How To Spray Polyurethane

Whether you’ve recently moved home, or you’ve decided to renovate your existing place, it only makes sense that you’ll be considering spraying polyurethane in order to give your flooring or chosen surface a shiny, glossy finish.

However, despite its attractive appeal, polyurethane is well-known for being very tricky to use, with many first-timers finding themselves running into a whole host of problems including cloudiness, a white-cast, bumps, and even bubbles. So, what can you do?

The trick is in the technique, which is where we come in. In this guide, we’re going to be talking you through how to correctly apply polyurethane by using a paint sprayer, in order to ensure your flooring finish is a success.

Read on!

How to Spray Polyurethane

What is Polyurethane?

Polyurethane is a type of resin coating that is used as a finishing varnish most commonly on floors, cabinets, drawers, and other types of woodwork surfaces.

Polyurethane is a very popular type of finishing varnish because it is glossy and transparent, meaning that you will still be able to see the color of the surface underneath.

Polyurethane is also desirable because it is able to prevent mildew and fungus growth, as well as being able to resist any abrasions or other kinds of damage.

How To Prepare The Spray Gun and Paint:

Polyurethane varnish is traditionally applied by using a paintbrush to carefully paint a thin layer on top of the surface.

However, this method is quite problematic (especially for beginners) as it is very easy to accidentally overcoat, leading the finish to become bumpy, too shiny, or even cloudy in appearance.

In contrast, spray paint will allow you to maintain the thin consistency of the coat, ensuring a flawless, glossy finish. However, in order to achieve the best results, you’ll need to carry out a few preparatory steps first. Let’s take a look:

1. Prepare the Spray Paint Gun:

The first thing to do is make sure that your sprayer features the correct tip. Like we mentioned above, polyurethane needs to be applied very thinly, so a tip that will be able to spray between 1 to 6 inches is ideal.

Your spray paint gun should have come with a variety of different tip selections upon purchase, however, if you don’t have the right tip size, then there are a variety of spray paint tips available to buy online at affordable prices.

After you have attached the correct tip to the end of your spray paint gun, the next thing to do is make sure that you have adjusted the volume control knob.

This is one of the most important parts to get right, as the volume control will allow you to tailor the spray paint gun to spray a thin coat of polyurethane.

This might be hard to get right at first, especially if you’ve never worked with polyurethane before, so we recommend taking a small amount and practicing spraying across a surface you don’t mind ruining, all the while adjusting the volume control until you’re happy with the amount of spray being released.

2. Prepare the Surface:

The next step is to prepare the woodwork or surface that you intend on applying the polyurethane.

In order to ensure that your finish is not spoiled by bubbles or bumps, it’s important to first ensure that there is no dust, dirt, and debris, which you can achieve by cleaning it with a cloth.

You could even choose to sand down certain areas of the surface that aren’t completely flat, though we don’t recommend trying this if you’re not confident.

3. Prepare the Polyurethane Mixture:

So, after you have prepared both your spray gun and surface, the next thing to do is to properly prepare the polyurethane paint mix. First off, you’ll need to create a priming mixture of polyurethane and paint thinner, and add them both into the spray paint container.

This will help to create a smooth and strong foundation for the rest of the pure polyurethane to be applied on top of.

Spray Painting Polyurethane: Step-by-Step Instructions

Now it’s time to spray the polyurethane! As we mentioned above, though spraying polyurethane is a lot more effective than the traditional way of using a brush, it does require a specific type of technique. Follow the instructions below, and you won’t go wrong:

1. Get Set Up

First things first, you’re going to need to get everything ready to use. Switch the spray paint gun on with the priming mixture, and position it so that it is around 10 inches away from the surface.

By doing this, the coats you apply will go on smooth and shiny, free from any of those pesky bumps or imperfections.

2. Spray the First Layer

Now you’ll be ready to begin spraying. Before you start, you might find it helpful to first try this simple exercise:

Holding the spray paint gun as if you were to begin using it, practice moving your arm in a long, flowing motion back and forth a few times.

This will help you get a feel for the spray paint gun, and help to ensure that when you begin, the paint will go onto the surface evenly and look uniform.

When you’re ready, you can then begin spraying the polyurethane. As soon as you have completed the first layer, stop and pour some pure polyurethane into the spray paint gun’s container before you begin spraying your next coat, as this will help to maximize bonding.

3. Begin the Layering Process

After you have completed the first layer, it will now be time to continue with the layering process. As you spray each layer, remember to spray the surface in a long motion to maintain a uniform appearance.

In order to ensure that no inconsistencies are made while layering, we suggest beginning to spray just before you spray onto the surface, and then continue to spray until after you have sprayed past the end of the surface. Keep doing this until you have sprayed the final layer.

4. Allow To Dry

After you have completed the final layer and you are happy with the finish, it will now be time to allow the polyurethane paint to dry.

For best results, we recommend allowing the painted surface around 24-48 hours to dry, although this can vary depending on what brand of paint you are using, so we recommend checking the manufacturer’s information for the optimal drying time.

Additional Advice:

While layering, it’s important to allow the polyurethane to dry until it is no longer tacky, and then sand it down. Polyurethane is unable to adhere to itself unless the layer before it is rough and contains bumps, as this will give the next layer something to be able to bond to.

While sanding, it’s important to remember that you don’t need to remove the entirety of the dry layer, but simply rough it up so that the following layer will be able to properly stick to it.

In addition to this, we also recommend that you dust down each layer before applying the next. If you don’t, then there is a strong chance that the next layer will trap all of the dust, leading to an imperfect, cloudy finish.

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