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How to Apply Polyurethane to Wood

A man applies polyurethane to a wood table or desk using a small brush.

Polyurethane is a type of varnish commonly used to protect wood finishes. At home on desks, tables and work spaces like kitchen countertops, polyurethane is designed to be durable enough to withstand years of use even on high-touch surfaces.

Learning how to apply polyurethane is a useful skill for any DIY enthusiast. Use this guide to learn more about choosing the right type of polyurethane for your project as well as how to apply it like a pro.

Skill Level: Beginner
Time:
  1. Step 1 Choose Between Oil-based Vs Water-based Polyurethane

    A can of clear satin polyurethane is stirred before use.

    When working with polyurethane, you’ll need to choose between oil-based and water-based polyurethane. They both have benefits and drawbacks, so consider your project and specific needs carefully before choosing.

    Oil-Based Polyurethane

    Oil-based polyurethane generally forms a hard, durable finish in just a few simple coats. However, these coats dry slowly compared to water-based polyurethane. Oil-based polyurethane typically gives your wood a warm amber hue as well. Oil-based polyurethane is also higher in VOC’s than water-based.

    Water-Based Polyurethane

    Water-based polyurethane requires more coats, but each coat dries quickly. Low VOC content makes it easier to find and potentially safer to work with as well. However, you’ll still need proper ventilation when working with water-based polyurethane.

    Water-based polyurethane typically dries clear, helping you retain the natural look of the wood you’re working with.

  2. Step 2 Pick the Best Polyurethane Finish for Your Needs

    Side-by-side photos show polyurethane being brushed onto a wood surface.

    Polyurethane comes in three finish types: satin, semi-gloss and gloss. Here’s what you should know about each:

    • Satin. Natural appearance, minimal shine. Ideal for wood projects that should have a natural finish. Satin polyurethane still provides a layer of protection that will benefit any wood piece.
    • Semi-gloss. Higher shine adds some gloss to your finished product. Semi-gloss polyurethane is a good middle-ground choice. It’s also easy to clean.
    • Gloss or high-gloss polyurethane. Adds a high level of shine to your finished project that may be ideal in some contemporary environments. Glossy finishes may show nicks and damage over time.
  3. Step 3 Prep the Wood

    A man sands a wood table by hand to prepare it for staining.

    Before you can apply a coat of your chosen polyurethane, you’ll first need to prep the wood. First, remove any old paint or varnish. Stripping products are a great way to start this process. Sand the wood using 120-grit sandpaper if it has been refinished. New wood fares well with 80-grit sandpaper. You can use a hand sanding block or an orbital sander.

    Wipe the wood down to remove dust and debris and finish sanding with fine 180-grit or 200-grit sandpaper. Make sure the surface of your wood is level before moving on.

  4. Step 4 Clean Thoroughly

    A gloved hand cleans a wood tabletop.

    Before you can apply polyurethane you’ll want to clean your wood thoroughly. Using a hand-vacuum or hand broom can help clear large pieces of debris. A dampened microfibre cloth, followed by a dry microfibre cloth, will help remove any wood dust that may still be present.

  5. Step 5 Apply the First Coat

    A man applies polyurethane to wood with an orange paintbrush.

    With your wood surface thoroughly cleaned you can now apply the first coat of polyurethane. Using a clean brush, apply polyurethane in even strokes along the length of your wood piece. Start sparingly, as brush-on polyurethane tends to cover a lot of surface area.

    For wipe-on polyurethane, dip your cloth or sponge into the polyurethane and wipe it onto the wood, working along the length of your wood piece. Aim to coat the wood evenly using a pushing or pulling motion as you work.

    With spray-on polyurethane, paying careful attention to your distance from your wood work surface, spray it along the length of your wood piece. Aim for a smooth and even wrist motion. You should test spray-on polyurethane on a spare piece of wood before using it, as drips are a common problem if you haven’t refined your technique.

    Tip:

    Spray-on polyurethane typically works best from a distance of eight to 12-inches. Follow the manufacturer’s directions if you’re unsure about the product you’re working with.

  6. Step 6 Sand and Repeat as Needed

    A woman in work gloves applies polyurethane to a dark wood table.

    You’ve applied your first coat of polyurethane, but you’re not quite done with your project yet. Wait 24 hours after applying your first coat of polyurethane. Oil-based polyurethane may take a little longer to dry under certain conditions.

    Sand your work surface with 180-grit, 200-grit or 220-grit sandpaper to remove drips, spills and uneven spots. You can also use a utility knife to carefully shave off any large spots or spills you can’t easily sand away.

    Add an additional two to three layers of polyurethane, depending on your method. Brush-on and wipe-on polyurethane typically requires two to four total coats. Spray-on polyurethane may require an additional coat for even coverage.

  7. Step 7 Tips for Working with Polyurethane

    A man in a respirator uses brush-on polyurethane to finish light natural wood.

    Tips for applying polyurethane:

    • Take extra time sanding and cleaning your wood before you begin. Applying polyurethane will be much easier and you’ll get the consistent results you want with less work on your part.
    • Pick the right brush for the job. Natural fibre brushes are a great pick for oil-based polyurethane. Look for synthetic polyester or nylon brushes for water-based polyurethane.
    • Pour a small amount of the polyurethane you’re using into a clean container and seal your supply. That will keep dust and debris out of your polyurethane as you work.
    • Go with the grain. Brush or wipe with the grain to get the even look you desire.
    • Skip the steel wool. You may have seen steel wool used for sanding before, but it’s not ideal if you’re coating wood with polyurethane. Even tiny bits embedded in the surface of your wood will rust and show themselves over time.

    Learning how to apply polyurethane to wood is something you can do even if you’re a DIY beginner. Shop The Home Depot today or visit us in person to find the right polyurethane and all of the supplies you’ll need for your project.

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