Wood Whiz

How Many Coats of Polyurethane – Everything about Applying Poly

How many coats of Polyurethane

How Many Coats of Polyurethane - Everything about Applying Poly

Polyurethane is a type of varnish/paint that can be used on different surfaces. It consists of two types of ingredients: polyols and diisocyanates. Polyol or polyether-based ones are more flexible and resistant to water while the alkyd-based ones offer better wear properties such as scratch resistance.. This article will discuss everything you need to know about applying polyurethane, including its composition, how much you should use, and how long it lasts before needing to be reapplied.

About Oil-based and Water-based Polyurethane

Oil-based Polyurethane: The alkyd-based polyurethane is the most common type. It offers a wide range of qualities and properties, with higher quality paints being more flexible but less resistant to water. They dry up more slowly compared to water-based polyurethane so the wait time between the coats is longer.

Water-based Polyurethane: Water-based Polyurethane has the property of drying faster than solvent-based and produces less odor. It is also thinner and more liquid, so it needs multiple coats to completely cover the desired area.

How much and how many coats of polyurethane should I apply?

The number of coats and quality will vary depending on the application. For example, when applied as wall paint or with wood finishing products like varnish, more layers are needed for better durability than with a floor care product like polyurethane.

Oil-based polyurethane will usually require less coats than water-based polyurethane due to it having a higher level of resistance to abrasion. Nevertheless, the number and quality will also depend on how much polyurethane you apply for each coat as well; this can be determined by your needs which may range from durability or maintenance depending on what application it’s being used with ( flooring vs furniture).

Water-based polyurethane is much thinner than oil-based. The number of coats you may need vary between products, but usually four to five coats are best.

After about 24 hours of drying time, sand the surface until it is completely smooth. Unless the surface is completely dry, it’s best not to apply a fresh coat of polyurethane. Wait for 12 hours before doing so.

Usually, with oil based polyurethane you should apply two coats at least because one layer does not provide enough protection against abrasion.

How to Apply Polyurethane: Step by Step

  • Prepping the Surface

    Prepare the surface with a tack cloth or other dusting agent, sand in any rough areas and wipe clean (repeat this step if necessary). Use sand paper or a sanding block to remove any scratches or imperfections. Smoothing the surface before applying polyurethane is extremely important.

  • Applying the Sealant to the wood surface

    The first step to applying polyurethane is blocking-in coats of sealant, which are applied very thin. This is important as wood is porous and needs to be sealed with multiple coats of clear sealant (if you are sealing your wood) not soak into it. Thinning can help to create a more even finish.

  • Repeat

    Repeat the process until you reach the desired texture. Usually 2-3 coats are enough for a smooth finish.This will also depend on the wood, as some types of woods are more absorbent than others and need additional coats to get an even texture without any drips or bubbles. The final coat of polyurethane should be polished with a synthetic polisher to remove any excess. This will result in an attractive finish that is slick and shiny, perfect for maintaining wooden objects or floors.

Do you sand the Final Coat of Polyurethane?

Yes. You want to sand the final coat of polyurethane in order for it not to have any imperfections and that can be seen by others on your piece, but only lightly,. This is just a quick pass with very fine grit paper or 600-grit wet/dry abrasive before rebrushing one last time over parts of the surface that need it.

Tools used to apply polyurethane

When you apply polyurethane varnish, it can be done in a number of ways. The most common type is brushing it on and then wiping the excess.It gives you an even coat that will last longer, make sure that you brush along the grain of the wood, then wipe it off. It is recommended to do this in sections so that you can get a more even coat and not end up with raised edges on your final product. It is important to dip the brush straight into the can when applying polyurethane. Doing this will prevent bubbles from forming as well as adding excess material. To remove any remaining paste, rather tap the bristles of the brush in a downward motion onto an open tin lid.

Spraying is best for large areas or for projects that will be difficult to brush. Although it is easy to apply, the coat is very thin so it won't provide much protection. Recoating multiple times with polyurethane varnish will give you a stronger finish.

If you want a smooth finish, use an electric buffing machine with foam disks, this will make it easier for your hand and arm muscles not be as strained when applying polyurethane over large surfaces like walls!

How to prevent air bubbles from forming on polyurethane

Polyurethane is a liquid paint that has an elastic quality to it. If you see bubbles forming in the finish, that means the sealant is not sticking.There are various ways you can remove them; you can use rubbing alcohol and make a mixture of one part water and two parts rubbing alcohol, or mix vinegar with half-strength hydrogen peroxide.

Another method is to sand down the bubbles with a sanding block. However you need to wait until the layer is completely dry.Thinning the polyurethane is a final way of eliminating bubbles. This is done by adding more mineral spirits or turpentine to the polyurethane.

bubbles in polyurethane

How to remove the brush marks on a polyurethane finish?

Get rid of brush marks

Many people are looking for ways to remove brush marks from a polyurethane finish. This is actually fairly easy, and can be done by simply sanding down the entire surface with fine-grit paper until any rough or textured surfaces have been polished away. Once you’re done cleaning the surface, you can apply another coat of polyurethane , just make sure to thin it out with a solvent so that the final coat goes on smoothly.

The result is usually completely clear of any rough patches or brush marks that may have been caused by brushing on too much product at once – in other words they are no longer visible after this process has taken place! It’s important not only for appearance , but also for the final durability of your polyurethane finish.

Why is taking too long to dry my Polyurethane?

This is typically caused by high humidity. The best way to ensure that the polyurethane dries properly, or at least faster than if you were in an area of low-humidity such as a desert for example) is taping off all windows and doors so air cannot escape your space). Then use fans to circulate air.

Recommended Temperature: Polyurethane needs to be applied in most cases at a temperature between 50 and 70 degrees Fahrenheit or even higher.This will allow the polyurethane to dry twice as fast than if temperatures were not regulated at all, or above 100F causing bubbles and damage from too much heat). You can also boost circulation in the workspace and keeping it at a low humidity level.


When creating a project from scratch, using the correct type of polyurethane is key and will help you avoid costly mistakes when it comes to application and consistency in drying time.If you are working with a brush, make sure its a nice, stiff bristle brush and you have a good amount of polyurethane in the can.


Thinning the polyurethane can help with application and will not change the quality. A thinner mixture also helps for those who are using a roller because it can be absorbed better into surfaces, without leaving brush marks behind or streaky lines on horizontal areas of walls like ceilings when applying horizontally as well.


Lastly, if you are going to apply polyurethane, use at least two coats for a good finish. If you need that third coat, then your surfaces get quite a bit of traffic and you’ll probably want to put the last one on thicker.


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