A coat or two of varnish helps to protect the wood. But before you can enjoy that protection, the varnish has to dry. So how long does this take?
It takes between 6 and 24 hours after varnish application for the varnish to dry. On average, it takes water-based varnish 6 hours to dry enough for recoat and about 72 hours for the varnish to fully cure enough for use. It takes oil-based varnish 24 hours to dry enough for a recoat.
You should leave the oil varnish for at least a week before subjecting it to sanding, use, and cleaning. The ambient temperature, humidity, type of wood, and the number of varnish coats also determine how long it will take for the varnish to dry.
So how long should varnish dry between coats? Let’s find out.
How Long Should Varnish Dry Between Coats?
You should let the varnish dry for at least 6 hours between coats. The dry time between coats means how long to wait before you apply another coat of varnish on an existing coat.
You should know that water-based varnish dries faster than oil-based varnish. On average, a coat of water-based varnish will dry enough for another coat in about 6 hours while a coat of oil-based varnish can take over 24 hours.
The reason water-based varnish dries faster is because of the solvent. Water-based varnishes use water as the solvent while oil-based varnishes use natural or synthetic oil. Since water evaporates faster than oils, the water-based varnish will get dry quicker than the oil-based varnish. So you can re-coat quicker.
To know if it’s dry enough for another coat, feel the texture of the varnish. If varnish feels sticky to touch or gummy on the fingers, the varnish hasn’t dried enough.
You can also try sanding the varnish with a fine-grit sandpaper. If the sandpaper clogs up quickly with varnish, it means the varnish isn’t hard enough. When the varnish is dry enough, the sandpaper will move smoothly.
You can check the container of the varnish to check the manufacturer’s instructions on how long to wait for the varnish to dry before recoat. So now you know how long it takes for varnish to dry. But how long does it take varnish to cure? Let’s find out.
Related Read: Polyurethane Dry Time?
How Long Does It Take Varnish To Cure?
It takes between 24 hours and a few weeks after the varnish was applied for it to cure. On average, water-based varnish cures in less than 48 hours while oil-based varnish cures in about 5 days. It’s usually advised to leave varnish for at least a week to cure and fully harden before use.
You should know that the cure time of varnish has more to do with the temperature and humidity than the solvent in the varnish. This is because varnish cures based on oxidization while drying has to do with evaporation.
For the varnish to cure, dry air (or oxygen) has to get in the varnish causing the particles to oxidize and harden. When the particles in the varnish are completely hard, the varnish is said to have cured.
Cured varnish will be easy to sand and clean. The varnish will also give off very little to no paint fume or smell as the particles are fully dry. When the varnish has cured, it can be used, cleaned, and furniture can be put over the varnish but this will take a few days.
I know what you are thinking. That’s a few days of guiding and leaving the varnished surface unused which can be difficult. So is there any way to make varnish dry faster? Let’s find out.
How To Speed Up Varnish Dry Time?
This guide will show you the best 5 ways to make varnish dry faster, what you’ll need, and how to execute each method. The first on the list is:
1. Using A Hairdryer
Painters use hairdryers to make varnish dry faster every time. Hairdryers generate over 100 degrees Fahrenheit. Heat at that level will make the varnish dry faster.
- Turn on the hairdryer
- Set the heat to medium
- Hover the hairdryer around the varnish coating for a few minutes
- Crank up the heat
- Move the hairdryer over the varnish one last time
- Turn off the hair dryer and let the varnish dry for about 4 hours before recoat.
2. Using Paint Thinner
You can use a paint thinner to make varnish dry faster. This step works best for oil-based varnish and you have to do this before applying the varnish.
To use this method, you’ll need turpentine, mineral spirits, or paint thinner for oil-based varnish and water for water-based varnish. The main reason varnish takes long to dry is that varnish is thick. But if you thin or lighten the varnish, it will dry faster.
- Get a clean paint bucket
- Pour the varnish inside the bucket
- Add paint thinner to the varnish (you can thin the varnish up to 50%)
- Stir the paint thinner and varnish for 90 seconds (stir gently)
- Test the varnish on a small area on the wood to see how it dries
3. By Improving Air Flow
You can also make varnish dry faster by exposing the varnish to cool dry air. You should know that this method works to make varnish cure faster.
- You should open all windows
- Open the doors
- Open the air vents
- Turn on the fans and direct them toward the varnish
- Set the air conditioner to “blow” or “fan.”
All these will increase the airflow around the varnish causing it to oxidize or cure faster.
Here are a few rules and tips to remember while applying varnish:
- Turn on the dehumidifier to reduce moisture content in the air
- Only apply varnish if the ambient or room temperature is above 60 degrees
- Only apply varnish when the humidity is at or lower than 50%
- Don’t apply varnish during the cold winter months
- Thin the varnish before applying it
- Apply light coats of varnish
Now let’s check out some common types of varnish and how long they take to dry.
Different Types of Varnishes and Their Dry Time?
Here are some different types of varnished and their dry time explained:
Spirit varnish dries in less than 24 hours. Spirit varnish dries faster than oil-based varnish because the varnish has no oils. The varnish is made from resin, solvent, and alcohol.
The formula of spirit varnish makes it dry quickly. But you should know that the spirit varnish will take longer to cure. Spirit varnish often cures at about the same time as oil-based varnish.
Acrylic varnish usually dries enough for a recoat in less than 12 hours. Acrylic varnish has one of the fastest dry times among other varnishes. This is because acrylic varnish is a water-based varnish.
Also, the varnish contains low oils meaning that it won’t take long to cure. On average, the acrylic varnish will dry in 6 hours and cure in 24 hours.
It takes exterior varnish about 24 hours to dry enough for a re-coat. This is because exterior varnish is usually coated with extra oils and chemicals to reinforce the varnish to thrive in the harsh exterior environment. These extra chemicals and oils thicken the varnish’s flow making the varnish dry slowly.
You should know that exterior varnish air-dries. This means that the varnish dries based on exposure to dry air. The exterior environment has a lot of dry air so the varnish can get dry to touch very quickly misleading users that the varnish is dry enough for a recoat in a few minutes. This is false.
Even when the varnish feels dry to touch, it’s not strong enough to be sanded or recoated. You should leave exterior varnish for at least 24 hours before recoat and about a week for it to cure.
On average, polyurethane varnish dries enough for recoat in 24 hours, and the varnish cures in about 3 days. You should ensure to sand polyurethane varnish between coats with fine-grit sandpaper to make it stick and dry properly.
Polyurethane varnish takes a while to dry. This is because polyurethane varnish is oil-based. Not just that, polyurethane varnish is a combination of two slow-drying finishes; polyurethane and varnish.
Ordinarily, polyurethane takes several hours to fully cure. When you now combine polyurethane with varnish which also takes hours to dry, you get a finish that would surely not dry quickly.
How Do You Know If Varnish Is Dry Enough?
The following signs will indicate when the varnish is dry enough:
- When the varnish is no longer sticky or tacky
- When the varnish no longer smells
- When the varnish is hard
- When you can sand the varnish without the sandpaper slowing down or clogging up
- When the varnish looks shiny and not wet
- When the varnish reveals the wood grain
- When the varnish causes water to bead
When you notice these signs, the varnish is dry enough to recoat and even sand.
Overall, varnish takes several hours to dry properly due to the thick and oil-based nature of the finish. But you can make varnish dry faster by using the methods discussed above.
If you want a quick-dry varnish, it’s best to go for water-based types. Also, always leave varnish to dry for at least 3 days before using it.