Brushes can be a valuable investment for any DIYer or professional. When working with polyurethane, having the right brush is key to achieving the desired finish, but if they aren’t cared for properly, they can quickly become unusable, resulting in wasted money and time. That’s why it is important to know how to clean polyurethane brushes effectively.
In this blog post, I will guide you through the process of cleaning both oil-based and water-based polyurethane brushes. I will provide you with a list of materials you’ll need, step-by-step instructions, and tips to ensure that your brushes are properly cared for and can be reused for future projects.
How to clean polyurethane brushes – a quick overview:
- Water-based polyurethane is relatively easy to clean with hot water and soap. However, oil-based polyurethane is more challenging to remove and requires a solvent such as mineral spirits or paint thinner.
- After cleaning your brushes, make sure to dry them thoroughly and store them in a dry and cool place. This will help prevent any damage or deterioration to the brush bristles and ensure that they remain in excellent condition for future use.
Table of Contents
- General Questions
- What is polyurethane?
- What brush to use for polyurethane?
- Why should you clean polyurethane from the brush after use?
- How to store a brush between polyurethane coats?
- How to Clean Polyurethane Brush
- How to clean water-based polyurethane from your brush
- Method 1 – Clean with Hot Water
- Method 2 – Clean with Hot Water and Soap
- How to clean oil-based polyurethane from your brush
- Method 1 – Cleaning with Mineral Spirits
- Method 2 – Cleaning with Paint Thinner
- Method 3 – Cleaning with Vinegar
- How to clean water-based polyurethane from your brush
- Top Products to Clean a Polyurethane Brush
- How to clean dried polyurethane from your brush
What is polyurethane?
Polyurethane is a type of synthetic material that creates a protective and flexible coating for a variety of surfaces, including woodwork, flooring, and furniture. This material is highly resistant to wear and tear, making it a popular choice for both indoor and outdoor use.
There are two primary types of polyurethane: oil-based and water-based.
- Oil-based polyurethane is ideal for outdoor use due to its ability to resist water and UV rays. It dries slower than water-based polyurethane and gives off a strong odor, but creates a rich, amber-colored finish.
- Water-based polyurethane is ideal for indoor use due to its low odor and fast drying time. It dries clear and is suitable for lighter-colored woods.
Using polyurethane provides several benefits, including enhancing the natural beauty of the wood while providing a protective barrier against scratches, scuffs, and stains. It also offers UV protection, making it ideal for outdoor use
What brush to use for polyurethane?
When it comes to applying polyurethane, the type of brush you use can make a significant difference in the quality of the finish. There are two main types of polyurethane brushes: natural and synthetic.
Here is what you need to know:
- Natural brushes: Made from animal hair, such as bristles from hogs, oxen, or badgers. These brushes are more expensive than synthetic ones, but they are durable, hold more paint, and produce a smoother finish. They are also better suited for oil-based polyurethane because they hold up well to the solvents used in these products.
- Synthetic brushes: Made from nylon or polyester, these brushes are less expensive than natural ones and can be used for both water-based and oil-based polyurethane. They are less durable than natural brushes, but they are easy to clean and maintain their shape better. They are a good choice if you are on a budget or working with water-based products.
- Polyfoam brushes: These brushes are made from foam and are disposable. They are a good choice for small jobs or when you don’t want to clean up a brush afterward. Although they may not be recommended for polyurethane due to the possibility of leaving air bubbles and streaks in the finish, they are still one of my favorite choices.
Here’s a table summarizing the best brushes for oil-based and water-based polyurethane:
Average Price Range
Poor to Fair
Good to Excellent
Good to Excellent
Poor to Fair
Poor to Fair
Natural bristle brushes are typically more expensive, they may be a better option for oil-based polyurethane due to their ability to hold and spread the thicker product. On the other hand, synthetic bristle brushes are recommended for water-based polyurethane due to their ability to maintain their shape and provide a smooth finish.
NOTE: From my experience, using disposable foam brushes for small jobs or quick touch-ups can be convenient because there’s no need for cleanup. However, for larger projects, I recommend investing in a high-quality brush and taking the time to clean it properly after each use. This may take a bit more effort, but it will ensure that the brush lasts longer and gives a better finish.
On the other hand, if you don’t clean an expensive brush properly, you may end up having to throw it away, which is a waste of money. So, my advice is to choose the right brush for the job and take good care of it.
Why should you clean polyurethane from the brush after use?
Keeping your polyurethane brush clean after each use is an essential step to prolong its lifespan and ensure the quality of your projects. Neglecting to clean your brush can lead to hardened bristles, an uneven finish, and ultimately, a shorter lifespan for the brush.
Benefits of cleaning polyurethane from the brush after use:
- Polyurethane residue can dry and harden on the brush bristles, causing them to become stiff and ineffective.
- Not cleaning the brush immediately after use can interfere with the quality of the finish on your next project.
- Cleaning the brush after each use helps to maintain its quality, allowing you to reuse it for multiple projects.
- Failure to clean the brush can shorten its lifespan, as the bristles can become damaged and break off during the next use.
- Cleaning polyurethane from the brush after use is crucial to maintain its effectiveness and quality.
How to store a brush between polyurethane coats?
Proper storage of your polyurethane brush between coats is essential to maintain its quality and prolong its lifespan. If you plan to use the brush again within a few hours, you can keep it from drying out by sealing it in a plastic bag and storing it in a cool, dry area like a fridge. However, if you anticipate a longer gap between coats, it’s important to clean the brush thoroughly beforehand to prevent the polyurethane from hardening and causing damage to the bristles.
To clean the brush, use an appropriate cleaning agent based on whether you used oil-based or water-based polyurethane for the first coat. Once cleaned, make sure the brush is completely dry before storing it in a cool and dry environment, away from direct sunlight and humid conditions. Remember to avoid storing the brush in a location where it can be easily damaged or bent, which could compromise its effectiveness during your next use.
How to Clean Polyurethane Brush
How to clean water-based polyurethane from your brush
Water-based polyurethane is easier to clean from brushes than oil-based polyurethane. This is because it can be easily dissolved in water. If you have a water-based polyurethane brush that needs cleaning, there are a few methods you can use to get the job done.
Here are two effective ways to clean water-based polyurethane from your brush:
Method 1 - Clean with Hot Water
The easiest and most effective way to clean a water-based polyurethane brush is by using hot water.
Start by removing any excess polyurethane from the brush with a cloth or paper towel. Then, run the brush under hot water, using your fingers to work the water into the bristles. Repeat until the water runs clear. This method works best for brushes with synthetic bristles as natural bristles may become damaged from the hot water.
Method 2 - Clean with Hot Water and Soap
Instead of using hot water, you can also clean water-based polyurethane from your brush using soap and water.
First, wipe the excess polyurethane off the brush with a cloth or paper towel. Then, mix a small amount of dish soap with warm water in a container. Dip the brush into the soapy water and swirl it around to loosen the remaining polyurethane. Rinse the brush with clean water and repeat the process until the brush is clean. It is important to avoid using too much soap, as this can leave residue on the brush and affect the finish of your next project.
NOTE: You should always clean your brush immediately after use. This will make the cleaning process much easier and prevent the polyurethane from hardening on the bristles.
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How to clean oil-based polyurethane from your brush
Oil-based polyurethane can be much more difficult to clean from a brush than water-based polyurethane. This is because oil-based polyurethane is not water-soluble, so it requires solvents to remove it.
Here are three methods that you can use to clean oil-based polyurethane from your brush:
Method 1 - Cleaning with Mineral Spirits
Using mineral spirits (white spirit) is one of the most used methods. Mineral spirits are solvents that can dissolve polyurethane and make it easier to remove from the brush bristles.
To clean your brush with mineral spirits, start by pouring a small amount of the solvent into a container. Dip the brush into the container and swirl it around, making sure that the bristles are fully coated with the liquid. Then, use a brush comb or a stiff brush to work the mineral spirits through the bristles and loosen the dried polyurethane.
Once the polyurethane has been loosened, wipe the brush on a paper towel or a rag to remove as much of the solvent and the polyurethane as possible. Repeat the process as needed, using fresh mineral spirits as necessary, until the brush is clean.
NOTE: Mineral spirits can be toxic and flammable, so be sure to wear gloves and work in a well-ventilated area.
Method 2 - Cleaning with Paint Thinner
Similar to mineral spirits, paint thinner can also be used to clean oil-based polyurethane from your brush.
To begin, pour a small amount of paint thinner into a container. Dip the brush into the paint thinner, making sure to coat all the bristles, and swirl it around for a few seconds. You can also use a brush comb to remove any excess paint thinner.
Next, wipe the brush on a clean rag to remove any excess paint thinner and polyurethane. Repeat this process a few times until the brush is clean. Rinse the brush with warm water and dish soap to remove any remaining paint thinner or polyurethane.
NOTE: Paint thinner is highly flammable and should be used in a well-ventilated area. Make sure to dispose of the paint thinner and the rags properly and be sure to wear protective gear such as gloves and eye protection.
Method 3 - Cleaning with Vinegar
Vinegar is a natural and non-toxic alternative to solvents. It works by breaking down the polyurethane and dissolving it. To use vinegar, you will need to heat it up in a pot and then soak the brush in it for several hours. You can then rinse the brush with warm soapy water to remove any remaining polyurethane.
Cleaning with vinegar is a safer option compared to using mineral spirits or paint thinner as it is a natural and non-toxic alternative. However, it may not be as effective as the other methods and may require more time and effort.
Top Products to Clean a Polyurethane Brush
In order to clean your polyurethane brushes effectively, it is important to use the right products. There are many different options available on the market, each with their own unique advantages and disadvantages.
Here are some of the best products for cleaning brushes.
- Klean-strip odorless mineral spirits
- KRUD KUTTER BW32 Brush-Wash Cleaner and Renewer
- Sunnyside Corporation 83432 Mineral Spirits
- Winsor & Newton Brush Cleaner & Restorer
- U.S. Art Supply Brush Cleaner and Restorer
NOTE: Always be cautious when working with solvents!
How to clean dried polyurethane from your brush
If you have a brush that has been left with dried polyurethane on it, don’t worry. There are steps you can take to clean it and soften the bristles:
- Scrape off the excess: Use a scraper or the edge of a credit card to remove any excess polyurethane from the bristles.
- Soak the brush: Place the brush in a container filled with mineral spirits or paint thinner. Leave it there for at least an hour to soften the hardened polyurethane.
- Comb the bristles: Use a comb or brush to gently loosen the dried polyurethane from the bristles. Be careful not to apply too much pressure as it can damage the bristles.
- Wash and dry: Rinse the brush with warm water and dish soap. Gently squeeze out the excess water and reshape the bristles. Finally, let the brush dry in a well-ventilated area before storing it.
Remember, the most important step is to soak the brush in mineral spirits or paint thinner to soften the dried polyurethane. This will make it easier to remove the hardened material without damaging the brush.
In conclusion, cleaning your brushes from polyurethane is an important step in maintaining their quality and prolonging their lifespan.
The methods for cleaning depend on whether you are dealing with water-based or oil-based polyurethane, and each method has its pros and cons.
For water-based polyurethane, hot water, and soap are effective methods, while oil-based polyurethane requires the use of solvents such as mineral spirits, paint thinner, or vinegar.
Remember to wear proper safety gear and work in a well-ventilated area when using solvents!