Polyurethane is a type of varnish that will protect your floor from scrapes and wear. Applying one or two coats of polyurethane over the painted floor is a good way to protect the paint.
Use a water-based polyurethane to protect the color because it will not be yellow as much as an oil-based one. Use oil-based polyurethane for a smoother finish, but it takes several hours longer to dry.
Apply polyurethane on top of paint of any type after cleaning and proper preparation. You can also apply it on a wooden surface to create a unique look.
Here you will know how to apply polyurethane over the painted floor and how long you should wait for the paint to dry before applying a polyurethane finish.
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How to Put Polyurethane Over Painted Floor?
Before applying the polyurethane, you must thoroughly clean the surface to eliminate dust. After this, put a thin coat and smooth the surface with any rolling tool. Leave this finish to dry and use grit sandpaper to eliminate brush marks or dust nibs.
You will notice sand residue, which should be removed again with a quick cleaning session. Now apply another coat of thin polyurethane and follow the same procedure again. If you prefer water- based over old-based polyurethane, you can apply at least two or three coats for a smooth finish.
Consider This Before Applying Polyurethane
Keep the below-mentioned factors in mind before you plan to apply a coat of polyurethane over the painted floor:
The first thing that will determine how quickly paint dries is heat. The optimal temperature for drying is between 70 to 77 degrees Fahrenheit.
When the temperature drops below 50 degrees Fahrenheit, the paint structure may begin to fail. Use a heat fan or a thermostat, set the temperature at 70° F, and leave the room while the paint dries.
Heat and air both help liquids dry faster. Proper ventilation will increase the drying time, and a lack of ventilation will slow it down.
If you are painting in a limited space, use a fan to speed up the drying process and get rid of the fumes.
The excess moisture can be absorbed into the wood, releasing bubbles when you paint over it. Humidity also slows down the drying process because it adds more water to the liquid that’s trying to evaporate.
Use a hygrometer to measure the level of humidity. A good range is between 50% – 70%. To control excess moisture, use a dehumidifier. If the problem is too little moisture, use a humidifier.
Depending on the type, shade, and brand, some paints dry quicker than others. In general, darker colors dry slower than lighter shades.
Different types of paint dry and cure at different rates:
It dries in 30 minutes, but you should wait at least a day before applying a second coat. It takes 30 days to cure.
It dries in 30 minutes and needs 30 days to cure.
It dries in 4 hours and can be fully cured in 21 days.
It dries between 6 to 8 hours and takes at least 30 days to cure.
It dries in about 8 hours.
Some woods have high chemicals that prevent the paint from sticking properly and evaporating. Rosewood and cedarwood can be difficult to paint.
Preparation for Putting Polyurethane
- If you are coating fresh paint, allow the paint to cure first. Curing times vary according to paint type and atmospheric conditions, but the average time a paint takes to cure is about a week.
- Lightly sand the paint with 120 grit sandpaper to flatten the paint. Make sure to remove all dust before applying your finish.
- If you are re-finishing an item that has previously been waxed, you will need to remove the wax before applying your polyurethane. To do this, wipe the surface down with mineral spirits with a soft cloth.
- If there is any grease on the surface, clean it well.
How to Apply Polyurethane Over Paint
Follow these steps to apply polyurethane over paint just like the pros:
Clean the Surface
Polyurethane does not stick properly to greasy surfaces. Clean the painted surface thoroughly with detergent or trisodium phosphate (TSP).
TSP is a powerful cleaning product. Use it to clean old stains and detergent for a recent application. Wear safety glasses and rubber gloves when using TSP to protect yourself.
Sand the Surface
Use 120-grit sandpaper to get rid of any deep scratches on the surface of the wood. Sand to even out the shine in the paint. Use a palm sander if you can’t get a flat smooth surface manually with 120-grit sandpaper.
Clean the Residue
Clean the sanding residue using a cloth or a top-of-the-line vacuum such as shark vacuum cleaner. Make sure there is no trace of dust left, or it will ruin your polyurethane application.
You can dip a fur-free cloth in water and use it to clean the surface. This method gets rid of dust better, but you let it dry before the next step.
First Coat of Polyurethane
Apply a thin polyurethane clear coat to the surface, whether oil-based or water-based. You can use any tool to apply the first coat – a brush, roller, pad, or spray.
Use a clear spray coat for wood. Once you are done, leave the polyurethane finish to dry. Some surfaces need only one coat of polyurethane if the surface gets smooth.
Sand After Drying
Once the polyurethane varnish is dry, use 220 grit sandpaper to smoothen the surface. Remove all the dust nibs, brush marks, or other imperfections such as deep scratches.
You may use a bag vacuum cleaner to clean wood floors by removing the dust and debris.
Follow the same method mentioned above to get rid of the sanding residue and small dust particles.
Second Coat of Polyurethane
The first coat is not always enough. Apply another thin coat of polyurethane, using the same process as above.
Wait for it to dry, then repeat the sanding and cleaning steps until you achieve the desired level of smoothness. Apply two or more coats, especially for water-based polyurethane.
How to Know if Paint is Dry or Cured?
There are two ways to determine if the paint is dry or cured. These ways are:
To Determine if the Paint is Dry
Firmly touch the paint’s surface in an isolated area. If the paint is not sticky, then it is dry.
To Determine if the Paint is Cured
Push the paint with your fingernail. If your nail leaves a mark, then the paint is not cured. However, if there is no mark, the paint has fully cured.
FAQs – Frequently Asked Questions
Can You Put Polyurethane Over the Paint?
Yes, you can put polyurethane over paint. When the paint is fully cured and clean, you can apply water-based and oil-based polyurethane over any paint.
How Many Coats of Polyurethane Are Required Over the Painted Floor?
At least two coats of polyurethane are required over the painted floor. Using water-based polyurethane, you can apply up to four or five coats on surfaces.
Will Polyurethane Finish Stick to All Surfaces?
Yes, polyurethane will stick to most surfaces. But you must prepare the surface by removing small dust particles, wax, or grease and let the surface cure before applying polyurethane.
How Long Is the Paint in Good Condition?
The quality of the paint and the condition of the surface you are painting determine how long the paint will last. Interior paint will last from 5 to 10 years, and exterior paint lasts between 5 to 7 years.
How Much Time Acrylic Paint Takes to Dry?
Acrylic paint will dry in 20 to 30 minutes, and thicker films can take two hours. This will vary according to environmental conditions.
Professional acrylic colors remain usable on the palette for longer than many other acrylics.
What Is Polyurethane Used For?
Polyurethane is one of the most popular materials used in home furnishings such as furniture, bedding, and carpet underlay.
Flexible polyurethane foam makes furniture more durable and comfortable for upholstered furniture.
Can You Paint Over a Clear Coat?
It is possible to paint over a clear coat, but sand off a layer of the clear coat before applying paint. Sand your sanding block and wet your sandpaper before painting over the clear coat.
It is safe to apply two or more layers of color after sanding.
Does the Paint Dry Darker?
The paint does not change its color after drying. During application, paint can look lighter or darker than expected, but good quality paint should dry the color indicated on the lid.
The difference between drying and curing is mentioned in this article. So, you can apply polyurethane over paint as long as it has cured. If the paint takes too long to dry, we have explained how to speed up the process.
It is time to put it to the test with all of this knowledge. There are two types of polyurethane, water-based and oil-based. According to the requirement, you need to decide which polyurethane you should use.