How many layers of polyurethane [everything you need to know] (2023)

The best way to protect your wooden surface is to apply a layer of polyurethane.

Many people like to add a layer of polyurethane to their floors and admire the glossy look. How does it help the soil? Polyurethane is chemical and water resistant and forms a strong protective layer that prevents damage to your wooden floors and furniture.

If you want to apply polyurethane to wooden parts but have no idea how to go about it, you've come to the right place. Look no further for information on polyurethane types, coating, drying and application. We've got you covered in this comprehensive guide.

Let's find out all the aspects related to itpolyurethane, starting with their types.

polyurethane coating

So what is polyurethane and why is it used to coat surfaces? Polyurethane is essentially a type of varnish applied to wood to make it more resilient and preserve its outer layer. Adding a few layers of polyurethane makes the surface water, heat and scratch resistant.

In addition to its protective properties, it looks shiny and smooth, enhancing the beauty of your wooden furniture. If you plan to apply a top coat at home, it makes the most sense to apply a coat of polyurethane. While there are some basic methods you need to learn, it is by far the easiest DIY product to use.

Although we consider polyurethane to be oil based, this is not always the case. There are two types of paint: water-based and oil-based; and their different properties would be something that would be useful to know.

Types of polyurethane coatings

1. Oil based polyurethane

Oil-based polyurethane is the most common type of coating used for furniture. The substance is created by adding polyurethane resin to the paint, which, once cured, gives it its resistant properties. Also, it's been around a lot longer than water-based polyurethane.

Compared to other top coats and varnishes, these have a thicker, oilier consistency. But of course that depends on how many layers you want to add. After application, it leaves an amber hue that adds warmth to lighter woods. These coatings can also be easily cleaned with mineral spirits.

Using this type of polyurethane has its pros and cons. While you get a super strong finish that looks great, they dry slower. As a rule, oil-based paints or varnishes take longer to dry than water-based ones.

And if you add three or more layers, the process can take much longer. They also contain high levels of VOCs, which is why some people today prefer water-based coatings.

2. Water based polyurethane

A more eco-friendly option for your finishes is water-based polyurethane. These are a safer option due to the lower VOC content, which is why people are switching from oil-based to water-based polyurethane.

If you don't want to wait for each coat to dry, water-based polyurethane is better suited to your needs. It levels easily and dries quickly, allowing you to finish your floor or tabletop veneer in days instead of weeks.

Also, you can apply more layers as it dries quickly. While some aspects of this type of polyurethane coating are great, it does have some drawbacks. For example, paints are not as durable as oil-based ones and can be damaged by water.

Likewise, applying polyurethane to water increases the grain of the wood; Therefore, some extra coats are essential to achieve a smooth finish. And since the consistency is quite thin, you'll need more top coats to get a final glossy finish.

How many coats of polyurethane should you apply?

The number of layers applied changes the appearance of the surface and also changes the strength of the wood. But how do you know if one, two, or three layers is ideal? One thing is certain: multiple coats of paint are required to properly protect the underlying wood.

Another rule of thumb is that water-based polyurethane coatings require more coats than oil-based paints. Ultimately, however, the number of coats will be determined by the type of surface, the frequency of surface use and the level of protection required.

1. laminate floor

When deciding on the number of layers of polyurethane for wooden floors, the first thing to consider is the type of finish. As mentioned above, water-based and oil-based paints are very different and require different numbers of coats. But the condition of the wooden floor and the frequency of use must also be taken into account.

When applying water-based polyurethane to floors, at least three light coats are a must. Since the varnish is thin, remember that it will lift the grain off the floor. Three coats should be enough to form a protective layer, but if you want to go even further you can add a fourth coat.

It is recommended to add the layers and polish the uneven parts so that the end result is a smooth and almost reflective floor. If you choose an oil-based polyurethane, you can opt for two coats on your hardwood floor. A new, well maintained surface should not require more than two coats, one to seal and the second to finish.

Hardwood floors that need a new look after many years of use may need a third coat of paint. However, this is not required. For those confused when choosing between water-based and oil-based products, we recommend water-based polyurethane for hardwood floors.

Because water-based paints are much more manageable and can be covered with a new coat of paint if the existing one is damaged. But oil-based varnish can chip, peel and dent if not treated with care and can ruin the final look of your floor.

2. furniture

If you want to provide wooden tables or chairs with a polyurethane coating, there are a few things to consider. You already know that water and oil based paints have different drying times, but there is one more factor to consider.

When an oil-based varnish is applied, it dries to a rich amber color that transforms the furniture, giving it warm tones overall. The water-based varnish has no color of its own and only provides a soft sheen while maintaining the color in the table below.

Here it is your decision to choose based on color difference. Warm tones make wooden tables richer and more beautiful, but the tone may not match your room or home decor. If extra warmth adds interest to your room, an oil-based paint is a great option. However, if you don't want to hide the natural color of the surfaces, a water-based varnish is better.

Applying polyurethane to surfaces

There are several ways to apply a polyurethane top coat. You can brush it on, spray it all over the surface or wipe it on the wood. If the varnish is applied with a brush, there is a chance that the brush strokes will remain on the surface, leaving an uneven appearance. That's why many DIYers prefer spray paint, which is similar to spraying paint on walls.

Spraying is the best method, especially if the surface is not level. And although it's easier that way, you get thin layers of lacquer; therefore 5 or 6 layers are required. When spraying, it's important to work with a steady hand to avoid drips and spills.

If you leave the spray in one spot for too long, the liquid polyurethane will drip and need to be cleaned up immediately. A disadvantage of spray paint is the release of noxious fumes that may not be suitable for those with sensitive skin. If you plan to apply the paint to a flat surface like the floor or a wooden table, using brushes is the best option.

Step-by-step instructions on how to apply polyurethane

Applying polyurethane to surfaces is not a difficult task if you follow the right method. If you're just starting out with the finishing touches, going through this section will help you effortlessly give your floor a beautiful finish.

1. Check your workspace

Before working with polyurethane, you should first check the area and location of its application. Is it a spacious room or a small basement? How well is the room lit and does it have windows for ventilation? These questions are essential for safety reasons and also affect the drying time of the paint.

Because most paints, especially oil-based paints, emit VOCs, good ventilation of the room is required. To improve ventilation, leave windows and doors open for fresh air.

For safety reasons, be sure to wear protective gear when applying the polyurethane. Prepare for clear goggles, gloves and a respirator to protect against VOCs and paint fumes. Finally, make sure the work area is well lit with plenty of sunlight or artificial light. When the light is dim, you can't see small bumps or brush strokes.

2. Prepare the ground/surface

The surface must be well prepared before applying paint. Clean the room/area to remove any obstacles to further spraying or painting. If items or wall decorations are not removed, they may be damaged by spray or volatile vapors. Therefore, remove all wall paintings and lamps from the room.

Now that other items are out of the way, you can focus on the actual work area: the hardwood floor. The first step is to sand the floor well with coarse sandpaper. This must be done at least once on the entire floor. Unfortunately, there is no easy way out of this step and the results will not look good if this step is skipped.

After the rough sanding, lightly sand the surface with finer sandpaper until it feels smooth and even. Clean the dust and wood chips with a regular vacuum cleaner and vacuum the area until all dust residue is removed.

Some people like to scrub the floor with a slightly damp cloth, but this is not recommended as the floor takes time to dry. Also, if there is moisture on the floor and varnish is applied to it, there is a chance that the wood will rot from the inside.

This is especially true for oil-based paints, as they are completely waterproof and hold water without the possibility of drainage and evaporation. However, there is no need to worry when using water-based polyurethane. In fact, wetting the surface beforehand increases the surface grit, which can then be sanded to perfection.

In any case, the floor must be free from dirt and moisture; otherwise the polyurethane may not adhere properly to the wood panel.

3. Seal the top layer of the floor

The first layer of polyurethane can now be applied to the clean wooden floor. The first coat is called the sealer because it acts as a barrier between the wood and subsequent coats of varnish. This layer is always thinner than the others and can be achieved by diluting the paint product already purchased.

Wood is generally porous and applying thick polyurethane directly can cause blistering. A seal closes the pores of the wood and prevents blistering. There are special sealers on the market that are made for self-application; however, they are expensive.

And the same task can be accomplished by creating your own layer of sealant, so you don't have to buy additional sealant. So how do you make a polyurethane sealant? It's easy to mix two parts of an oil-based product with one part of spirits. Mix well to get a liquid consistency that flows and spreads easily.

If using water-based polyurethane, use the same ratio but replace the alcohol with plain water. Now that the mixture is ready, use a large brush to apply the sealer to the floor in long strokes. Try to cover the entire floor without dripping.

A good tool for this is a natural bristle brush, which leaves fewer marks and gives a smoother finish than synthetic brushes. In some cases the sealer will not adhere to the wood because the stain may be oil based.

An oil based sealer shouldn't have this problem, but a water based one requires extra preparation. To roughen the floor, you can use steel wool instead of sandpaper to help the paint adhere better.

4. Apply the first layer

Technically, sealer is the first coat applied to the floor, but the viscous first coat is called a primer. After applying the sealer, wait 24 hours before adding this polyurethane primer. After approximately 24 hours the seal should be completely dry if the room has access to fresh air.

Then you can go ahead and apply the first layer. Remember not to create layers that are too thin with this first layer, as this will create gaps in random places. When spraying in this layer, the layers can be a little thin, so take your time to cover each section well enough.

And if you prefer to use a brush, try connecting and overlapping the strokes. This avoids scratchy lines after lifting the brush. Also try to smooth out drips and spills as you walk across the floor rather than waiting to the end to fix them.

Depending on the polyurethane base, you will need to follow different steps to complete the remaining steps.

A. Procedure for applying oil-based polyurethane

The best application tools for oil-based polyurethane are a foam roller or brush, natural-bristle brush, or soft-bristle brush. Avoid rough or synthetic brushes, which often leave streaks and don't allow the polyurethane to sit evenly.

First, dip the foam roller or brush into the polyurethane can or can and pull it out, dripping the excess into the can. Do not rub the side of the can with the brush to remove any bubbles or excess product. This creates gaps in the wooden floor when applied.

Instead, tap the center of the can several times with the brush. Keep in mind that oil-based polyurethane coats are usually thicker and trying to force them into thinner coats won't give you the smooth finish you're looking for.

The number of coats required will vary depending on the intended use and the type of flooring. But two- or three-stage applications are the norm. Sanding is another step that cannot be missed when applying oil-based polyurethane.

B. Method of applying water-based polyurethane

The first thing to know is that this type of varnish is much thinner, so there is a greater chance of dripping and spilling. The best tool for water-based polyurethane would be a foam roller, but you can also use a soft or cloth brush. The application method is slightly different from oil-based varnish.

Be sure to apply thin coats of this varnish as thick coats of moisture containing products can enhance the grain of the wood. Sanding the first coat is essential with oil-based paints, but not necessary when processing water-based polyurethane. For best results, three coats of this clear coat should be sufficient on less stressed areas of the floor.

Up to four coats are required if the floor is subjected to constant stress. Because the drying time is much faster, the entire project will take less time compared to oil-based polyurethane.

5. Sand the first layer

After applying the sealer and the first coat, the parquet floor must be sanded to even out any imperfections left by the first coat. However, the sanding process can only be started 24 hours after applying the varnish. The fur should be dry at this point.

Start sanding with fine sandpaper using the wet sanding technique until the surface is smooth again. To prevent the paint from peeling off, dip the sandpaper in water frequently while sanding. Finally, wipe the entire surface with a damp cloth, removing dust and chips. The surface must be completely dry before applying the next layer of polyurethane.

6. Add the remaining layers

In general, you can apply more coats of polyurethane than recommended if you feel your flooring or furniture calls for it. However, remember not to apply the next coat until the previous one has completely dried. Also, don't skip sanding between coats, especially if you're using an oil-based clear coat.

Only when the layers look noticeably smoother and more even can you avoid this step. Finally, the last layer should be polished, not sanded. This last step gives the surface the shine characteristic of polyurethane coatings.

7. Polish the last layer

By sanding the coatings, they adhere to the next layer, smoothing and leveling it. But the last layer needs polishing to give it a shiny, almost slippery look. After the previous painting, the surface must remain intact for at least 48 hours.

Use a good quality polish suitable for polyurethane application. It is best to choose a polish with fine particles that will remove sandpaper scratches. Dampen a soft cloth, apply some polishing cream and rub the floor in a circular motion.

This should give the entire surface a smooth, shiny look. After the floor dries, wipe with a dry cloth to complete the process. If the surface looks cloudy, repeat the process until it becomes clear and mirror-smooth.

Tips for applying polyurethane to a table

While most hardwood floor finishing instructions remain the same, there are a few other things worth mentioning. First, try to work indoors as much as possible. Unlike finishing floors, tables can be moved around the house, and some people enjoy gardening.

The problem with exterior painting, however, is that you are increasingly exposing yourself to dust, smoke, and other pollutants. Even small bugs can cling to wet paintwork and ruin the finish. For this reason, it is best to repair furniture indoors in a ventilated place like a garage.

Best results are obtained on a perfectly flat surface. Therefore, if the table is uneven, you can sand it with fine sandpaper. The flatter the surface, the better the flatness and the layers glide easily without dripping.

How long should you stay away from the apartments?

Freshly painted furniture can be stored in the garage or in an empty room where nobody can touch it. But what about the floors? How long does it take before you can walk on it? To understand the required time, remember that after drying the varnish takes a long time to harden. Only then can we say that the whole process is complete.

However, you may have heard that wood can take weeks or even a month to fully cure. The question is, when is it safe to walk across the floor and put up heavy furniture without ruining the paintwork? Let's figure out the two steps: drying and curing.

1. dry

Hardwood floors typically take at least 24 hours to dry. At this point the top layer has hardened but the inner layers are still being processed. So this floor cannot be used for walking and standing and certainly not for dragging furniture across the floor.

It is advisable to ventilate the room so that the windows and the door remain open. But if you have small children or pets who can enter this room suddenly, it is better to lock the door. In fact, you shouldn't walk on hardwood floors for at least 48 hours after painting.

After 48 hours, you can walk the floor in a soft pair of socks, but avoid moving furniture for now. Walking with shoes or boots, or even barefoot, the pressure can leave marks that, once formed, cannot be removed.

2. curing

Curing is the process by which polyurethane resin molecules form irreversible bonds, becoming extremely hard and resistant to change. Curing takes much longer than drying; Until then, the joints are not strong enough for everyday use.

On average, a water-based polyurethane paint will take two weeks to cure, while an oil-based one will take 3-4 weeks for the same number of coats. Walking on the floor before healing is complete is a big no-go. It's best to lock the room or avoid it for the entire healing time.

As mentioned earlier, walking around in soft socks on varnished floors should be bearable for a week. But walking in boots should not be allowed until after the healing time. The same applies to moving cabinets, tables and all other heavy furniture.

Working with oil based polyurethane is a little tricky. Not only does it take twice as long to cure, but it also dries in two steps instead of just one like water-based. In the first step, the light, water-soluble diluents evaporate into the air, leaving a tack-free surface.

Over the next two weeks, the oils in the paint react with the oxygen in the air, helping it to harden over time. Once all the oil molecules have reacted, a hard protective layer forms, which is the final stage of the healing process. Note that environmental factors play a role in the speed of curing time.

If the room is damp and wet, it will take much longer for the paint to dry and harden. An easy way to tell when curing is complete is when the floor stops smelling. As long as you can smell the smoke, the healing process is not complete.

FAQ about how many layers of polyurethane

last words

Here we come to the end of our complete guide to polyurethane coatings. When using polyurethane, it is important to remember that even two layers protect the wood from water, dust and bugs. However, more than two coats are required to achieve a beautiful specular shine, be it water-based or oil-based.

If you want to prevent wood floors or furniture from deteriorating due to moisture, oil-based polyurethane is your best bet. But if you need a quick makeover for old wood, water-based polyurethane should do the trick.

We hope this guide answers your questions about polyurethane coatings and their application. Ask more questions in the comments below.

Until next time, bye!

Related Articles

The 9 best brushes for polyurethane

The 11 Best Polyurethane Protective Coatings

Water based versus oil based polyurethane floor coating today

How long does it take for polyurethane to dry?

How to paint the surface next to the carpet

9 Best Polyurethane Shell | Reviews + Buying Guide