3 Methods To Waterproof Wood Furniture For Outdoors

If you've just bought wood furniture for your deck or patio -- or if the finish on your current outdoor wood furniture has worn off -- it's time to protect it from the elements by sealing it with a waterproofing agent. So, what's the best way to waterproof your outdoor wood furniture? We've done the research, and we have the answers for you!

There are three types of waterproofing agents for outdoor wood furniture:

Natural oils: linseed oil or tung oil
Clear coats: varnish, polyurethane, or lacquer
All-in-one stain + sealant

In this article, we'll examine the advantages and disadvantages of each product and provide step-by-step directions for waterproofing your wood furniture. We'll also discuss why it's important to seal your outdoor wood furniture and answer common questions about how best to protect it from damage due to moisture and UV rays. Keep reading to learn more!

Why Waterproof Outdoor Wood Furniture?

Outdoor wood furniture is exposed to the elements -- wind, sun, rain, and frost -- leaving it vulnerable to swelling, warping, discoloration, and rot unless it is sealed. When you seal your outdoor wood furniture, you protect it against moisture and UV rays, insects, and frost.

Without sealing, your furniture will likely need to be replaced within a few years; if you seal and maintain it properly, though, it can last two decades or more.

Three Methods Of Waterproofing Wood Furniture

There are three methods of waterproofing wood furniture: rubbing it with natural oils, sealing it with a clear coat sealer, and applying a stain-plus-sealer to it.

Natural Oils

Using natural oils, such as linseed or tung oil, is the easiest way to seal your outdoor furniture. It is also the least toxic, as natural oil products do not contain the VOCs (volatile organic compounds) produced by synthetic sealers. However, natural oils provide only moderate protection against the elements, so you should use this option only on furniture that is well-sheltered.

Linseed Oil

Linseed oil is a non-toxic and eco-friendly product that has been used for thousands of years. Like all hand-rubbed oil finishes, it penetrates deep into the grain and brings out the wood's natural beauty. Linseed oil protects against moisture and humidity. On the negative side, it does not provide as strong a barrier as synthetic sealers do. It can also yellow over time.

There are three varieties of linseed oil products, each with its own advantages and disadvantages:

Raw linseed oil - provides the best look and protection when you apply several thin coats. However, each coat takes at least two weeks to dry, so treating your furniture with this product is probably not feasible.
Boiled linseed oil (which, despite its name, is not boiled or heated in any way) - has petroleum-based or heavy-metal drying agents added to it. While these extra ingredients substantially reduce drying time, they also emit harmful VOCs.
Polymerized linseed oil - features the best of both worlds: it consists of pure linseed oil, heated until it thickens substantially. With no VOCs and a short drying period, polymerized linseed oil can be applied in several thin coats over the course of two or three days.

Click here for polymerized linseed oil on Amazon.

Tung Oil

Tung oil is derived from Chinese tung tree seeds, another eco-friendly, non-toxic finish for outdoor wood furniture. Like linseed oil, it works best when applied in multiple thin coats; and it dries about as quickly as polymerized linseed oil does. Additionally, tung oil does not take on a yellowish hue, making it a better choice for maple and other light woods. Tung oil creates a harder surface layer than linseed oil, so it resists moisture and scratching better.

Click here for tung oil finish on Amazon.

Step-By-Step Instructions For Applying Natural Oil To Outdoor Wood Furniture

Tools/materials needed:

Orbital sander and 80-grit sandpaper (if your furniture is weathered or has old finish on it)
Deck cleaner and stiff-bristled brush
Polymerized linseed oil or tung oil
High-quality natural bristle paintbrush
Mineral spirits
Clean rags

Step-by-step instructions:

If your furniture is weathered or has an old finish on it, start here:

Sand your furniture thoroughly. A 5" or 6" orbital sander with 80 grit sandpaper works best.
Mix one part deck cleaner with four parts water; using this formula and a stiff-bristled brush, scrub the furniture.
Rinse the deck cleaner formula off the furniture; allow it to dry completely.

If your furniture is new and unfinished, start here:

Using a high-quality natural-bristle paintbrush, apply a thin coat of oil to the furniture. Make sure to get oil into all the nooks and crannies and between the slats.
Once the wood is saturated, wipe the furniture with clean rags to remove excess oil.
Immediately after wiping, place the rags in a bucket of clear water; otherwise, they may spontaneously ignite.
Clean your paintbrush in mineral spirits.
Allow the furniture to dry overnight.
Apply a second and, if necessary, a third coat in the same manner. Allow each coat to dry for 30 minutes before applying the subsequent coat.
Following the application of the last coat of oil, allow the furniture to dry for 24 hours.

Clear Coat Sealers

Unlike natural oils, which seep into the body of the wood, clear coat sealers form a hard, shiny skin atop it. This skin provides better protection against moisture and scratches, but it also peels away after a time and must be sanded off before the wood can be refinished.

Oil-based clearcoat sealers darken the appearance of most types of wood. They also contain potentially hazardous VOCs that natural oils do not. There are three major categories of clearcoat sealers: varnish, polyurethane, and lacquer.

Varnish

Exterior varnish -- especially marine varnish -- offers unbeatable protection against moisture and UV rays. It cures to a flexible coat that will not crack under the stresses of exposure to the elements.

The major downside of varnish is that its initial application is time-consuming and laborious: you must apply eight thin coats, letting each coat dry fully before applying the next. When the finish begins to look filmy every two to three years, you will need to sand it lightly and then apply a new topcoat.

Click here for marine varnish on Amazon.

Polyurethane

Often erroneously believed to be the same as varnish, polyurethane is, in essence, a liquid plastic that forms a thin coat over wood, impervious to water and highly resistant to scratches and dents. Both water-based and oil-based polyurethanes are available, but only the oil-based variety is appropriate for use on outdoor furniture.

Oil-based polyurethane creates an appearance similar to that of varnish; however, it requires only two coats instead of eight. On the negative side, polyurethane has higher levels of VOCs than varnish has.

Click here for polyurethane on Amazon.

Lacquer

Lacquer provides the extremely-high-gloss finish that is often found on Oriental cabinetry. It is durable and resistant to scratching, but over time it tends to become discolored.

Lacquer is thinner than polyurethane or varnish; in the past, it was typically applied with a sprayer rather than a brush, but recently manufacturers like Minwax have developed excellent-quality brush-on varieties. Lacquer contains high levels of VOCs.

Click here for wood lacquer on Amazon.

Step-By-Step Instructions For Applying Clearcoat Finishes To Outdoor Wood Furniture

Tools/materials needed:

Protective equipment: respirator or N-95 protective mask
Orbital sander and 80-grit sandpaper (if your furniture is weathered or has old finish on it)
Deck cleaner and stiff-bristled brush
Oil-based varnish, polyurethane, or lacquer
High-quality natural-bristle paintbrush
Mineral spirits

Step-by-step instructions:

If your furniture is weathered or has old finish on it, start here:

Sand your furniture thoroughly. A 5" or 6" orbital sander with 80 grit sandpaper works best.
Mix one part deck cleaner with four parts water; using this formula and a stiff-bristled brush, scrub the furniture.
Rinse the deck cleaner formula off the furniture; allow it to dry completely.

If your furniture is new and unfinished, start here:

Wear a respirator and work outdoors or in a well-ventilated area.
Using a high-quality natural bristle paintbrush, apply a thin coat of varnish, polyurethane, or lacquer to the furniture. Make sure to work the finish into all the nooks and crannies and between the slats.
Clean your paintbrush in mineral spirits.
Allow the furniture to dry overnight.
Apply additional coats in the same manner: 8 thin coats of varnish; 2-3 coats of polyurethane or lacquer.
Follow the manufacturer's instructions and allow each coat to dry completely before applying the subsequent coat.
Following the application of the last coat of finish, allow the furniture to dry for at least 24 hours.

All-In-One Stain + Sealer

To add rich color and enhance the grain of your wood furniture while simultaneously protecting it from water and UV rays, use an all-in-one stain and polyurethane sealer. These products are available in a wide array of tints and with shine values ranging from flat to glossy.

They allow you to achieve color, shine, and protection in two easy coats. All-in-ones have the advantage that they do not yellow or darken over time. Like other polyurethane products, they contain VOCs.

Click here for stain + sealer on Amazon.

Step-By-Step Instructions For Applying All-In-One Stain + Sealer To Outdoor Wood Furniture

Tools/materials needed:

Protective equipment: respirator or N-95 protective mask
Orbital sander and 80-grit sandpaper (if your furniture is weathered or has old finish on it)
Deck cleaner and stiff-bristled brush
Oil-based all-in-one stain + sealer
High-quality natural-bristle paintbrush
Mineral spirits

Step-by-step instructions:

If your furniture is weathered or has an old finish on it, start here:

Sand your furniture thoroughly. A 5" or 6" orbital sander with 80 grit sandpaper works best.
Mix one part deck cleaner with four parts water; using this formula and a stiff-bristled brush, scrub the furniture.
Rinse the deck cleaner formula off the furniture; allow it to dry completely.

If your furniture is new and unfinished, start here:

Wear a respirator and work outdoors or in a well-ventilated area.
Using a high-quality natural bristle paintbrush, apply a thin coat of all-in-one stain + sealer to the furniture. Make sure to work the finish into all the nooks and crannies and between the slats.
Clean your paintbrush in mineral spirits.
Allow the furniture to dry overnight.
Apply a second coat of all-in-one stain + sealer in the same manner.
Allow the furniture to sit for at least 24 hours before placing cushions or other articles on it.

How Often Should You Oil Wood Furniture?

If your wood furniture is indoors or in a well-protected outdoor setting, you should oil it once per year. However, if it is exposed to the elements, apply oil twice per year or more in order to give it the most protection.

The bottom line is if your wood furniture begins looking dry or weathered, apply a new coat of oil, making sure to work it into all the corners, nooks, and crannies to keep the wood water-resistant and looking good.

How Do You Seal Wood Without It Getting Darker?

To seal your wood without changing its color, coat it with a water-based polyurethane or water-based acrylic lacquer. These products provide a shiny finish without darkening the wood. Oil-based sealers, by contrast, bring out the yellows and oranges in pine and darken most other woods. Natural oils also tend to yellow over time, changing the look of the wood.

How Do You Protect Wood From UV Rays?

All of the options described above will protect your wood furniture from the sun's UV rays. Water-based polyurethane and water-based lacquer are especially effective for use on indoor furniture. Linseed oil and tung oil work well on stained outdoor furniture.

In some cases, especially on reclaimed wood whose color you do not want to alter, furniture wax can provide an effective barrier against UV rays while maintaining that old, weathered look.

Does Paint Protect Wood Outdoors?

Paint labeled for exterior use is designed to seal and protect wood from the elements. Before you apply paint to any wood that will be used outdoors, first clean it and remove any old finish; then apply a coat of wood primer rated for exterior use. After the primer dries, apply two or three coats of exterior paint, allowing each coat to dry before you apply the next one. For all types of wood except wicker, you may use either oil-based or latex paint; on wicker, use oil-based paint.

Should You Waterproof Wood Before Painting?

There is no need to waterproof wood before painting it, as long as you use exterior-rated primer and paint. These finishes have sealing elements built into them; so, by thoroughly applying both primer and paint to every inch of your wood furniture, you will achieve the waterproof result you're looking for.

In Closing

Protecting your outdoor wood furniture from moisture and UV rays is essential to keeping it strong and looking great. For a natural, glowing appearance, use linseed oil or tung oil. To preserve the wood's color and grain while giving it maximum protection from the elements, apply one of the clear coat sealers.

Or, to add a stain color and protect your furniture, select an all-in-one stain + sealer. Whichever option you choose, you can keep your outdoor wood furniture looking and functioning like new for years to come!