It is not uncommon for you to want to apply a polyurethane finish over your freshly painted surface. So, why is that? Well, for me painting your wooden surfaces such as furniture or hardwood floors makes it beautiful. However, polyurethane gives it a different touch, so I wouldn’t crucify you for wanting to add a polyurethane finish over your freshly painted surface. If so, How Long for Paint to Dry Before Polyurethane?
Paints are different, and they come with varying drying times, depending on the brand you are using. Overall, it is appropriate that you allow the painted surface between 24-48 hours to dry before you apply your polyurethane finish. For the best results, however, I advise that you allow the surface up to 72 hours before you can apply your poly finish.
In this case, the key thing is drying; you know your paint better, especially from the instructions issued by the manufacturer. Ensure that you give the paint ample time to dry so that you don’t face subsequent complications.
If you wish, you can even allow your surface to extend slightly past 72 hours of drying.
How to Apply Polyurethane Over Paint
If you are looking to protect your painted surface and add its beauty at the same time, consider applying up to two polyurethane coats over the surface. I advise that you go for a water-based polyurethane formula if you want to avoid yellowing. The good thing about water-based poly formulas is that they dry and cure into a smooth finish. However, they tend to take a lot of time to dry, unlike their water based counterparts.
It is okay to apply a polyurethane finish over any paint, all you need to do is clean the surface and prepare it appropriately before you can apply it.
Here are the steps involved in the application of polyurethane over paint:
NOTE: If you’re applying the formula over fresh paint, ensure that you let the paint cure first. As I stated earlier in this article, the curing times vary depending on the type of paint, and the prevailing atmospheric conditions, on average, allow your surface more than 72 hours to dry and cure.
Step One: Wash Your Painted Surface
In case you are working on a surface that was painted a while back, you should first start by washing it. Use a strong detergent to clean all the grease and other forms of stains on the surface.
Take about 1/2 cup of trisodium phosphate and mix it with a gallon of warm water and scrub the surface using a rag. Cleaning with trisodium phosphate helps degloss the finish, clean it to provide a better surface for polyurethane adhesion.
Step Two: Scuffing of the Surface.
Allow your paint to dry completely; this usually takes at least 72 hours. After it dries, use 120-grit sandpaper to etch the painted surface. Here, you are scrubbing to slightly flatten the sheen on the finish without necessarily making deep scratches that might compromise the appearance of polyurethane. You can choose to etch the surface either by hand or use a palm sander. In case you are applying polyurethane to a painted hardwood floor, scuff the floor using a floor buffer plus a 120-grit sanding screen. After sanding, clear the dust particles using a shop vac for dust collection.
Step Three: Select the Applicator.
Brushing is the best way to apply oil- or water-based polyurethane, alternatively you can choose to apply it by spraying. Rollers are not the best for the application of poly because they leave bubbles that harden with the finish to give an “ugly” look.
You must not thin the polyurethane even if you choose to apply it by spraying. Usually, polyurethane is thin enough to spray straight from the can.
You can use HVLP Spray Gun for Wood Finishing to apply your poly formula by spraying.
Step Four: Apply the First Coat, then Scuff.
After applying the first coat of your polyurethane formula, allow the coat enough time to dry as per the manufacturer’s recommendation. Once the surface dries, use 120 grit sandpaper to scuff the surface slightly. Sanding the surface helps remove small dust particles and flattening bubbles that may have hardened into the finish.
Step Five: Application of a Second Coat.
You can add as many coats as you wish, however, that is more or less like wasting the formula because usually, two coats of polyurethane are enough on your surface. Allow the formula to dry as per the recommendation by the manufacturer. Allow it extra 24 hours to harden until you can consider walking over the surface.
How long Does Polyurethane Take to Dry?
Usually, oil-based polyurethane takes about 24 hours to dry while the water-based polyurethane formula requires only 6 hours to dry enough such that you can walk over the surface using socks while sanding and applying subsequent finishes if needed. Drying time and curing time of polyurethane products are different, curing of polyurethane takes up to 30 days.
Types of Polyurethane and their Drying Time and Curing Time
Oil based polyurethane
- This polyurethane formula takes 24 hours to dry, after which you can freely walk on the floors. At this point, the floor appears dry and not sticky to the touch.
- Ensure that you keep pets off, and if you have to, walk on the floors wearing socks. Do not put on shoes or walk over the surface with your bare feet.
- You can do sanding at this point if you wish.
- If you are interested in adding an extra coat, you can do it after a light sanding.
- After 48 hours, you can walk on the floor with your shoes.
- After at least 4 days, you can gently move furniture back.
- Ensure that you keep your pets away from the surface for 1-2 weeks
- It will take 30 days for the finish to cure fully.
- Water based polyurethane is the quickest drying of the two polyurethane formulas, taking about 6 hours to dry before you can walk on the floors.
- After about 6 hours, your floor should appear dry and not be tacky when you touch it. Keep your pets off and have your socks on if you walk on the floors. Avoid shoes or walking bare feet.
- If you deem necessary, you can sand your surface.
- At this point, feel free to add another coat if it is necessary.
- You can walk on your surface with your shoes on after 24 hours.
- Take at least 2 days before you can move your furniture back.
- Keep your animals away from the surface for at least 1 week.
- The formula takes 30 days to cure fully. Don’t cover your floor for at least 2 weeks.
How to Make Polyurethane Dry Faster
As we already know, a coat of urethane helps preserve and protect your wooden structures for several years. Additionally, it gives the surface a lovely shine that makes the surfaces such as floors and tabletops to stand out. It is quite easy to apply a poly finish; however, it can sometimes take a lot for polyurethane to dry and cure.
Polyurethane formulas dry in two steps. The first is evaporation, where the surface dries first and then curing where the finish hardens and strengthens. If you have the right poly formula and other necessary materials, you can make a poly finish dry and even cure faster.
Here’s how to do that:
- Water-based polyurethane
- Oil-based polyurethane
- A fan
Once you have your materials ready, follow the steps to make your surface dry faster.
Step One: Water Based Polyurethane Over Oil Based
As expected, water based polyurethane formula has a shorter drying time compared to its oil-based counterpart. Therefore, it would be an excellent choice to use the water based poly to help your surface dry faster.
Two coats of this formula will be ready after a little over 6 hours, and you can freely walk on the surface wearing your socks. If you apply two coats of oil based polyurethane, you will have to wait for up to 24 hours for the surface to dry. However, both formulas take more or less the same time to cure.
Step Two: Steady Temperature
You need to maintain working in a temperature range of 50-77 degrees Fahrenheit. At this temperature, polyurethane finds it favorable to dry and cure faster, unlike when the temperature is lower. A higher temperature than this range is not necessarily the best because the formula evaporates more quickly without penetrating the surface. If your region sees high temperatures, you can use an air conditioner to help regulate the temperatures. In case the area is cold, then use a room heater to help keep things warm.
Step Three: Proper Ventilation
Keeping air flowing over the surface with a polyurethane finish is an excellent way to make it dry and cure faster. So how do you achieve this? Well, all you need to do is ensure that the room you are working in has proper airflow. So ensure that you have all the windows and doors opened. Usually, your polyurethane will need about one week to be 90% cured and up to 30 days to cure it entirely.
It would help if you can get a fan on the first day of application and for subsequent days to help you remove fumes that might build up in drying and curing.
Tips to Note While Using Polyurethane
- Ensure that you wear gloves and work clothes every time you are using a poly formula because this formula gets messy, and you’ll find it hard to remove the mess.
- Oil-based urethane formulas release toxic fumes when it is drying and curing. You should, therefore, keep your doors and windows open.
- Water-based polyurethane lasts a shorter duration compared to oil-based polyurethane. Also, it is the most expensive of the two.
Factors the Affects the Drying and Curing of Polyurethane
We have seen that polyurethane is a unique formula that adds beauty to wooden structures and provides protection at the same time. After applying this formula, you may realize it takes a shorter or a longer duration to dry. But what are the factors that affect the drying and curing time of polyurethane?
- The Type of Wood
Woods are different, and when you apply a poly finish to some of these woods, you will realize that the formula takes longer to dry and cure. Some may not even cure because these woods might be producing chemicals that prevent the crosslinking process. Some of the wood types with these properties include rosewoods and some species of aromatic cedars.
- Polyurethane Type
I have mentioned this severally in this article that the type of polyurethane formula that you will use determines how fast or slow the formula dries and cures.
Manufacturers of poly formulas are different, and they use various methods in the creation of these formulas. Some manufacturers will add drying agents while others add oil and many other solvents. Each component of a polyurethane affects the dry and curing time of the formula.
Overall, you will find that the water based polyurethane formulas take a short while to dry compared to their oil based counterparts.
- Atmospheric Temperature and Humidity
The drying time of the polyurethane formulas indicated in this article is dependent on temperatures of 70°F (21°C) per day and 70% humidity. If you are working on a hotter temperature, your finish will dry faster than the ones stated. You should also know that cooler temperatures and wet days will have your formula taking longer to dry.
- The Surface
With raw and sanded wood, your formula will absorb the first coat faster hence shortening the dry time. The very fast coat will wet and seal the surface of the wood. The subsequent coat will take a little longer to dry because you are applying it over another layer.
Watch the video below on how to apply polyurethane over a painted surface:
In this article, we have seen that you can add a polyurethane finish to a painted surface. Even so, you need to ensure that the paint dries before you can add the extra protection and the beauty provided by the poly finish. Applying a urethane over a wet paint can compromise the whole project, resulting in a poor finish, which leads us to a question…
How Long for Paint to Dry Before Polyurethane?
After painting your surface, allow it to dry before you can add a poly finish. Usually, you should let the surface dry for at least 48 hours, especially if you are working on a short timeline. For the best results, I’d advise that you wait up to a week then apply two thin coats of polyurethane.
Having read this post, I hope you found it helpful and have your question regarding the drying time of paint before the application of a poly finish answered. Do you have a question, opinion, addition, or subtraction regarding the subject idea? Feel free to share it with me in the comment section below.