Can You Apply Spar Urethane On Acacia Wood?

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Spar urethane can be an effective choice for protecting acacia wood furniture. Its water-resistant properties make it suitable for outdoor applications, such as patio furniture, where acacia wood is commonly used.

Properly applying spar urethane can help preserve the natural beauty and durability of acacia wood in various settings. So, in this guide, I will clarify if you can apply spar urethane on acacia furniture and a few must-read tips!

Can Spar Urethane Be Used On Acacia Wood?

While most people in the wood furniture industry have heard of polyurethane in passing, only a few and usually more experienced woodworkers and wood crafters encountered spar urethane.

Spar urethane is a flexible, durable self-leveling sealer and finishing designed to withstand harsh environmental elements. It is a spar varnish with urethane plastic included as a resin. 

It’s typically a go-to material and tool for any exterior wood piece that requires a clear finish. This sealer can protect a wide range of softwoods, hardwoods, and other wood-based materials.

applying spar urethane to wood

With this in mind, spar urethane is a good option for acacia wood use. You may use spar urethane on this wood type without issue or problem. The sealer can protect acacia wood from water and UV light, extreme weather conditions, moisture, and other elements.

The spar urethane sealer can coat the acacia wood with a robust protective layer — all while enhancing its appearance and physical features! You can easily find and purchase two primary spar urethane on the market that would go well with acacia wood:

  1. Water-based spar urethane
  2. Oil-based spar urethane

To help you better understand the two types of spar urethane, here is a detailed comparison you can check out.

Water-Based Spar Urethane

Oil-Based Spar Urethane

Creates thinner layers and coats

Creates thicker layers and coats

Easy to clean up using water

It proved tricky to clean and would typically require mineral spirits to remove

A more flexible type of finish

Limited in terms of flexibility

It tends to dry and cure much faster 

It typically takes a longer time to dry and cure

It offers a transparent and clear finish

Leaves behind an amber-yellowish tone 

Typically on the pricier side

More affordable and budget-friendly

It does not darken over time

It tends to darken slightly

Thin using denatured alcohol before applying

Thin using mineral spirits before applying

Prone to scratches

Prone to dents 

Moderately hard and stable type of finish

More hard and stable type of finish


What Are the Advantages of Applying Spar Urethane Over Acacia Wood?

acacia grain
  1. The sealer can make the wood waterproof
  2. It is easy to maintain and apply.
  3. Spar urethane can help prevent the wood from being susceptible to cracking and warping.
  4. It can make the wood more durable and robust.
  5. Applying the sealer can help improve the wood’s sheen and shine.
  6. Spar urethane can help the wood become more tolerant to extreme weather or climate conditions like snow, rain, moisture, and abrupt temperature changes. 
  7. The sealer is also non-toxic and, therefore, safe for furniture and items that make contact with food.
  8. It can help in hiding scratches and dents.
  9. It also can help protect the wood from bug attacks and insect infestations [1].
  10. Spar urethane can make the wood last longer than anticipated or expected.

Those are the most common advantages of applying spar urethane on acacia wood. There is a relatively good chance that more are left unmentioned or undiscovered!

One thing is for sure, however — the list of benefits above should be enough to make spar urethane more appealing to woodworkers and carpenters!

Other Uses of Spar Urethane

For acacia, you can use spar urethane on any wood piece of furniture without much trouble or issue! Apply it properly and give it enough time to dry and cure!

minwax spar urethane

Tools and Materials Are Required to Apply Spar Urethane Over Acacia Wood

To apply Spar Urethane on your acacia wood furniture, you’ll need some essential tools and materials to get started. Depending on your preferred application method, you can choose from a variety of applicators. 

These tools will help you achieve a smooth and protective finish on your acacia wood pieces. The most popular applicators for applying spar urethane are foam brushes, sprayers, rollers, and bristle brushes. 

As for the spar urethane itself, you have two options to choose from — water-based and oil-based. You can freely choose mainly based on your needs and preference.

A spare or extra acacia wood scrap is an optional tool to have on hand! You may use it to test the spar urethane on the acacia before applying it to the main piece. Doing so can help you guess the expected result. You can check and see if the finishing look suits your taste. 

Also, you can use the scrap to practice to help minimize and reduce the mistakes you could have made in the application process!

Rust-Oleum 9341 Ultimate Spar Urethane Oil Based, Quart, Satin

Spar Urethane Application on Acacia Wood: 8 Steps

Tools and Materials You’ll Need

Step #1: Prepare and clean the surface of the Acacia wood.

Before you jump straight to working on the wood, you must prepare it first. Like applying spar urethane on a painted wood surface, taking the wood furniture to a spacious and well-ventilated spot or area would be best.

In doing so, you can ensure the sealer dries and cures much faster than usual. Also, a well-ventilated area and spot mean you won’t suffocate from the relatively strong smell of spar urethane. 

Although the finish generally dries faster than many other products, you can expedite the drying process by applying it in a well-ventilated area with good air circulation.

This not only accelerates the drying time but also provides better lighting, allowing you to observe the wood piece more clearly during the finishing process.

There is also the fact that spar urethane can release harsh chemicals and fumes, similar to other finishes. Being exposed to that can lead to breathing issues and problems like asthma. You are also not safe from eye and skin irritation.

preparing wood for spar urethane

An open area or well-ventilated spot can ensure the chemicals won’t settle in your working space. If you’re working inside or indoors, open the doors and windows to invite more air in.

After preparing the working area, it’s time to clean the surface of the acacia! You can use clean rags to remove the dirt, grease, and dust on the wood. 

Use TSP or trisodium phosphate for any stubborn dirt that refuses to budge. Just saturate the rag with TSP and use it to wipe the wood’s surface. Do so until the wood is thoroughly clean and dirt-free.

Spar urethane can trap any leftover dust that can ruin the acacia’s appearance. Any dust and dirt can also reduce the overall performance of the finish.

Step #2: Sand the surface of the Acacia wood.

Sanding the wood helps smooth the surface, removing bumps and imperfections that could affect the application process.

sanding acacia wood

Also, sanding can help open up the porous texture and structure of the wood, making it easy to absorb the finish without the risk of forming any splotches or flaws on the surface. 

Use 120-grit sandpaper to start. Sand the entire wood surface and ensure that you follow the wood grain’s direction. Don’t apply hard pressure as you sand. Also, cover every spot and crevice.

The sanding process can help give enough adhesion between the acacia and spar urethane. Sanding can also help properly even out the natural color of the wood.

After sanding the surface, clean off the sawdust with a clean rag. Ensure there is no leftover sawdust in the wood before you start the application.

Step #3: Thin the Spar Urethane before applying.

Typically, spar urethane creates thick coats and layers that would take time to dry and cure. You can, however, thin it out using either mineral spirits or denatured alcohol.

thinning spar urethane

Thinning the spar urethane can make the application much easier on your part and make the drying and curing time much shorter than necessary.

For those using water-based spar urethane, you will need denatured alcohol to thin it out. As for oil-based ones, mineral spirits are the ideal choice. Here is how to thin the spar urethane:

Note that while the thinning process is only optional, it is recommended. Not only does doing so ensure a shorter drying time, but thinning can also help make an even finish.

Remember that thinning is only required if you use the wiping or brushing application method. Spraying does not require thinning since the tool is already pre-set to release a thin layer or coat through the nozzle. 

brushing wood with spar urethane

Step #4: Apply the first coat of Spar Urethane.

You can consider four different application methods for spar urethane:

  1. Rolling
  2. Wiping
  3. Using a foam brush
  4. Using a bristle brush

When applying spar urethane to your acacia wood furniture, choose an applicator that suits your preference and apply a thin finish layer. 

Make sure to follow the direction of the wood grain, applying even and consistent pressure for a smooth and professional finish. This technique will help enhance the beauty and durability of your acacia wood pieces.

As you apply the finish, be careful not to leave any blotches or imperfections behind. Use light, long, and even strokes when using a brush as an applicator. Also, avoid leaving any brush marks. That will indeed show later on. 

It won’t take long for the wood to absorb a good enough amount of the spar urethane. Once absorbed, the spar urethane will saturate the wood fibers, making them flexible and durable to stand against cracking and warping.

If you want to avoid making mistakes, practice on the scrap wood. Apply the finish to it and see how it behaves on the wood. Let the coat sit for about 30 minutes before wiping off any excess finish using a clean rag to even out the surface.

applying spar urethane on wood

Here are a few extra reminders to avoid making further mistakes while applying the spar urethane on acacia wood:

Step #5: Allow the first coat to dry thoroughly.

Allow the first and initial coat to dry for about 24 hours. Mainly, the finish dries within the first 4-6 hours, but that number can vary depending on the weather and humidity conditions. 

Check the surface upon reaching hour-6 by touching it to see if the coat is still wet or cold. If it’s not tacky or cold anymore, that’s a good indicator that the coat is thoroughly dry. 

Depending on the coat’s thickness, the drying time can last about 24 hours. The thicker the layer and coating, the longer it will take. Also, water-based spar urethane typically dries faster than its oil-based counterpart.

allowing the first coat to dry

Remember to apply the second coat if the initial one is completely dry. Not doing so can result in a tacky surface and a not-so-good final appearance.

Step #6: Gently sand the surface of the first coat.

Once the first coat is dried completely, lightly and gently sand the surface again using 320-grit sandpaper along the wood grain’s direction. 

Sanding between spar urethane coats ensures that the next coat sticks properly on the surface. The sanding process will serve as a good adhesion. 

While sanding, ensure no sanding marks are left, and you don’t miss a spot. Once done, clean off the surface and remove the sawdust using a clean rag.

Step #7: Apply additional coats of Spar Urethane as needed.

Apply another spar urethane coat and follow the wood grain’s direction. Be careful not to miss any spot or area.

door painted with Minwax Helmsman Indoor-Outdoor Spar Urethane

Follow the steps you did during the first application. Apply 3-5 spar urethane coats on the acacia wood to ensure a nice, even surface with an enhanced appearance and sheen.

Apply thin layers and coats for fast drying time. Please wait at least 24 hours for each coat to dry completely before you sand it and apply the next round of coat.

Step #8: Allow each coat to dry and cure properly.

After applying the final spar urethane coat on the surface, let it dry for about 24 hours and cure for at least 2-3 days. 

Properly giving the wood sufficient time to dry and cure will guarantee a protective coat, better sheen, and improved final appearance. It will also ensure that the wood piece is safe to use. 

Leave the wood to cure entirely and avoid handling it during that time. Please put it in a dust-free area and environment. Note that the temperature and humidity can affect the drying and curing time. With low humidity, the coats will dry and cure faster.

allowing to dry the wood coat

Of course, the opposite can be said and applied when the humidity is high.

The maximum curing time should be two weeks. If the wood still feels tacky or wet after 14 days, there is a high chance you did something wrong that messed up the application or drying process. In that situation, start over.

What Is the Durability of Spar Urethane When Applied for Outdoor Use?

The original purpose of the spar urethane finish is to protect the spars or wooden poles of a sailing ship while traveling over water. It protects it from harsh climates and elements.

Applying spar urethane on outdoor acacia wood furniture means it can protect against extreme weather conditions like snow, rain, and temperature fluctuations. It can also help withstand high humidity.

That particular trait and benefit of spar urethane make it an ideal choice for protecting outdoor and exterior acacia wood projects and furniture. The finish is also flexible, adjusting to the wood when it contracts or expands.

Spar urethane also has additives that help prevent the wood from acquiring sun damage. It can help prevent fading caused by harmful UV rays.

spar urethane

What Sealant Is Recommended to Use on Acacia Wood?

Acacia goes well with most kinds of sealants in the market. It’s not picky and is typically not sensitive to most properties or ingredients.

To choose the ideal sealer for your acacia wood furniture, you must find the one that suits your preference and needs the best. Some sealants can provide better protection from harsh environmental elements and climates.

There are also a few with better waterproofing and appearance-enhancing abilities. The list of options and choices is a long one. To help, here are a few sealants that work best on acacia wood:

Apply only thin coats of the sealant on the wood to ensure a clean and even finish. Also, make it a habit to properly maintain and clean the acacia wood furniture and wood piece if used regularly.

polyurethane oil based

Doing so can help make the wood piece last much longer than it should. Aside from the mentioned sealants, there are others in the market you can try out.

What Is the Recommended Method for Sealing Acacia Wood?

The best way to seal acacia wood is by using a waterproof sealer containing UV blockers to protect it from most weather elements. Choosing a good sealer ensures that the wood will have increased durability and flexibility. 

There are at least five known methods of sealing acacia wood using spar urethane; spraying, wiping, rolling, and using a foam or bristle brush. 

Obviously, there is no clear way to choose and determine your project’s best method. It mostly comes down to your preference and skills. 

Some woodworkers prefer rolling or spraying as they are more effortless than other methods. Using a foam or bristle brush is more for those that prefer more meticulous work since this method can reach all crevices and spots of the wood.

spar urethane on wood

What Type of Spar Urethane Is Suitable for Acacia Wood?

There are two types of spar urethane you can choose from — water-based and oil-based spar urethane. When compared, there is only minimal difference between them, so it mostly comes down to what you need and requires for the wood. 

Water-based is preferred if you aspire to achieve a clear finish. Meanwhile, an oil-based one can acquire a cheaper and more stable finish.

What Are the Steps for Weatherproofing Acacia Wood?

You can waterproof acacia wood using a waterproofing finish like spar urethane. Apply 3-5 spar urethane coats along the wood grain and let each coat settle and dry for at least 24 hours. Ensure that each coat is dried completely before applying the next coat.

Upon applying spar urethane, the acacia wood should possess waterproofing abilities. That means you can now utilize acacia wood furniture for outdoor uses. 

The wood will withstand weather conditions like rain, snow, and humidity without risking its stability or durability. Waterproofing acacia wood furniture with spar urethane can make it viable and perfect for more uses and purposes!

wood pure tung oil

What Is the Recommended Exterior Oil to Use on Acacia Wood?

There are a couple of exterior oils you can use on acacia wood. Here are some of them:

To maintain the integrity and appearance of your wood furniture, it’s important to apply thin coats of oil and regularly clean the surface to prevent damage from environmental elements. 

Proper care and maintenance can significantly extend the lifespan of your wood pieces and keep them looking their best.

Recommended topics


Indeed, applying spar urethane to your acacia wood furniture can provide valuable benefits, including protection against harsh outdoor elements, enhanced durability, and an attractive finish. 

To achieve the best results, it’s important to apply the spar urethane in thin coats and allow each coat to dry thoroughly before applying the next one. This careful application process will help ensure the optimal performance and longevity of the finish.

robert headshot

Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.

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