Your wooden project is incomplete without a coating of polyurethane. However, before application, you must understand how long it takes for polyurethane to dry. Since there is a lot of variety among polyurethane products, each has a unique drying and curing time.
If you’re wondering how long it takes for it to dry, follow this guide and find out all you should know about different types of polyurethane and their properties.
Most importantly, no two polyurethanes have the same properties even if they are a part of the same brand. Therefore, do not shy away from getting into details about all the factors that may be affecting your polyurethane’s drying time.
Generally, polyurethane dry time depends on factors such as the type of product you use, the way you apply it, and the influence of external conditions. Even though external conditions are not under anyone’s control, there are ways to increase the drying time of your polyurethane. Water-based polyurethane takes nearly 48 hours to dry, and its oil-based counterpart also takes almost the same amount of time. The only difference is that with oil-based products, the curing process takes longer.
Types of Polyurethane
Before getting into how long it takes for different varieties of polyurethane to dry, it is important to understand the type of product you’re using. Different coatings have a different drying time; therefore, there are a few considerations we must take into account, such as the following.
Oil vs. Water-Based Polyurethane
Understanding how polyurethane is formulated will serve as a great starting point. The coating or varnish of this product is made using polyurethane resins. A liquid solvent is used to dissolve and then carry those resins. It helps create a liquid form plastic. When it comes to the polyurethane liquid base, the two common options are oil or water. Both types are unique in their ways and hence have different dry times.
One of the most important differences between water and oil-based products is their clarity. Even though they both have good clarity, oil-based polyurethane can darken or get yellow over time. Comparatively, a water-based alternative has better clarity for many years.
In terms of safety and less toxicity, water-based polyurethane is a better option. It also contains fewer VOCs, hence, strong odors are not produced. Hence it is much easier to use for your wood projects. Moreover, the drying time is also comparatively faster because water tends to evaporate quickly. The curing time is also comparatively lower because the coating that results from this finish is much thinner. However, you may need to put additional coats as products based on water tend to be less durable.
On the other hand, the polyurethane dry time for oil-based products is slightly higher because, unlike their water-based counterparts, they provide thicker finishes. The amount of oil, along with thickness, increases the duration to dry. However, the finish they provide is much more durable. In terms of VOCs, oil-based products take the lead and can be dangerous due to many chemicals. Moreover, they also result in a strong odor.
Types of Sheen
Now that we’ve established how different types of polyurethanes can differ in terms of properties and drying time, the next step is to understand how different types of sheen can impact the time it takes to dry. Sheen refers to the amount of gloss your polyurethane gives at the end of your project.. There are generally three different types of sheen in polyurethane varnishes outlined below:
- Satin: Satin finishes tend to be less shiny than the others. They provide a matte appearance and minimal shine. Using a satin product results in a faster polyurethane dry time.
- Semi-gloss: This type of polyurethane provides a slightly shinier finish if compared to satin. However, the shine is again minimal and nothing compared to a high-gloss option. It acts as a bridge between flat and glossy and is also a well-liked option among users due to its durability and versatility. It dries at a lower speed compared to satin products.
- High-gloss: A high-gloss varnish offers the most shine out of all the products. Moreover, it is known for its flexibility and durability. You can use this type of polyurethane for both internal and external projects for any wooden surface. However, the only downside is that it takes a long time to dry.
Drying and Curing Time Table
Now that the formulations and basic types have been covered, it is easier to compare them. Again, the total drying and curing time also depends on factors such as humidity, and temperature along with the type of surface.
- Water-based polyurethane takes 8 hours to be set for the next layer, whereas oil-based polyurethane takes 24 hours.
- Water-based polyurethane takes about 24 hours to get completely dry, whereas the oil-based alternative takes about 48 hours.
- In terms of placing heavy items on the finished surface, it takes two days for a water-based product to be ready instead of 4 days with an oil-based product.
- To be fully and completely cured, a water-based product takes 20 days as opposed to 30 days with an oil-based product.
However, it’s better to hold back for at least a month before placing any items containing plasticizers on your finish as they can leave spots on your surface.
Difference Between Drying and Curing
When referring to the polyurethane dry time, it is important to note the difference between curing and drying processes. When polyurethane dries, it does not mean it’s cured. Therefore, to understand how long it takes for polyurethane to dry, we must understand the basic difference between the two.
Drying refers to the hardening of the external polyurethane finish. It means that your polyurethane is not wet or tacky anymore. However, it does not mean that it is fully ready. It is also possible for your dried finish to get damaged if you put a lot of pressure on it. It is recommended to avoid using your surface, such as a countertop, for any heavy work after it has just dried.
On the other hand, curing is a slightly time-consuming process where your polyurethane dries and hardens completely. It happens when your polyurethane goes through an oxygen reaction after exposure to it. Therefore, curing refers to the final result in a firm and harm form. As the surface is cured completely, you can put a regular amount of pressure on it. Since the curing process is time-consuming, it usually takes a day to a month to complete.
What Factors Can Affect Curing Time?
Several external factors cause polyurethane to dry differently. The drying time, however, will change if you put the same product in different types of conditions. Some crucial factors that determine your polyurethane dry time are:
External temperature is an extremely crucial factor when you apply a finish on wood. The ideal condition should be anywhere near70 degrees Fahrenheit. The polyurethane tends to take long to dry if the weather is extremely cold. This is because, in colder conditions, an odd white film can develop over your polyurethane affecting its drying time. Hot temperatures are also a problem when it comes to the overall finish.
Another important factor that’s often overlooked when it comes to your polyurethane’s dry time is the applied layers’ thickness. In simple terms, your polyurethane finish could take much longer to dry if the coats are thicker. It is also influenced by some more factors such as: the product used and the application method.
Painting polyurethane using a brush can make the outcome appear slightly thicker; hence it also takes longer to dry. On the other hand, if you use a spray or roller, your layers will be much thinner. This results in a faster drying time comparatively. To achieve thin and fast-drying layers, you can also purchase products that allow you to wipe-on.
The type of product you use can also influence the thickness of your finish. For instance, oil-based products are thicker compared to water-based products. Therefore, if you want a thinner finish with a faster drying time, go for a solution that’s water-based.
For ideal results after applying polyurethane finishes to the wood, the humidity should be between 50 to 70 percent. This is because if the humidity is high, your finish may not be able to dry properly, resulting in a below-par final product. Therefore, if humidity is a significant issue, it is best to go for oil-based polyurethane because water-based products tend to be more sensitive to humidity.
What Causes It to Dry Cloudy?
Before we jump into factors behind a cloudy finish, it’s important to note how many coats you must apply for protection. It is generally recommended to apply a minimum of two coats for protection unless the surface in question is a floor or anything susceptible to moisture. In that case, it is recommended to apply three coats.
Sometimes, when you don’t take the humidity factor in mind and apply shellac, lacquer, or another quick-drying finish, it can turn milky. This is because moisture is trapped in the finish, and it does not get the chance to evaporate before the finish gets harder.
Tips and Tricks for a Faster Drying Time
Now that the factors that influence drying and curing time are clear, we can look into some tips and tricks to make your polyurethane surface dry quicker. Moreover, if you find yourself struggling with your polyurethane dry time, refer to the following tips below:
Ø In freezing conditions, use a source of heat to increase the speed of the process. For example, you can use a hairdryer to heat your surface quickly. However, make sure to apply it gently, as applying too much of it can affect your final finish.
Ø If you feel that the polyurethane has become thicker, it can be made smooth so it can dry quickly. You can use a roller to create thin and even layers. Additionally, it also allows your coating to be smoother.
Ø Don’t forget to look out for the weather. Even though it sounds odd, weather can play a huge role in applying polyurethane outdoors. You can know for sure if there’s any humidity or rain expected so you can schedule your project for later.
Ø Keep in mind that polyurethane that is water-based is much more susceptive to humidity as compared to its oil-based alternative. Therefore, it’s better for humid conditions to use the latter since it dries faster in such conditions. This will give you a lasting coat for long.
Ø Prepare your surface well before you plan to apply the polyurethane. Make sure to clean, sand, and polish your wooden surface as it will settle and dry the polyurethane well.
How Long Do The Polyurethane Layers Take to Dry?
The polyurethane dry time is also affected when you apply paint in layers. It is as important that you understand the factors stated earlier. This is because when the finish is applied, you may have to apply it in multiple coats.
You must check when the last coat is completely dry for you to apply the next layer. Knowing when to apply the layers depends on knowing what the difference is between dry and cure times.
When the first layer is applied, expect it to take anywhere between one to eight hours to dry. However, as it has already been established, drying does not mean curing. Therefore, drying would simply mean that your layer is just dry enough to touch. If your finish has reached that stage, the second coat can be applied.
Putting the third coat also requires the same rule. However, once you have applied the latest coat, leave your polyurethane for curing completely before you use it.
If you wish to apply it in thin layers, use a paint sprayer. However, ensure that the spray you have is able to handle polyurethane. If it cannot handle polyurethane, you can roll or paint on your surface as recommended.
What Can You Do if Your Polyurethane Won’t Dry?
Most oil-based products don’t dry fast because of the oil component in them, not because it’s a bad product. If you have a polyurethane product that won’t dry, it may be due to the wood and not the product itself. Wood contains natural oils that make the drying process longer.
To fix polyurethane that’s giving you a hard time to dry, you will need to make some effort. You can start by applying heat using a blow dryer or heat lamp as they speed up the drying process.
If you’re still struggling with the same problem, you might want to look into the causes or factors making your polyurethane dry slower than usual. Some factors behind a slower drying time are:
There are chances that the wood you are using contains natural oils. If it is not natural, there may be rubbed oil on its surface that you should let dry before adding a coat of polyurethane. Since the type of wood you are dealing with is oily, you will have to wipe the surface off with acetone or naphtha. This will help remove the oil on your wood, making it easier to dry. Apply the polyurethane as soon as the solvent dries.
Waiting Time between Layers
Another possible cause of your polyurethane not drying could be the amount of waiting time between layers. When you add the first coat to a surface, you must let it dry for some time before adding the next coat. If you find your polyurethane not drying with time, it’s better to strip it off with a strong solvent like acetone, paint stripper, or lacquer thinner. Once it is completely stripped off, start the process over to get the results you want.
Giving Insufficient Time to Drying
Sometimes, the reason your polyurethane doesn’t dry well enough because you may not be giving it enough time to dry completely. You must leave it to dry until you are able to smell the odor coming from your wood surface because every polyurethane finish varies.
Since we have already established the differences between water and oil-based products, it is a well-known fact that water-based products dry quicker than oil-based products. After 24 hours of applying oil-based polyurethane finish in your house, you can walk around gently but without shoes. Walking with shoes on is allowed after 48 hours have passed.
Dry Time on Hardwood Floors
Wooden flooring is one of the most popular choices for applying polyurethane. As mentioned previously, several external factors impact the drying time on wooden floors. Water-based products are usually dry in 6 to 8 hours and cure in around 48 hours. However, before you walk on your newly finished floors, make sure to wait for at least 24 hours.
Dry Time for Oil-Based Products
Generally, oil-based products take 24 hours to dry, but for some products, it can also be 48 hours. Therefore, keep the conditions of application in mind to have a better idea for duration.
On the whole, before starting a new woodworking job, you must have enough knowledge about polyurethane dry time. In short, different varieties of polyurethane offer drying times. You must know the differences well before choosing to buy a product. Depending on the type of project, if you are willing to wait longer and get your desired results, get oil-based polyurethane.
However, if your project demands quick results, you can choose to go for a water-based product based on the temperature, humidity, and layer thickness. Needless to say, whichever product you choose, understand the needs of your project and your budget before making the final call. Through our guide above, you will be able to differentiate between products and their properties to choose the one that fits your wood project the best.
Frequently Asked Questions
What Is the Curing Time for Polyurethane That Is Water-Based?
Water-based products usually take between 24 to 70hours to cure fully. The drying time is usually 6 hours, but it depends on the environment and the type of product used.
How Can I Speed up the Polyurethane Dry Time?
You can speed up the drying process by changing the layer thickness or making the temperature ideal. The best temperature is 70 degrees, but there shouldn’t be a lot of humidity.
How Long Would Minwax Polyurethane Take to Dry?
Most people naturally wonder how long this product takes to dry since it is a renowned brand. The drying time for this product depends on external conditions and product specifications. There are certain products within the brand that dry within 4 to 6 hours.
What Happens if You Don’t Sand Before Applying the Next Polyurethane Coat?
If you fail to sand between polyurethane coats, it does not significantly impact the finish. However, it’s still recommended to do so as the adhesion between layers will increase, giving you a more level finish.
How Can I Know When My Polyurethane Is Dry?
There are many ways to know when your surface is dry. With oil-based products, you can know it as soon as the tackiness is gone and you can no longer feel a smell. With water-based products, you can know for sure once they don’t feel cool to the touch. With light sanding, a powder will also form.