. Sanding: Once dry, sand the surface lightly with fine-grit sandpaper.
  5. Repeat: Remove dust with a tack cloth and apply the next coat. Continue this process until you’ve achieved the desired finish.

Can You Reuse Foam Brushes After Polyurethane?

When reusing foam brushes after applying polyurethane, the answer is a resounding “maybe.” It largely depends on the type of polyurethane you’ve used and how well you clean and care for your brush after use.

Foam brushes used with water-based polyurethane can often be cleaned and reused. Rinse the brush thoroughly in warm water until the water runs clear. Then, gently squeeze out any excess water and let the brush air dry.

On the other hand, if you’ve used oil-based polyurethane, cleaning becomes a bit more challenging. Oil-based finishes require a cleanup solvent, such as mineral spirits or paint thinner. To clean your foam brush, swish it in a container of the appropriate solvent, then rinse it in warm soapy water. Squeeze out the excess and let it air dry. However, be aware that harsh solvents can sometimes cause the foam to break down over time.

It’s worth noting that while it’s possible to clean and reuse foam brushes, they are often considered disposable due to their low cost. If you notice the foam starting to disintegrate or if it’s not as absorbent as it once was, it’s best to replace it. After all, your brush’s quality can significantly impact your finish’s quality.

Applying Varnish with Foam Brushes

Varnish is another popular finish used to protect and enhance wood. Like polyurethane, it can be applied with a foam brush for a smooth, even finish. Here’s a step-by-step guide on how to do it:

  1. Preparation: Start by preparing your wood surface. It should be clean, dry, and sanded smooth. Any dust or debris should be removed with a tack cloth.
  2. Stir the Varnish: Unlike paint, varnish should not be shaken as this can introduce bubbles. Instead, stir it gently to ensure it’s well mixed.
  3. Load the Brush: Dip your foam brush into the varnish. It’s important not to overload the brush; it should be wet but not dripping.
  4. Apply the Varnish: Using the loaded foam brush, apply the varnish in long, even strokes along the wood grain. The goal is to apply a thin, even coat.
  5. Let it Dry: Allow the varnish to dry completely. Depending on the varnish and conditions, this can take several hours or even overnight.
  6. Sand Between Coats: Lightly sand the surface with fine-grit sandpaper once the first coat is dry. This helps the next coat adhere better.
  7. Repeat: Wipe away any dust with a tack cloth and apply the next coat of varnish. Repeat this process until you’ve achieved the desired level of protection and shine.

Brush Cleaners for Polyurethane

Cleaning brushes after applying polyurethane is essential in maintaining your tools’ longevity and effectiveness. The type of cleaner you’ll need depends largely on the polyurethane you’ve used.

Water-Based Polyurethane

If you’ve used water-based polyurethane, cleaning your brushes is a breeze. Warm, soapy water is usually all you need. Rinse the brush under running water, working the soap through the bristles or foam to remove the polyurethane. Rinse thoroughly until the water runs clear, then squeeze out any excess water and allow the brush to air dry.

Oil-Based Polyurethane

You’ll need a solvent such as mineral spirits or paint thinner for brushes used with oil-based polyurethane. Here’s how to clean your brushes:

  1. Wipe Off Excess: Remove any excess polyurethane from the brush onto a rag or paper towel.
  2. Soak in Solvent: Pour a small amount of solvent into a container and soak the brush for a few minutes. This will help loosen the polyurethane.
  3. Work the Solvent Through: Using your fingers or a brush comb, work the solvent through the bristles or foam.
  4. Rinse and Repeat: Rinse the brush in a container of clean solvent. Repeat the process until the solvent stays clear.
  5. Wash and Dry: After the solvent rinse, wash the brush in warm, soapy water, rinse, and allow it to air dry.

Remember, when working with solvents, it’s important to work in a well-ventilated area and use gloves to protect your skin. Also, dispose of used solvents properly, as they can be hazardous to the environment.

Best Brush Brands for Polyurethane

When it comes to applying polyurethane, the quality of your brush can make a significant difference in the final result. Here’s a look at some of the top brush brands well-suited for applying polyurethane.


Purdy is a well-respected brand in the painting industry, known for its high-quality brushes. Their brushes are handcrafted and designed to provide a smooth, even finish. For polyurethane application, the Purdy Ox-Hair series is a great choice. These brushes are made with natural ox hair and synthetic filaments, making them perfect for oil-based polyurethane. They are durable, easy to clean, and provide a smooth, even finish.


Wooster is another reputable brand that offers a wide range of brushes. Their Softip brush series is a popular choice for polyurethane application. These brushes feature soft, synthetic bristles that work well with water- and oil-based polyurethane. They are durable, easy to clean, and provide a smooth, even finish.


Pro-Grade offers a range of affordable, high-quality brushes. Their foam brush set is a great choice for polyurethane application. These brushes provide a smooth, even finish and are ideal for one-time use, eliminating the need for cleanup.

Jen Manufacturing

Jen Manufacturing is known for its foam brushes, which are ideal for applying smooth, even coats of polyurethane. These brushes are affordable and disposable, making them convenient for DIYers and professionals.

Safety Tips When Using Foam Brushes with Polyurethane

Working with polyurethane can be a rewarding experience, but it’s important to keep safety at the forefront. Here are some safety precautions to keep in mind when using foam brushes with polyurethane:

  1. Proper Ventilation: Polyurethane can release harmful fumes if inhaled in large amounts. Always work in a well-ventilated area to ensure these fumes can disperse.
  2. Use of Gloves: Polyurethane can be difficult to remove from skin. Wearing gloves can protect your skin and make cleanup easier.
  3. Eye Protection: To prevent accidental splashes from reaching your eyes, wearing safety glasses is a good idea.
  4. Proper Disposal: Dispose of used brushes and any leftover polyurethane under local regulations. Remember, polyurethane is flammable and should not be left in open containers.

Common Mistakes and Practical Tips When Using Foam Brushes

Even experienced DIYers can make mistakes when using foam brushes for polyurethane. Here are some common errors and practical tips to avoid them:

  1. Overloading the Brush: Dipping the brush too deeply into the polyurethane can lead to drips and an uneven finish. Dip only the brush tip and wipe off any excess on the side of the can.
  2. Rushing the Process: Applying polyurethane requires patience. Rushing can lead to visible brush strokes and an uneven finish. Take your time and apply thin, even coats.
  3. Skipping Sanding: Sanding between coats is crucial for a smooth, professional-looking finish. Don’t skip this step!
  4. Not Allowing Enough Drying Time: Each coat of polyurethane needs to dry fully before the next is applied. Not waiting long enough can lead to a sticky finish and longer overall drying time.
  5. Not Cleaning the Brush Properly: If you plan to reuse your foam brush, clean it thoroughly after each use. Leftover polyurethane can harden in the foam, rendering the brush useless.

Where to Buy the Best Foam Brushes for Polyurethane

Various online and physical stores make finding the right foam brush for your polyurethane project easier than ever. Here are a few places where you can find high-quality foam brushes:

  1. Amazon: This online marketplace offers various foam brushes from different brands. You can read customer reviews and compare prices to find the best option.
  2. Home Depot: This home improvement store carries a range of foam brushes suitable for polyurethane applications. You can shop online or visit a physical store.
  3. Lowe’s: Similar to Home Depot, Lowe’s offers a variety of foam brushes both online and in their physical stores.
  4. Local Hardware Stores: Don’t forget about your local hardware stores. They often carry a selection of foam brushes and can offer personalized advice.


Choosing the right brush for your polyurethane project can significantly affect the quality of your finish. Foam brushes are a popular choice with their smooth application and affordable price. However, using and cleaning them properly is important if you reuse them.

Remember, the key to a successful project is patience and preparation. Take your time, apply thin, even coats, and allow each coat to dry fully before applying the next. With these tips in mind, you’re on your way to achieving a flawless finish with your foam brush and polyurethane.