We know we repeat ourselves, but water is the enemy of wood. To this, we want to add another: the sun’s UV rays are also the enemy of wood.
Each will lead to the deterioration of wood fiber, weaken the wood, lead to decay and rot, and eventually make wooden furniture unusable even as firewood. It really is sad to see a piece of outdoor furniture graying, listing to one side, and eventually collapsing. The same would be true of indoor furniture, too, except that it doesn’t rain inside, and the sun doesn’t shine through the roof.
Wood surfaces need to be protected from both outdoors. If you’ve made a table for the outdoor patio or purchased some unfinished chairs for the deck, it’s essential to protect them from the elements. Whether stained or painted, they need “shelter from the storm,” as Bob Dylan sang.
How to do that? Well, happy you asked because that’s what we want to write about today. The steps aren’t hard; they are very similar to what you do to finish that dining room table or that kitchen cutting board or cabinets. The difference when it comes to outdoor furniture is what you use to finish the wood.
How Best To Protect Outdoor Wooden Furniture
Rain, snow, sun. Enemies that need to be thwarted. The damage they can cause over time to your outdoor wooden furniture, if untreated, will put you back to work in the shop for a new table or chairs for the patio or deck.
So, we need something that will be waterproof, and we need something that will block the harmful UV rays of the sun.
We wrote an article once about how to care for an exterior mahogany door. Mahogany isn’t inexpensive, and such an investment needs to be protected well from the elements to protect that investment.
Perhaps that patio set you built or the Adirondack chairs you built for the garden aren’t made of mahogany, but you worked hard on them. You’re happy with the results of that work, and you want them to last a long time.
A sealant of some kind to keep moisture out of the wood fibers and some color that will block UV rays will do the trick for you. In those categories, you have a number of products to choose from, and we don’t mean just brand names.
You have three basic categories of protective products to choose from:
- Combo stain/sealants
We will offer some thoughts and suggestions on each to help you make informed decisions for your outdoor wooden furniture.
Weatherproofing Wooden Furniture With Oils
Boiled Linseed Oil
We like hands-on finish applications and enjoy that tactile satisfaction of rubbing the wood with oils. Linseed and Tung oil comes to mind for several reasons, and we’ve used both to good advantage on our projects.
Linseed oil is derived from the flax plant, and we’ve written of it often, actually. The stalks and seeds are used to produce flax oil, now referred to as linseed oil. That oil has been used to preserve wood and rope for centuries, with the earliest written record of its use dating back to the 6th century CE.
It penetrates deeply when applied to raw wood, strengthens the wood, and protects it from the elements. Although it can be brushed on, we prefer cloth and our hands, and subsequent yearly application will continue to penetrate the wood and extend its protection.
When frustration with the drying time necessary when using raw linseed oil boiled over, so to speak, boiled linseed oil was developed to shorten that drying time to a matter of days. Actually, it isn’t literally boiled; rather, oil that has been heated is pushed through linseed oil, and drying chemicals (naphtha and mineral spirits) are added to speed along the time to dry and cure.
It will protect the wood from moisture and UV rays, so is a good choice for outdoor furniture. It is highly water-resistant but technically not waterproof. Yet, with an annual refresher application, it will maintain the natural beauty of the wood and continue to protect it from the elements.
Another oil we have used is Tung oil, sometimes referred to as China Tree Oil, as the Tung tree is native to eastern Asia. The seeds of the Tung tree nut are squeezed to extract the oil, and its use as a wood preservative dates back to at least 400 BC, where its mention was found in the writings of Confucious.
It, too, is used as a wood preservative today, and we like the hand-rubbed finish it provides to outdoor wooden furniture. It’s often used on boat decks and outdoor concrete, even for its protective qualities.
Tung oil provides a harder and more durable finish on wood than does boiled linseed oil. It is also more water-resistant than boiled linseed oil and dries quicker than raw linseed oil.
However, it is also more expensive, is slower to penetrate the wood, has an off-putting odor, and is difficult to store. Yet, it does enhance the natural beauty of wood and offers good protection against the elements.
You can enhance each of these oils by blending them with 1 part each of mineral spirits and polyurethane for a hand-rubbed solution that will enhance the water resistance of each oil alone. Blended oil finishes are also available to purchase, too, and we will discuss combination finishes (stain and sealant in one) later in this piece.
The added protection that polyurethane will provide will supplement the natural water resistance of the oils alone and create both a penetrating finish and a film layer over the wood. At the least, boiled linseed oil is probably already among your shop’s inventory of wood finishes, as are polyurethane and mineral spirits, so making your own at that ratio will be easy with products already on hand.
Waterproofing Wooden Furniture With Sealants
Among the most common sealants for wood finishing is polyurethane, varnish, and lacquer. These reliable and trusted sealants provide excellent water-proofing protection to outdoor wooden furniture, and we’ve used all of them with good success.
A couple of rules apply when using any of these sealants:
- Ventilation. Each contains chemical solvents that can be annoying in the environment, so make sure you find a well-ventilated room. Actually, since you are finishing furniture for outdoor use, use them outdoors.
- Temperature. Each applies better when used at room temperature – whatever you consider that to be, whether indoors or outdoors.
- Do not disturb. Do not stir vigorously or shake the container before use. This will create air bubbles that will not look good on the wood even after the sealant has dried.
We’re sure you’ve worked with one or more of these sealants and don’t need any particular instruction on their use. The containers do a good job of offering directions, so just make sure you’ve familiarized yourself with each product before use.
Weatherproofing Outdoor Furniture With Combination Stains/Sealants
We like the use of combo products and have good success with them. We’ve also written about a number of such products in the past and will note those past articles for a deeper dive into the use of each as we go along.
Waterlox To Protect Outdoor Wood
Waterlox will provide a protective finish on outdoor furniture that will guard against UV rays and exposure to water and harsh weather conditions. It’s a resin-modified tung oil product that is worth considering for your outdoor furniture preservation.
Thompson’s WaterSeal Waterproofing Stain
The reason is in the name. It is a combination of stain and water sealant and is commonly used on boat decks that take a beating from both the sun and the weather. That’s really all you need to know about it as an outdoor furniture finish.
In a past article, we recommended it as a good choice to protect an expensive mahogany exterior door, even. You can find that piece here.
Ready Seal To Protect Outdoor Wood
Another combo 2-in-1 product is Ready Seal Exterior Stain and Sealer For Wood. It’s easy to apply and comes in a variety of colors, and is specifically designed for exterior wood finish use.
Requiring no primer, it goes on dark and reaches its final color in a couple of weeks. Its self-proclaimed “goof-proof” quality leaves no streaks or runs and can be applied in any temperature.
Cabot Semi-Transparent Stain to Protect Outdoor Wood
This combination product is a linseed oil-based penetrating stain is a single application product that will protect wood from UV rays with a water-repellant quality to its application. Its light pigmentation lends itself to almost any wood, including mahogany.
When properly applied, it won’t crack or peel. Because it’s not fully water-proof, though, a sealant like varnish will extend the life of the wood as an added measure of protection. It’s not quite a combo stain/sealant, but it is worth considering for your outdoor furniture.
There are just some of the many products that will keep your outdoor furniture well-protected from the elements. Some will need re-application from year to year, while others will last longer. Each will do its job for you, though, and help you enjoy that garden bench or gazebo, or patio table and chairs for a long time.
To offer you a wider variety of products and results, we found a video from a woodworker who has built a lot of outdoor furniture in two environments with wide ranges of temperatures and sun exposure. You’ll see his real-world experience with Adirondack chairs, and it’s pretty interesting.
Due diligence will help you decide on the right outdoor furniture protective finishes that will best suit your needs. Just be sure to protect your furniture well, and it will last you for a long time.