So, you have just used the toughest of clear coatings – polyurethane – to revamp your table’s or any other furniture’s surface. And now you’re wondering how long it’ll take before you can finally use your furniture.
This article will cover how long it takes for polyurethane to dry and cure, factors affecting its drying and curing, and how you can speed up the drying process for your furniture to be ready in no time. First and foremost, let’s look at the difference between drying and curing of polyurethane.
The Difference Between Drying and Curing of Polyurethane
Drying and curing are two different terms when it comes to painting. Drying refers to the point at which the polyurethane feels dry to the touch. That’s the point when the finish stops being tacky, feels smooth, and doesn’t drag when you slide your finger on it.
It occurs when the solvents or water evaporate from the paint. On the other hand, curing refers to the point at which the polyurethane has completely hardened and the surface is ready for use which in this case is a table.
This is because chemical molecules in the paint have had a chance to interact with oxygen, increasing the bond between the molecules.
When the polyurethane has cured, you can put heavy items on it, and it can also withstand scratches on its surface. A common practice to test if the paint has cured is to press your fingernail on the painted surface. If the fingernail leaves an indent, then the paint hasn’t fully cured. Polyurethane typically completely cures between 21-30 days.
How Long Does Polyurethane Take to Dry?
Polyurethane drying depends on the type of polyurethane finish you’re applying to a surface. Other factors also influence the drying time of polyurethane. Let’s look at the different types of polyurethane and their drying times.
1) Water-based Polyurethane
Water-based polyurethane takes lesser time than oil-based polyurethane to dry. It has less odor and doesn’t require a lot of ventilation during application. Most water-based polyurethane finishes take about 2 hours to dry after applying.
After the two hours, you can apply a second coat and lightly sand the surface. This is because the water base evaporates faster than the solvents base in oil-based polyurethane.
Although the water-based finish dries quickly, it requires about 24 hours before the table’s or any other furniture’s surface receives light traffic. If you’ve applied the finish on a wooden floor, it’ll take about 24 hours before you can start walking on it, two days before you can move back your furniture, and 30 days before you can put back the area rug or carpet. Generally, it takes 3-21 days for water-based polyurethane to cure.
2) Oil-Based Polyurethane
Oil-based polyurethane is suitable for high-traffic furniture. That’s because it has a higher resistance to heat, scratches, and chemicals than water-based polyurethane. It takes 8-12 hours to dry before you can apply another coat over it.
This means your project has to extend to a couple of days since polyurethane requires 3-6 coats to get the desired protection and smoothness. It requires a lot of ventilation due to solvents and chemicals present in the paint.
The best time to expose a table or other furniture to light traffic is after 48 hours. A floor painted with polyurethane also requires 48 hours before you can walk on it. Oil-based polyurethane takes longer to dry because of the high amount of volatile organic compounds (VOCs) and the thickness of the finish. It takes an average of 21-30 days for oil-based polyurethane to cure.
3) Spray Polyurethane
Spray polyurethane produces a fantastic and long-lasting finish. Thinning the paint for application creates a buttery smooth finish, leaves fewer texture bumps, and allows it to lay down better. It usually dries to the touch after 2 hours of application. This is when you can apply another coat over it. The surface is ready for light use after 24 hours and completely cures after about three days.
4) Varathane Polyurethane
Varathane polyurethane enhances the wood’s natural grain with high clarity. It also creates a rigid and clear finish, doesn’t yellow with time, and lasts longer than other finishes. It’s divided into two categories of oil-based and water-based polyurethane.
A water-based finish takes 2 hours before you can recoat it, 24 hours for light use, and an extra 48 hours before it can adequately cure for your normal use. An oil-based finish takes 2 hours to dry to the touch, 4 hours before you can apply another coat over it, and 72 hours before you can use it.
Factors that Affect the Drying of Polyurethane
Apart from different types of polyurethane affecting how polyurethane dries, there are other factors at play that influence its drying rate. These include:
- The level of ventilation.
- The amount of humidity.
- Temperature level.
- The type of surface you paint on.
- The sheen type.
- How you apply your polyurethane.
- The formula of the finish.
- The coat’s level of thickness.
What is The Best Temperature for the Application and Drying of Polyurethane?
The temperature of the environment affects the application and drying of polyurethane. If the weather is too hot, the polyurethane finish evaporates quickly and can be a handful when working with it. On the flip side, If the weather is too cold, the polyurethane becomes hard to spread along the painting surface. The ideal temperature range for drying of polyurethane is 70 to 85 degrees Fahrenheit.
How to Make Polyurethane Dry Faster
There are various methods you can use to speed up the drying process of polyurethane if you’re on a short turnaround time. They include:
1) Decreasing the humidity
Reducing humidity in the room you’ve left your polyurethane finish to dry is one way to increase the drying rate. You can do that using a dehumidifier. A dehumidifier eliminates moisture from the air if you reside in a very humid environment. The ideal climate for drying polyurethane is a humidity of below 70%. Painting in a less humid environment can also be of great help in helping the paint dry.
2) Improving the ventilation
Air circulation plays a big part in the drying of the paint. A well-ventilated area not only reduces exposure to the chemicals in polyurethane but also improves the drying rate of the paint. Using a fan enhances air circulation. You can also place it at a close range to the painted surface to aid in speeding up the drying process. However, be careful not to raise dust over the paintwork.
3) Heating the paint’s surface
High temperatures cause the paint to dry faster. Using a hair dryer, heat gun, space heater, or heat lamp does the trick to heat the paint. A warm or hot setting is fine but aggressively heating the surface causes the paint to crack. You can also choose to paint on a sunny day and leave the painted furniture out to dry.
4) By chemical means
An unconventional way of decreasing drying time is using chemical means to increase the drying rate of polyurethane. This includes the use of naphtha. Apart from it being an excellent thinner for paints, stains, and varnishes, it also accelerates the drying process of the paint. That’s because it’s more volatile than mineral spirits and has a higher evaporation rate. Thinning your polyurethane with naphtha before application helps with the drying process.
How Long You Should Wait Between Polyurethane Coats
Different polyurethane manufacturers have distinct waiting times between applications of coats. The first coat of polyurethane usually dries faster than the successive coats. This is because a portion of the first coat soaks into the wood, leaving a small amount evaporating.
The coats that follow bind onto the previous coats instead of soaking, taking longer to dry. The average time between water-based polyurethane coats is 2 hours, while that of oil-based polyurethane is 8 hours. That means you can apply more coats of water-based polyurethane coats in a day than its oil-based counterpart.
What to do After Applying the Final Coat of Polyurethane
The first step after applying the final coat of polyurethane is to check if there are any imperfections on the surface. These can be bubbles, dust nibs, or streaks. If you don’t find any of these, you don’t need to sand the final coat.
You need to wet sand the painted surface if any of the imperfections above are present. Dry sanding is not recommended since it leaves scuff marks and makes the surface look cloudy. Wet sanding, then buffing your polyurethane with a polishing compound produces a glass-like finish.
Using a 400-grit wet/dry sandpaper or sanding sponge, you can wet sand the polyurethane surface. This is after soaking it in water for 24 hours.
There you have it. All you need to know about how long it takes to use your furniture after applying a polyurethane finish. As we’ve seen, the drying and curing of polyurethane depend on a variety of factors. You can also use the various methods we’ve mentioned to speed up the drying process and be well on your way to using your furniture.
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