One of the significant challenges of an enthusiastic woodworker is waiting for a polyurethane finish to dry and cure the wood. Although waiting for a natural drying time is the best thing to do, but there are few ways by which you can speed up polyurethane drying time. There are two types of urethane, the oil-based and the water-based counterpart.
How long does Polyurethane take to dry?
The oil-based urethane takes an average of 24 hours to dry after application, while the water-based requires just 6 hours to dry off after application on the wood. However, there is a big difference between the drying time and curing time of the varnish. The curing time is required for your wood to be ready for use after all the finishing processes.
For oil-based Polyurethane, the curing time can take up to a month depending on the weather condition, while for water-based counterpart, the curing time is between 2-5 days. You can start taking back all your furniture indoors or putting back the rug and other floor coverings.
Factors that influence the drying and curing time of Polyurethane
Aside from the fact that water-based Polyurethane dries faster than oil-based, several other factors affect or determine the finish’s drying and curing time. These factors are listed below:
- Type of Polyurethane
We cannot overemphasize the fact that water-based Polyurethane dries and cures faster than oil-based Polyurethane. So, if you want a fast-drying finish, then you should consider getting a water-based polyurethane. Water-based takes just 6 hours to dry and ready for a second finish layer or sanding, while the oil-based will take 24 hours before touching or sanding.
- Kind of Wood
Rosewood and Aromatic cedars are not suitable for the flooring of furniture because they don’t allow crosslinking to occur as fast as possible, which is crucial to Polyurethane’s drying and curing time. However, some woods enhance the drying and curing time of the finish. Selecting a good wood for furniture is essential in determining the curing and drying time of Polyurethane.
- Temperature and Humidity
The higher the temperature and humidity, the faster the drying time of your Polyurethane. It has been proven that at 70F (21 degree Celsius), polyurethane dries at the rate stated above, while at increased temperature, it dries faster, and at the decreased temperature, it takes more time to dry off.
- Wood Surface. A rough surface will not absorb the wood to finish properly. Still, a well-sanded wood surface will absorb the Polyurethane and the finish to dry quickly and be ready for second finish layering or sanding.
Read Also: How Long for Paint to Dry Before Applying Polyurethane Finish?
4 ways to speed up polyurethane drying time
1. Apply a Thinner
Thinning with Naphtha makes Polyurethane dry faster because it has a high evaporating rate than spirit or turpentine. Polyurethane will dry more quickly if the thinner evaporates more quickly, thereby making naphtha the best thinning choice for urethane or any varnish.
2. Use Water-Based Polyurethane
In this post, I have said it severally that water-based Polyurethane dries faster than oil-based Polyurethane. If you need to complete your wood on time, then working with a water-based urethane is your best bet. Six hours after application, the wood will appear dry and not tacky so that you can walk on the finished surface, with socks, of course. You can start subsequent finishing processes like sanding, the second layer (top coating). Give it two days to cure, and then your wood is ready for use. You can start walking barefooted on the finished surface and arranging the furniture and all other stuff carried away from the wood before urethane application.
3. Apply Some Heat
Applying some heat is an ideal way to increase the drying time of Polyurethane. Some people use hair-dryers while some use space heaters or heat lamps. This doesn’t still speed up the wood’s curing time but can make the wood dry faster after applying Polyurethane. On days with higher temperatures, Polyurethane will dry and cure more quickly.
4. Lower the Humidity
The lower the humidity, the faster the drying time of urethane on wood. High humidity will prolong the dry time. You can use room dehumidifiers or clean your AC filter to ensure a steady low room humidity in your workspace for your Polyurethane to dry and cure faster.
Polyurethane Won’t Dry? What to do
Most times, oil-based Polyurethane won’t dry fast, not because it’s a bad finish, but the oil component won’t just dry quickly. If you have a polyurethane finish that won’t dry, it might not necessarily be due to the product used, but it might be due to the wood used containing natural oils, which might make drying longer. To fix a polyurethane that won’t dry, you can apply heat using a heat lamp or blow dryer. This will speed up the drying process.
What are the causes of your Polyurethane not drying, and how to fix it?
There are various things and factors that might affect your polyurethane drying time.
- Natural oils
Perhaps after applying your finish, you realized the Polyurethane is not drying, and that is putting you in a fix. The wood used might contain natural oils, or maybe there’s rubbed oil on the wood’s surface when it’s yet to dry before adding a coat on it. Since you’re dealing with an oily type of wood, you’ll have to wipe off the surface with naphtha or acetone. This will remove the wood’s oiliness, making it easier to dry within a short period.
To fix: To fix an oily wood with a yet to dry polyurethane finish, wipe the surface with naphtha, acetone, or lacquer thinner, then apply the Polyurethane immediately after the solvent dries. Just in case you applied oil to the wood, ensure it dries completely before applying Polyurethane.
- Waiting in between layers
You might end up with a polyurethane that won’t dry when you don’t allow the coats to dry at intervals before adding the next coat. In case you realize the Polyurethane won’t dry with time, you might have to strip off the Polyurethane with a powerful solvent like lacquer thinner, paint stripper, or acetone. After stripping it off, then you can start over to get desirable results.
To fix: to get your Polyurethane dry, you can apply heat using either a heat lamp or blow dryer.
- Giving a short time to drying
Your Polyurethane might have a hard time drying due to not giving it a considerable amount of time to dry completely. It must be left to dry until you can smell the odor coming from the wood surface as it is known that polyurethane finish varies. There is an oil-based and water-based Polyurethane, and due to their features, one has a higher efficiency when it comes to drying.
Oil-based Polyurethane is known to take more time to dry when compared to water-based. For an oil-based polyurethane, after 24hours of applying the finish in the house, you can walk on the floor barefooted with stockings. You can gently walk around the area. Then after 48hours, walking in shoes is allowed.
Your pets can play on the wood surface after two weeks, and after a month, it is safe and dry to use, even to the extent of placing furniture on it, likewise for a water-based polyurethane, which has an advantage over oil based as it dries faster. After 6houts of the application, you can walk with socks, and then after 48hours, you can move in your furniture.
To fix: After staining your wood surface, make sure it dries completely before applying the finishing coats. Also, wait in between coats, at least 24hours before adding another layer of coat.
Conclusion- How to Speed up Polyurethane Drying Time
Temperature and Humidity are crucial factors to consider when checking or speeding up your polyurethane drying time. Therefore, it is vital to increase the temperature and reduce the humidity in the room to enhance the drying time. Using water-based Polyurethane is also very important if you don’t have the patience to wait for its oil-based counterpart’s drying and curing time.
Generally, Polyurethane takes as much as 30 days to cure correctly and absolutely. So the best way not to be too worried about Polyurethane dry and cure time is to apply it about 30 days before the stipulated date you intend to use your wood for any purpose.