How to Seal Wood for Outdoor Use

Seal and finish wood outdoor with lacquer.

Many things can happen to wood if it is left outdoors without sealing it. It can expand or contract due to the vicissitudes of weather. It can also turn gray over time. In the worst case, it can decay and rot, sans an extra protective layer. Thus, sealing outdoor wood once or twice yearly would enhance its longevity and help maintain its quality.

If you’re an aspiring woodworker, you must learn how to seal wood for outdoor use. Of course, sealing the wood might require a lot of dirty work, yet it is a step that you should not miss. You can seal wood using a waterproofing agent. This way, your wood will never be susceptible to discoloration, decay, expansion, or contraction.

Why Should You Waterproof Outdoor Furniture?

One of the greatest natural enemies of wood is moisture or water. The wood will contract or expand when exposed to high humidity, leading to warping or swelling. It can also decay and discolor over time. You can protect the wood from these eventualities by sealing it. Besides, sealing wood protects it from moisture, UV rays, insect attack, and even frost. 

If you fail to seal your outdoor wood furniture and decks, you will soon be replacing them. Nevertheless, if you seal and maintain them regularly, they could last for several decades or more. 

Things to Know Before Sealing Outdoor Wood

If you intend to seal outdoor furniture, it will be best to be cognizant of the following few things. This way, you can seal the wood properly and provide it with sufficient protection against the harsh outdoor elements:

  • Some pieces of wooden furniture require waterproofing, while others don’t. Thus, before sealing a piece of outdoor furniture, it will be best to know if it necessitates sealing. Research the type of wood you will use outdoors before buying a sealant. If the furniture is made of hardwood like teak, it will not require sealing. 
  • When sealing painted wooden furniture, you need to do an extra step when sealing. First, thoroughly clean the wood surface using wood-safe detergent, a cleaning brush, and water. Let the wooden furniture dry for three hours before you move on to the next steps.
  • Carefully choose the sealant you will use for your wood. Remember that sealants come in a wide variety. Some types, for example, offer a matte finish, while others provide a glossy finish. Thus, it will help if you choose the sealant to furnish your outdoor furniture with the desired finish. 
  • Ensure you do the sealing in a well-ventilated area. Sealants exude fumes that could be injurious to your health. Besides, you should wear safety gear like gloves and masks when sealing the wood.

Methods of Sealing and Waterproofing Outdoor Wood Furniture

If you intend to seal outdoor wood or furniture, it will be best to know the different sealing methods and waterproofing wood. This way, you can choose the most suitable method of sealing your outdoor wood. The following are the various methods of sealing wood:

1) Using Varnish

You can seal wood using varnish. But before you use varnish, you should know the pros and cons of its use. Varnishing can provide wood with a certain level of protection against moisture and water. It will not alter the wood’s color, making it look natural. It also provides ample protection from UV rays because it absorbs UV rays. 

Thus, you can expect your wood to be protected from UV ray damage, preventing wood discoloration. Experts would recommend the use of marine varnish for your outdoor furniture. This type of varnish resists moisture better than other types of varnish. 

2) Using Polyurethane Sealants

Another method you can employ to seal wood is using polyurethane sealants. Polyurethane sealants have polyurethane resins and acrylic resins. They also carry different solvents, allowing for various options when choosing this method. You can choose from a wide array of polyurethane sealants, ranging from soft sheen to high-gloss shine. 

The good thing about contemporary polyurethane sealants is that they don’t turn yellowish over time. Besides, oil-based polyurethane provides optimum durability for your wood. Nevertheless, cleaning up the brush you’ve used would require turpentine or mineral spirits. 

On the other hand, the use of water-based polyurethane offers a less messy cleanup. Oil-based polyurethane also offers better waterproofing properties. So, it will help if you go for an oil-based polyurethane sealant when sealing outdoor furniture. 

You only need to apply two coats of polyurethane sealant, which is easier than using varnish, which requires at least eight coats. However, you should use polyurethane carefully because it contains volatile compounds that could be health and fire hazards. 

3) Using Lacquer

You will find lacquer in different sheen options. Lacquer is a durable option that enables the wood to last for fifteen years without damage or decay. Lacquer is a sealant made of dissolved synthetic resin or tree resin. This resin gets dissolved in alcohol. 

Lacquer may turn yellowish over time, making wood a bit unattractive, especially if the wood is lighter in color. Yet, it can enhance the warm and rich color of deep-toned wood. 

You can buy lacquer in different sheen options and thin it using thinner. You can get optimum results from lacquer by applying multiple coats onto the wood. 

As a caveat, lacquer exudes pungent fumes that could harm and irritate your nostrils and respiratory system. So, it will be best to do the sealing outdoors or in a well-ventilated room. 

Lacquer is thinner than polyurethane or varnish. Thus, it allows for deeper penetration of the wood fibers and provides excellent protection. Besides, the finish offered by lacquer is scratch-resistant.

4) Using Latex Paint

Another excellent option to seal outdoor wood is using latex paint. Paint can block UV light, protecting wood from damage caused by sunlight. Besides, it can prevent the discoloration of wood and many other issues caused by exposure to UV rays. 

Latex paint provides better protection for outdoor wood than oil-based paints. As such, it will be best to use latex paint than regular paint. 

Latex paint offers a wide array of color options, and its use can hide those unsightly scratches. If you apply latex paint correctly, you can expect better protection for your outdoor furniture against outdoor elements like UV rays and water. 

You can also reapply paint over the wood surface after a few months if you see dents, scratches, and peelings in some parts of your furniture.

5) Using Stained Sealant

Another excellent option is the use of stained sealant. The use of stained sealant can provide your wood with up to ten years of protection before reapplying this sealant. The stained sealant also provides your wood with sufficient waterproofing. Besides, the stain adds extra pigment to your wood; the sealant offers an additional layer of protection. 

The sealing compound in most stained sealants is polyurethane, while the stain may vary depending on the pigment concentration. Thus, you can get various levels of glossiness from different types of stained sealants. 

As a caveat, it will be best to remember that stained sealant also carries volatile compounds. Thus, it will be best if you are extra careful when using a stained sealant. 

6) Using Epoxy

Epoxy consists of organic compounds and epoxy resins. It offers a long-lasting and durable finish that you can apply before you apply lacquer or varnish. Nevertheless, it will be good to note that you can’t use all types of epoxies for sealing outdoor furniture. 

The reason is not all types of epoxies are suitable for outdoor usage. Besides, all epoxy sealants will turn yellowish over time. Thus, you need to add lacquer or varnish to it. 

Before buying epoxy, consult with the manufacturer to know if the epoxy you are buying is best for outdoor. You can choose epoxy that could fill in cracks and fix minor wood damage. 

Nevertheless, you can’t expect all epoxies to be sufficiently thin to fill those cracks. Thus, you need to consult with the manufacturer to determine if the one you’re buying suits outdoor usage. 

How To Make Outdoor Wood Weather-resistant?

The most viable way to weatherproof outdoor wood is by using wood stain or sealant. Wood sealant can provide your wood with a transparent layer of finish, while wood stain can add pigment that will alter the wood’s tone and appearance. When sealing the wood, it will be best to employ the following steps:

Step 1: Prepare Your Wood

Before staining or sealing the wood, the first thing you need to do is prepare the wood surface. The best way to prep the wood is by sanding it. You can use rough sandpaper for the initial sanding. This way, you can tackle the wood imperfections and do away with the old treatment. 

Afterward, you can finish sanding using finer grit sandpaper. Ensure you clean the wood surface after you sand the wood to remove any dust residue. 

If you buy ready-made furniture, you might not need sanding because the furniture might have been already sanded. So, you only need to wipe the wood surface using a clean and dry rag. 

Step 2: Select the Stain or Sealant You Will Use

As mentioned above, the right choice of sealant will provide your outdoor furniture with the best protection. So, you must carefully choose the sealant you will use. Once you’ve chosen the suitable sealant, you can apply multiple coats of this sealant on the wood surface. 

If you want optimum protection for your wood against UV light, you can go for latex paint because it provides better protection against UV rays. 

If you want a natural look for your outdoor wood, you can go for an exterior spar varnish that also carries UV blockers. Refrain from using deck stains or other finishes that don’t provide sterling protection for wood. 

Step 3: Apply the First Coat

When applying the first coat, you must apply it evenly using a sprayer or brush. Let the sealant dry for five to ten hours. You must follow the manufacturer’s instructions to ensure the best results for your wood. Ensure that every part of the wooden furniture gets finished. 

Fill every crack and seal every crevice of the wood furniture. Ensure that you apply a sealant to the joints and the underside of the furniture. Besides, ensure the legs and their bottoms get sealed. 

Step 4: Sand the Wood Surface

Once done with the first coat, you can start sanding the wood surface. This way, the following coat will stick well with the first coat. Use fine-grit sandpaper to sand the first coat. Afterward, wipe the wood surface using a dry cloth. 

Step 5: Apply the Second and Third Coat

Once you’ve cleaned the wood surface, you can apply the second coat and let it dry completely. Remember that the succeeding coats might take longer to dry. Once the coat dries, follow the same steps and clean again. Then, apply the succeeding coat until the final coat is applied. 

Step 6: Let the Coats Cure

Drying is different from curing. You let each coat dry to prepare it for the next coating. However, once you have applied the final coat, you allow it to cure. Thus, curing is drying the layer entirely before using the furniture. 


Sealing wood is an essential process for most outdoor wood furniture. Remember to do this process if you want your outdoor wood furniture to last longer. Sealing wood, of course, takes time and effort. Yet, it is worth doing because it can make your outdoor wood last for decades. 

If it is your first time sealing the wood, you can follow the abovementioned steps in sealing outdoor furniture. This way, you can do the sealing process correctly. Recoating outdoor wood is also imperative. So, you must not forget recoating your outdoor wood regularly. 

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