best clear coats outdoor wood

10 Best Clear Coats for Outdoor Wood in 2021

In Buyers Guide by Jamie

Wood is, without question, one of the finest materials for manufacturing modern furniture, but it can also be somewhat susceptible to harsher conditions, specifically for outdoor use. To make matters worse, most wood finishes are incredibly messy, and the old-school polyurethane is an absolute headache to apply, and wait to dry.

Luckily, with a clear coat wood finish, you can greatly enhance the grain and overall appearance, plus, clear wood finishes are specifically designed for outdoor use, and low toxicity (VOC). Taking this into account, there are a few considerations you’ll have to make before your purchase.

What to Consider When Buying an Exterior Clear Coat Finish?

Its Durability and Water resistance

One of the most important things that you’ll want to consider when buying an exterior clear coat finish is the overall durability and resistance levels of the application. Keep in mind that all clear coat finishes are primarily designed to prevent the wood from rotting, and protect against UV and water damage, all while retaining the wood’s natural beauty.

All clear coat finishes fully cover the surface of the application, helping to prevent any chances of algae or mold growth that cause wood rotting. It will also ensure that your wooden materials are protected against those dangerous UV rays, moisture, and even rainwater that can cause peeling and fading over time. In addition, most clear coat finishes come in large gallon containers, which means that you’ll be able to cover a large surface area if need be. Plus, these products (on average) offer up to more than 10 years of instant protection against environmental hazards, vastly increasing the lifespan of the wood.

Also, clear coat finishes are also remarkably easy to clean, and even easier to apply. However, you will need to take into account what you’ll be using the coat for, and how durable you’ll need it to be. For example, high-traffic areas that are exposed to harsh weather conditions (railings, decks, sidings, etc.) are going to need more attention and may work better with different formulas. You’ll also want to go in with good knowledge on the difference between a water-based wood finish, versus an oil-based wood finish, as this too could sway your decision.

Is it UV Resistant?

As previously mentioned, clear coat finishes for outdoor wood are specifically designed to handle UV rays. However, since it will have to face the scorching sunlight every single day, you’ll need to consider whether it contains UV-resistant additives, called ‘UV inhibitors’ or ‘UV absorbers’. And if they even carry enough of these additives to be effective. Enhancing the wood’s durability with UV inhibitors will ensure that you shield your wooden materials from damaging UV rays for a longer duration of time. More specifically, Marine varnish is a spar varnish with a ton of UV inhibitors to better withstand prolonged sun exposure.

Type of Wood

The type of wood matters when applying a clear coat for outdoor use. Most of the time using one of the options below on our top 10 list will work fine, and hey, they will work on all types of wood no problem. However, certain wood items like various high-end furniture require proper care.

For example, teak furniture, which is known to be quite expensive may have a preferred method of weatherproofing. Teak has specific oils and sealers that work best to keep its natural beauty, while also holding up in the outdoor elements. We have a guide on the top 5 teak sealers you can check out here.

There are more types of wood that may need natural oils rather than just a simple clear coat, but it really depends on the piece you are sealing. Some examples of outdoor wood oils and sealers are:

  • Boiled Linseed Oil – Great natural product to use for wooden garden beds.
  • Teak Oil – Recommend for outdoor teak wood furniture.
  • Tung Oil – A great outdoor furniture sealer option.

Will it Turn Yellow?

Unfortunately, yellowing is a common complaint about clear coats. Urethane and oil-based topcoats are known for yellowing over time due to the chemicals infused to help them protect from the sun and its waterproofing properties. Keep in mind that a clear stain base will do nothing to stop the natural process of wood changing color, while a heavily pigmented stain will slow it, but not stop it entirely. That being said, if the final coating has a UV inhibitor (which many in our list below do), then this will help to fight against the changing of color.

If you are applying the clear coat over a white painted surface you are likely going to have yellowing in the finish.

10 Best Clear Coats for Outdoor Wood

1. Minwax Helmsman Spar Urethane (Water-based or Oil-based)

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The Minwax Helmsman Spar Urethane (water-based application) is undoubtedly one of the best clear coat finish for outdoor wood material. Not only does this application contain UV blockers, to help prevent any damage caused by the sun, such as intense cracking or fading over time. But it’s also specifically formulated to protect both interior and exterior woods from damage to sunlight, water, or temperature changes.

In fact, the crystal clear finish even forms a protective barrier against rain and moisture build-up. Plus, the special oils allow for the finish to expand and contract with the wood, regardless of the season and temperature. All in all, the Minwax Helmsman Spar Urethane is hands down the top-selling clear coat on the market for outdoor use due to its incredible versatility, and long-lasting features – plus it is found at a great price point.

Similarly, Minwax also carries an oil-based alternative that carries all the same features, with the exception of the type of polyurethane base. Water-based poly is typically a thinner product, while oil-based poly is a thicker product. Oil-based finishes generally carry a darker hue and require fewer coats, but they also take longer to dry and are more difficult to clean up. While water-based finishes carry much less VOC, which can help to minimize strong and potentially harmful odors to breath in and in the environment. So, there are certainly pros and cons to both options.

2. SEAL-ONCE MARINE

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SEAL-ONCE has been a market leader in terms of innovation for years, specifically in the use of nanotechnology to help create long-lasting, Eco-friendly wood sealers since 2005. Their exclusive MARINE application has been battle-tested to withstand high-moisture environments, and perform more efficiently for a longer period of time. Thanks to their advanced nano-particle technology, this premium sealer breaks below the surface of the wood, coating the wood fibers at a cellular level. Allowing it to form a superior barrier below the surface, giving it an additional layer of protection against water damage, and those deadly UV rays.

As well as any sort of warping, fading, rotting or mold/mildew growth that occurs. Not only that, but this impeccable wood finish is also entirely water-based, making it completely harmless to people, pets, or plants. All in all, the SEAL-ONCE MARINE finish is easily one of the best wood sealers on the market, encapsulating everything that one could ever need if a clear coat finish for outdoor wood.

3. TotalBoat Gleam Marine Spar Varnish

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TotalBoat Gleam Marine Spar Varnish is another exceptional alternative. This gorgeous finish contains premium tung oil and a phenolic resin formula that makes it ideal for clear coating applications. Not only that, but it’s also incredibly easy to use, and dries remarkably fast.

You will also have the option of either a Gloss or Satin finish, both of which contain Gleam 2.0’s fast-drying, easy-to-use formulas to ensure a stunning amber finish with all the necessary durability features as well.

 

4. Thompsons Waterseal

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Thompson’s Waterseal is another spectacular wood finish that’s designed to help protect all exterior woods and decking surfaces. Specifically, it’s able to repel water, prevent water damage, and resists mold growth, all while maintaining it’s natural wood grain. Long-lasting wood protection for your outdoor deck has never been so much easier. Plus, it also goes on clear, enhancing and maintaining the natural, elegant color of the wood. Thompson’s Waterseal also comes in a variety of other applications, including brick and even concrete. All in all, this sealer is undeniably one of the best clear coat finishes for outdoor wood items.

5. Varathane Ultimate Spar Urethane

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Another exceptional water-based solution, the Varathane Ultimate Spar Urethane is one of the most reliable finishes on the market. Featuring a protective ESC coat that offers ultimate UV and weather protection for outdoor wood projects. The formula easily applies and provides powerful resistance against graying, and weathering. Plus, the water-based finish expands and retracts with weather conditions, and lasts twice as long as the exterior oil-based alternative. And since it’s water-based, the clean-up will be quick, and you won’t have to worry about any lingering (and potentially harmful) odors in the environment.

Similarly, Rust-Oleum also carries a Varathane Ultimate Spar Urethane that is purely oil-based.

6. System Three Clear Marine Spar Urethane Varnish Coating

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System Three Clear Marine Spar Varnish is a high-build urethane that is specifically designed to withstand marine operations and glide along exterior wood surfaces for a clear, durable finish. It contains elite UV absorbers, which will help to protect the wood even against constant sun exposure. Plus, the System Three Marine Spar Varnish is resistant to scratching and marring, as well as countless harmful chemicals typically featured in certain cleaners and solvents. You even have the option of both Satin or Gloss finishes, beautifully illustrating the versatility you have with this varnish.

All things considered, the System Three Clear Marine Varnish is easily one of the top choices in terms of quality clearcoats designed for the outdoor wood application.

7. Rain Guard Water Sealers

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Another renowned, and incredibly affordable alternative, is the RainGuard Water Sealers for exterior wood. The immaculate thing about this finish is that it not only contains UV stabilizers, to ensure long-lasting non-yellowing performance. But it also is a highly-concentrated formula that is entirely water-based, making it more affordable and friendlier to the environment. The Rain Guard Wood Sealer uses architectural-grade silane siloxane technology to ensure that your surfaces are protected for years to come.

What makes this product so unique is its proprietary ingredient called MICRO-LOK. Which creates a mechanical bond giving you a hydrophobic barrier that’s totally unaffected by weathering, salt, dirt, freezing temperatures, UV light, and intense winds or rain. Taking this into account, the RainGuard Water Sealer for exterior wood is undeniably one of the best clear coats for outdoor wood.

8. Rust-Oleum Marine Spar Varnish

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Rust-Oleum slides into the 8th spot on our list, masterfully crafting one of the world’s finest wood varnish on the market. Its flexible oil-based formula expands and contracts to changing weather conditions, and its durable coating provides excellent resistance to UV, salt, and mildew. Plus, it takes only 2 hours to dry, covers up to 150 square feet, and is one of the most affordable clear coats for outdoor wood available. An obvious ‘no-brainer’ for our list.

9. Eco Advance Wood Siloxane Waterproofer

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The Eco Advance Wood Siloxane Waterproofer is a commercial-grade spray-on application that provides long-lasting protection for exterior woods, such as decks, fences, sidings, and more. Part of what makes this solution so unique is its vapor transmission abilities, which allow for increased durability, and prevent moisture from getting trapped, and damaging the wood. Specifically, it helps to protect against water damage, oil, stains, mold, mildew, de-icing salts, and pool/spa chemicals. Plus, this formula is entirely water-based, non-toxic, and non-flammable, making it safe for people, pets, or plants.

10. Clear Rust-Oleum Universal All Surface Spray Paint

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Finally, the Clear Rust-Oleum Universal All Surface Spray Paint is a two-in-one, paint and primer that’s designed for interior and exterior use to help provide long-lasting wood protection. Its comfort grip trigger delivery system eliminates finger fatigue caused by continuous spraying and allows a myriad of spraying angles to approach from. Plus, this universal spray paint works on nearly every surface imaginable, even some of the more pesky surfaces like vinyl, metal, plastic, fiberglass, concrete, glass, wicker, and (of course) wood. All in all, it’s an incredible oil-based formula that’s sure to help protect surfaces from the elements, rust, and corrosion for years to come.


Outdoor Clear Coat FAQs

Is Spar Urethane different from wood sealer?

Absolutely. If you’ve ever completed a woodworking project, then the chances are that you’ve likely encountered wood sealer or polyurethane before. This type of finish is one of the most versatile forms of finish on the market and typically comes in either an oil-based or water-based formula. Both of which are highly resistant to water, fungus and mildew, and typically come with an assortment of different gloss levels.

Whereas spar urethane is a specific type of finish that was designed to withstand the elements on the wooden poles that support the sails of a boat. Also known as the spars of a ship. Since this wood could withstand immense levels of moisture and wind, spar urethane was created to handle these same conditions. Now spar urethane is a common product used to weatherproof wood for outdoor use.

What is the difference between water-based and oil-based products?

As previously mentioned, when you’re in the market for a wood finish, you will be presented with two options; a water-based formula or an oil-based formula. Each with its own pros and cons.

Oil-based finishes use various petroleum and mineral solvents as the vehicle for polyurethane solids. Which helps to create a hard protective shell in fewer coats than the water-based solution. However, it is also more renowned for leaving a slightly yellow sheen, especially with multiple coatings, and typically dries much slower. On the plus side, it is also self-leveling, meaning that it will become smooth when applied to a horizontal surface.

Whereas water-based wood finishes use water rather than solvents as the base for carrying the polyurethane solids. Like the oil-based polyurethane, water-based solutions can form a hard protective shell as well, but you’ll need to apply more coats. However, since water-based applications dry quickly, more coats can be applied in less time than with oil-based products. Plus, water-based polyurethane contains almost no odour, is easy to clean, eco-friendly, and typically void of any potentially harmful chemicals to pets, people, or plants.

There’s certainly a difference between the two, but each carries its own separate list of positives and negatives.

Can I Use Epoxy on Outdoor Wood?

Epoxy is a tremendously popular and durable material that chemically bonds with the surface that it’s attached to, and cures hard to ensure a long-lasting effect. Not only is Epoxy durable and long-lasting, but it also requires minimal maintenance, and can even be used outside. However, for outdoor use, often a UV inhibitor will need to be added to the epoxy mix or the wooden project will quickly fade in color.

When it comes to wood projects, Epoxy is a tempting choice because it can last nearly half a lifetime if installed correctly. Meaning that you won’t need to worry about fixing or replacing your outdoor wooden surfaces every few years. However, it will need to be installed correctly, or you may find that mold and water seeping underneath your epoxy finish.

Final Thoughts

If there’s one thing that homeowners have always struggled with, it’s keeping outdoor wooden furniture looking the way it did on the showroom floor. Unfortunately, UV rays, water, and mildew pose serious threats for your wood to rot, and lose it’s value. Luckily, there’s a reliable and efficient way to extend the life of this natural material, polyurethane protective wood finishes.

So long as you follow along in the presented guide, you should be able to find the ultimate solution for your home furnishings in no time.