How to Keep Polyurethane From Drying Out? Tested Way

Have excess polyurethane but not sure how to keep it from drying out?

To keep polyurethane from drying out, you need to ensure an airtight seal of the polyurethane container. To get a tight seal, you should make sure that the lid is not deformed while opening and always clean the rim of the container to remove any dust or debris.

A step-by-step guide on how to store polyurethane the right way to keep it from drying out even when stored for long durations.

Steps to Store Polyurethane Properly- Preventing it From Drying Out

1Open the Container Without Deforming Its Lid
2Stor the Polyurethane in the Right Container
3Wipe the Lid and the Rim of the Container Before Closing the Lid
4Use Bloxygen Spray Before Closing the Lid
5Use a Rubber Mallet to Hammer the Lid Shut
6Store the Container Upside Down
7Store in a Cool and Dry place
Steps to store polyurethane and prevent it from drying

Step 1: Open the Container Without Deforming Its Lid

Opening of the lid of the PU container without deforming it.
Opening of the lid of the PU container without deforming it.

You need to keep polyurethane in a closed container so it doesn’t dry out. To open the original container, don’t use too much force, or you might break the lid.

Use a special tool that can open paint cans. This will help you take off the lid without damaging it, allowing you to close it tightly and keep the polyurethane fresh for later.

Don’t use any generic tool that you use for food cans. It can make the lid bend and not close properly.

Then the polyurethane will dry out, and you can’t use it anymore.

Step 2: Store the Polyurethane in the Right Container

Storing water-based PU in an air-tight container
Storing water-based PU in an air-tight container

Keep the polyurethane in the same container that you bought it in, unless the container is broken or bent.

If you have water-based polyurethane, make sure the inside of the container is not scratched. Scratches can make the container rust and spoil the polyurethane.

If the inside is scratched, you can put the water-based polyurethane in a glass container.

Step 3: Wipe the Lid and the Rim of the Container Before Closing the Lid

Using a clean cloth to wipe the rim of the PU container before closing it.
Using a clean cloth to wipe the rim and lid of the PU container before closing it.

Wiping the lid and rim of the container before closing it can ensure a proper seal.

Any debris or excess finish on the rim of the container can cause the lid to not sit flush and may lead to air getting into the container.

This could cause the finish to dry out or form a skin on the top, making it unusable.

To wipe the lid and rim, use a clean, lint-free cloth or paper towel. Gently run it along the rim of the container, ensuring that all areas are free of debris.

Then, wipe the top of the lid, making sure that no finish or debris remains. This will create a clean and smooth surface for the lid to sit on, allowing for an airtight seal.

Step 4: Use Bloxygen Spray Before Closing the Lid

Using Bloxygen spray is an effective way to remove the air and oxygen from the polyurethane container.

This prevents the polyurethane from drying out and prolongs its shelf life.

The spray is easy to use and can be sprayed directly into the container. Make sure to follow the instructions on the can for the best results.

To use the spray, first, shake the can well. Then, position the nozzle of the spray inside the polyurethane container.

Spray a generous amount of Bloxygen for 2-3 seconds. This will replace the air inside the container with an inert gas, creating a protective layer on top of the polyurethane.

Once the Bloxygen has been sprayed, quickly put the lid on the container and seal it tightly.

This will create an airtight seal and prevent the polyurethane from drying out.

Step 5: Use a Rubber Mallet to Hammer the Lid Shut

Using a mallet to gently force the lid to close properly
Using a mallet to gently force the lid to close properly

Using a rubber mallet to hammer the lid shut can help to create a tight seal that prevents air from entering the container.

Simply place the lid onto the container and position the rubber mallet over the lid.

Then, gently tap the mallet around the edges of the lid until it is securely in place.

Be careful not to strike the lid too hard, as this could deform the lid and compromise the seal.

Once you’ve hammered the lid shut, you can be confident that your polyurethane will stay fresh.

Step 6: Store the Container Upside Down

Another effective technique is storing the polyurethane container upside down.

This helps ensure that there are no leaks along the lid of the container and that any small openings will be shut, preventing air from entering the container and drying out the polyurethane.

Apart from that, storing the container this way ensures that the frozen coat is formed at the bottom and not at the top of the finish.

This makes it easier to access fresh polyurethane every time without having to remove the frozen skin or coat.

Step 7: Store in a Cool and Dry place

Water-based polyurethane
Water-based polyurethane

Proper storage conditions are crucial in extending the shelf life of your polyurethane.

So store it in a cool and dry place to prevent it from degrading or drying out.

The ideal temperature range for storing polyurethane is between 60 and 80 degrees Fahrenheit (15 and 27 degrees Celsius).

Avoid storing it in areas that are too hot, too cold, or humid, such as basements, attics, or outdoor sheds.

Also, keep your polyurethane away from direct sunlight and other heat sources, such as radiators or heaters.

Exposure to heat can cause polyurethane to deteriorate faster, causing it to dry out more quickly.

How to Store a Polyurethane Brush?

Using a microfiber to cover the brush for storing it safely
Using a microfiber to cover the polyurethane brush to store it safely

The brush used to apply polyurethane can be reusable when stored properly.

Polyurethane is a quick-drying finish that can dry and cure on the bristles of the brush, rendering it useless for further applications.

However, you can clean the brush by squeezing the excess polyurethane out of them, followed by soaking the brush in a suitable solvent.

Generally, mineral spirits are used for cleaning oil-based polyurethane, while water-based polyurethane can be easily cleaned with water (Water-Based vs Oil-based Polyurethane).

Soaking the brush for around 10 minutes in the solvent will loosen any dried polyurethane.

You can then clean the bristles of the brush by swirling and scrubbing the bristles gently with your hand.

After removing all the polyurethane from the brush, rinse it with warm water and soap.

Once the brush is clean, you can wrap it in a clean cloth. Avoid wrapping it in plastic, as it can cause moisture to build up and damage the brush.

What is The Shelf Life of Polyurethane?

Storing polyurethane on shelf
Storing polyurethane on shelf

Polyurethane has a shelf life of around one year, but this can vary depending on the type of polyurethane and how it has been stored.

Always check the label or manufacturer’s instructions to see the recommended shelf life for a specific type of polyurethane.

The shelf life can also be affected by factors such as exposure to heat or sunlight, moisture, and contaminants.

Furthermore, following the correct storage technique can maximize the shelf life of polyurethane and ensure that it performs well when used.

Final Thoughts

The ideal way to keep polyurethane from drying is to store it in an air-tight container.

However, the presence of air inside the container can lead to the formation of a dry layer over the finish, which can be removed, and the poly under it can be used.

Apart from that, when using water-based polyurethane, make sure you don’t scratch the inside of the container, as it can lead to rusting and contaminate the finish.

Frequently Asked Questions (FAQ)

Can I store polyurethane in a plastic container?

No, polyurethane should not be stored in a plastic container because it can react with the plastic and cause the finish to become contaminated or degrade. It is recommended to use metal or glass containers for storing polyurethane to ensure the finish remains stable and usable.

Can I store polyurethane in the refrigerator or freezer?

No, polyurethane should not be stored in the refrigerator or freezer as it can cause the finish to thicken or become unusable. Polyurethane should be stored in a cool and dry place with a stable temperature to maintain its shelf life.

How do I know if polyurethane has gone bad?

If polyurethane has gone bad, it will have a foul smell, appear discolored, or have a thick and clumpy consistency. If the finish is not smooth when applied, it may also be an indicator that the polyurethane has gone bad. Before applying the finish to your project, it is best to test it on a small piece of wood to ensure the quality of the finish.