Before you can enjoy the benefits of a polyurethane finish, the polyurethane paint needs to dry first. So how long does this take?
It takes water-based polyurethane between 12 hours and 24 hours to dry. On average, water-based polyurethane will dry enough to touch and handle in 8 hours.
To re-coat, water-based polyurethane needs to dry for at least 12 hours. To cure, water-based polyurethane will take at least 24 hours.
Oil-based polyurethane however takes longer. It takes oil-based polyurethane between 24 hours and 48 hours to dry. On average, oil-based polyurethane will dry enough to touch and handle in less than 24 hours.
To re-coat, oil-based polyurethane needs to dry for at least 24 hours. To cure, oil-based polyurethane will take at least 3 days. This post reveals more about the dry and cure time of polyurethane. So let’s dive in.
How Long Should Polyurethane Dry Between Coats?
You should let oil-based polyurethane dry for at least 6 hours between coats. Water-based polyurethane can be re-coated in about 4 hours or less. The time it takes for polyurethane to dry between coats means the time to wait before applying a second coat of polyurethane.
If you apply a second coat too soon, the polyurethane will not adhere well because there will be solvents trapped in the paint coating. Also, the finish will not come out as clear as polyurethane is supposed to.
You should know that there are several types of polyurethane and each type has a distinct drying time. For instance, satin polyurethane will dry faster than high-gloss polyurethane even if both paints have the same base or solvent. This is because the additives that make up the glossy layer in the high-gloss polyurethane will prolong the drying time of the finish.
Before you can apply a second coat of polyurethane, the existing coat has to dry completely and not just to touch. This means the solvent in the polyurethane has to be completely evaporated.
The main reason for this is because polyurethane is usually sanded between coats. Sanding between coats of polyurethane helps to achieve a smooth and well-bonded surface.
But if the first coat hasn’t cured, you can’t sand it. If you do this, you will scar and remove the first coat. So it’s advised to let the polyurethane dry enough to be sanded and then re-coated.
So how long does this take? Let’s take a closer look.
How Long Does Polyurethane Paint Take To Cure?
On average, It takes water-based polyurethane 24 hours to cure. Oil-based polyurethane takes at least 48 hours to cure.
The curing time refers to how long to wait before the polyurethane finish can be subjected to daily use and cleaning. For polyurethane to cure, the solvent should have completely left the paint coating. Not just that, the paint particles in the polyurethane must have bonded and hardened.
Most DIYers mistake paint curing for drying. For paint to dry, the solvent in the paint coating has to be completely evaporated. Polyurethane paints use either oil or water as the paint solvent.
Since water evaporates faster than oil, water-based polyurethane will dry faster than oil-based polyurethane. So the drying time of polyurethane is based on the rate of evaporation.
The curing time however is based on the rate of evaporation and oxidization. After the solvent has evaporated from the polyurethane completely, oxidization follows. Oxidization is a process where the chemical particles in the polyurethane coating react to the oxygen in the atmosphere.
This reaction causes the polyurethane to harden and this process can take as little as 24 hours for water-based poly to over 3 days for oil-based poly. Oil-based high gloss polyurethane can take up to 7 days to fully cure.
It’s usually advised to allow the polyurethane to cure fully before sanding or using it. While the polyurethane might be dry to touch in a few hours, this doesn’t mean it can be used just yet. If you place items on or walk over polyurethane that hasn’t cured, the finish will be ruined.
However, not everyone has the patience to wait hours to allow the polyurethane to dry and cure. So how can you make polyurethane dry faster? Let’s find out.
How To Make Polyurethane Paint Dry Faster?
There are several ways to make polyurethane dry faster. This guide will reveal the top 5 ways to increase the drying time of polyurethane so you can re-coat and use the finish sooner. The first on the list is:
Method 1: Use Paint Thinner
One of the best ways to make polyurethane dry faster is to thin the polyurethane. Polyurethane has a thick flow and painting 101 teaches us that thick paints will have thick coats and thick coats take longer to dry. So to reduce the drying time, thin the poly. Thinning poly means making the paint lighter.
To thin polyurethane, you’ll need:
- A solvent
- Paint mixer
- A paint bucket
Here is how to thin polyurethane:
1. Pour The Polyurethane Into a Paint Bucket
Pour the polyurethane from the container into a clean paint bucket. Ensure there isn’t any moisture or leftover paint in the paint bucket.
2. Add Paint Thinner
Next, add paint thinner to the polyurethane. Water-based poly should be thinned with water. Oil-based polyurethane should be thinned with a petroleum distilled solvent. Mineral spirits or turpentine work fine to thin oil-based poly. Ensure not to add too much paint thinner.
3. Stir The Mixture
Next, use a paint mixer or turning stick to stir the polyurethane. Ensure to stir until you have even paint flow, consistency, and color.
You should know that this method doesn’t work for spray polyurethane as you can’t thin paint in a spray container.
Method 2: Use a Hairdryer
Since polyurethane dries through evaporation, you can increase the heat around the paint coating after applying it to increase moisture loss. For this method, you’ll need:
- A hairdryer
Here is how to make poly dry faster using a hairdryer:
1. Plug-In The Hairdryer
Plug-in and turn on the hairdryer. Then set the hairdryer heat to medium.
2. Hover or Move The Hairdryer Over The Polyurethane Paint.
Ensure the hairdryer doesn’t come in contact with the poly. Keep the hair dryer about 8 inches from the polyurethane surface. Also, move the hairdryer from side to side. Don’t keep it over one spot as that can cause the poly to dry unevenly.
3. Leave the polyurethane to dry
You shouldn’t dry the polyurethane completely with the hairdryer if not the coating will dry too fast and peel off. You should only use a hairdryer over the polyurethane for a maximum of 10 minutes.
Next on the list is to…
Method 3: Lower Room Humidity
This hack especially works well for water-based polyurethane. If the moisture content in the atmosphere is more than 50%, polyurethane will struggle to dry as the humid conditions will affect the paint coating. For this method, you’ll need:
- A dehumidifier
Here is how to make polyurethane dry faster using this method:
1. Plug In and Turn On The Dehumidifier
Turn in the humidifier based on the manufacturer’s instructions. The dehumidifier will draw in air, condense (or remove) the moisture in the air, and release dry air into the atmosphere. This will prevent moisture from settling on the poly.
2. Keep The Dehumidifier Running
The good thing about dehumidifiers is you can keep them on for hours. The longer it’s on, the faster the paint will dry. The next method is to…
3. Allow Proper Room Ventilation
Before painting polyurethane, ensure to open all windows and doors to allow proper air circulation. When air is being circulated properly, the rate of evaporation and oxidization will increase. This method works well when the polyurethane coating is curing. It also helps you re-coat faster.
The last method is to…
Method 4: Apply Thin Coats of Polyurethane
Most people prefer to apply thicker coats of poly believing that the thicker the paint is applied, the stronger and more durable the finish will be. This is false. Thick poly coats don’t dry quickly as the rate of evaporation will be very slow. Also, thick poly coats are very difficult to control.
By applying thin coats of polyurethane, you reduce the level of evaporation and oxidization needed before the paint can cure. This makes the poly dry sooner.
Other tips that can help polyurethane dry faster include:
- Using water-based polyurethane. Oil-based poly takes longer to dry.
- Applying the polyurethane early in the day before the weather gets hot.
- Turning on fans in the room while applying the polyurethane.
- Applying the polyurethane in proper painting conditions. Humidity should be less than 50% and temperature should be between 50 and 80 degrees Fahrenheit.
So how do you know when polyurethane is dry? Let’s find out.
How Do You Know If Polyurethane is Dry?
Polyurethane becomes dry when the finish is no longer tacky or when the finish doesn’t have a wet appearance. When polyurethane is still fresh or wet, the polyurethane will be very shiny or reflective.
This shows that there is still moisture or solvent in the paint coating. The moisture in the poly is what is making the paint coating very reflective to light.
If the polyurethane is dry, it wouldn’t be very shiny or reflective. Instead, the finish will be glossy. Satin polyurethane, however, will not be reflective or glossy when the paint dries but can be reflective if the paint is still wet or fresh. This is because satin polyurethane has no gloss.
You can also test the paint coating by running your fingers across the finish. If the polyurethane is dry and smooth, then the coating has dried. However, to know if polyurethane has cured, you can try wiping the polyurethane with a damp rag.
If the polyurethane hasn’t cured, the rag will have light stains on it. This shows that the polyurethane isn’t water-resistant yet and a major feature of cured polyurethane is that it is moisture-resistant meaning it can’t be wiped off with a damp rag.
What Happens If You Re-Coat Polyurethane Paint Too Soon?
If you re-coat polyurethane too soon, the second or third coat will not stick well to the existing coating. This is because there will still be moisture (oil or water) trapped in the polyurethane coating. The trapped moisture will repel the second coat.
Also, re-coating polyurethane too soon will cause the finish to be uneven, blurry, and tacky for several days.
When you re-coat polyurethane too soon, what happens is that the existing coating will not be given enough time to dry and cure. This means that the process of evaporation and oxidization will still be halted in the polyurethane paint coating while a second coat is over it.
Since evaporation and oxidization are stopped, moisture will be trapped in the polyurethane. The trapped moisture will prevent the second coat from adhering properly and the entire finish will come off sooner than later.
Also, trapped moisture will bleed through. When a second coat is applied, it seals the existing coat. And, since polyurethane is water-resistant, the trapped moisture will have nowhere to go but bleed through the second coat.
This will cause stains and uneven drying. If the polyurethane was tinted, re-coating too soon will cause the color to become semi-solid or tacky.
How Long Should Polyurethane Paint Dry Before Use?
You should let the polyurethane paint cure before using it. This will take between 24 hours and a week depending on the type of polyurethane that you applied. Exterior polyurethane should be left to cure for at least a week before it is used.
When the polyurethane has cured, it can be used, walked on, re-coated, and even sanded without the paint coating wearing off.
If you use poly too soon, you’ll wear the finish. Tinted poly that is used too soon will bleed through and develop stains.
The Drying Time Of Polyurethane (Chart)
Here is a tabular summary of the drying time of polyurethane:
|Water-based polyurethane||Oil-based polyurethane|
|Dry to touch||8 hours||24 hours or less|
|Dry enough for recoat||12-24 hours||24 – 48 hours|
|Curing time||24 - 48 hours||3 days – 1 week|
|Dry enough to use and wash||Minimum of 3 days||Minimum of 5 days|
Overall, polyurethane paint on average takes about 6 hours to dry, 24 hours to re-coat, and 48 hours to use. Before the finish can be cleaned or washed, it’s best to wait for a week.
However, you can make the paint dry faster but it’s best not to alter the drying time too much as this can cause the polyurethane to crack, peel off, or blister off.