Polyurethane is a popular finish used in woodworking to protect the surface of the material and is generally preferable to be applied using a bristle brush to prevent bubble formation.
However, cleaning polyurethane from brushes can be a daunting task as it dries quickly and hardens on the bristles.
You can clean a polyurethane brush by soaking it in a cleaning solvent for around 15 minutes, followed by agitating the brush to remove the polyurethane from its bristles and rinsing it under running water. Generally, oil-based polyurethane brushes are cleaned in mineral spirits, while water-based polyurethane brushes in water.
In this article, we will discuss various methods to clean polyurethane brushes effectively and the right way to store a polyurethane brush between coats.
Polyurethane finish hardens when left to dry, rendering the brush useless for future applications.
This makes it important to clean the brush regularly without allowing it time to dry and cure.
The process of cleaning a polyurethane brush involves some basic steps that can be followed to get a clean and soft brush, ready for future projects.
Apart from that, you can also follow a similar process for cleaning a roller used for applying polyurethane.
However, cleaning a roller can be significantly difficult, and is generally advised to use a disposable foam roller.
| Steps | Description |
|---|---|
| 1 | Gather your Supplies |
| 2 | Remove Excess Polyurethane |
| 3 | Pour the Cleaning Solvent into the Container |
| 4 | Soak Brush in Cleaning Solvent |
| 5 | Swirl and Agitate the Brush |
| 6 | Rinse the Brush |
| 7 | Dry the Brush |
| 8 | Store the Brush |
To clean your polyurethane brush, you will need a cleaning solvent, a clean container, some old rag, and a pair of gloves.
Make sure that the container is large enough to hold the brush without bending the bristles.
Before cleaning your brush with mineral spirits, remove any excess polyurethane by wiping it off with a clean rag or paper towel.
Be careful not to bend the bristles or damage the brush, especially if the brush has natural bristles. Synthetic bristles won’t be as damaged easily.
Generally, water-based polyurethane is comparatively easier to clean than oil-based polyurethane.
You can try using a brush comb if the residue is not coming off. It can reach hard-to-reach areas and remove those stiff residues.
Once the excess polyurethane has been removed, pour sufficient cleaning solvent into the container to cover the bristles of the brush.
Generally, mineral spirits, acetone, or paint thinner are used as cleaning solvents for removing oil-based polyurethane from the brush.
Whereas for cleaning a water-based polyurethane brush, you can fill the container with warm water and add a small amount of dish soap or mild detergent.
Add only 2-3 drops of dish soap to the water, as adding too much soap can make it difficult to rinse the soap off the brush.
Place the brush into the container and allow it to soak for 15 to 20 minutes. The cleaning solvent will dissolve the polyurethane and loosen it from the bristles.
After a few minutes of soaking, you can gently push the brush against the bottom of the container to check if the bristles are starting to soften up.
If the polyurethane on the brush is completely dried up and hardened, allow the brush to sit in the solvent for over an hour.
After the brush has been soaked, swirl it around in the container to help loosen any remaining polyurethane.
You can also use a wire brush to gently agitate the bristles to help remove any stubborn bits of polyurethane.
Make sure not to apply strong force when using the wire brush, as it can damage the bristles of the brush.
If the brush still contains bits or residue of polyurethane, repeat steps 1-5 until the brush is clean and free of any polyurethane residue.
After you have swirled and agitated the brush to ensure there is no residue of polyurethane, remove it from the cleaning solvent and rinse it with warm water.
You can also use dish soap to rinse the solvent off the brush.
Be sure to rinse the brush thoroughly to remove any remaining soap from the brush, as it can affect the quality of your next project with that brush.
Once the brush has been rinsed, gently shake off any excess water and lay the brush flat on a clean rag to dry. Make sure not to bend the bristles, as it can damage the brush.
After ensuring that the brush is completely dry, you can store it in a dry, cool place, ready to be used for your next project.
It’s important to note that when using mineral spirits or paint thinner to clean your brush, you should always wear gloves and work in a well-ventilated area.
This is because mineral spirits are flammable and can be harmful if inhaled or absorbed through the skin.
Polyurethane is a synthetic resin commonly used as a protective coating on woodworking projects.
However, the durable coating can be challenging to remove from paint brushes due to several reasons.
Polyurethane dries relatively quickly, making it difficult to remove from paint brushes once it has dried.
If left to dry on a paintbrush, the polyurethane can harden, making it challenging to remove even with a solvent.
Polyurethane is highly resistant to most solvents, including those commonly used to clean paint brushes.
This means that sometimes even if you use solvents such as mineral spirits or paint thinner, they may not be able to dissolve the polyurethane, making it challenging to remove.
If you use the same brush repeatedly for polyurethane application without cleaning it properly, the polyurethane can build up on the bristles.
This build-up can make it difficult to remove the polyurethane.
Polyurethane coating takes around 2-4 hours to dry completely before being ready for a second coat.
Leaving your brush around for such a long time without cleaning will result in the hardening of the bristles, requiring a tedious cleaning procedure.
However, if the waiting time is around 15 minutes, you can place the brush inside the polyurethane solution to prevent it from being exposed to the atmosphere.
Generally, it is advised to submerge the brush in such a way that the polyurethane solution entirely covers the already existing polyurethane on the bristles of the brush.
On the other hand, if you’re taking a longer break, be sure not to leave the brush exposed to the atmosphere.
Although wrapping the brush in plastic can slow the hardening process of polyurethane, it is not advised to leave the brush covered in plastic for longer durations.
Instead, clean the brush thoroughly by following the proper procedure and store it in a cool, dry place.
Once the brush is clean, gently shake off any excess water and reshape the bristles with your fingers.
To store the brush, wrap it in foil or store it in a brush keeper or brush holder. Avoid storing it in a plastic bag, as this can trap moisture and cause the bristles to become brittle.
Finally, when you’re ready to use the brush again, clean and dry the brush again before applying the polyurethane.
Polyurethane is a quick-setting resin that can stick to the bristles of the bush, making it difficult to clean.
However, with proper procedure and the right cleaning solvent, you can remove the polyurethane from the brush and regain the softness of the bristles for future projects.
Generally, mineral spirits are recommended for cleaning oil-based polyurethane from a brush, while dish soap and water can be used to clean a water-based polyurethane brush.
Yes, vinegar can be used to clean a water-based polyurethane brush. Vinegar is a natural and non-toxic cleaner that can effectively dissolve and remove any residual polyurethane on the brush bristles.
Yes, you can use gasoline to clean a hardened oil-based polyurethane brush. However, it is not advised to use gasoline as any residue of gasoline in the brush can lead to the risk of fire by dissolving in the polyurethane during the next project.
No, it is not recommended to use an oil-based polyurethane brush to apply water-based polyurethane. This is because the oil in the brush can contaminate the water-based polyurethane, resulting in poor coverage, streaking, and potentially causing adhesion issues.
