Use an outdoor-rated finish like polyurethane, epoxy, lacquer, or varnish. Make a natural oil finish with one part tung or linseed oil, one part mineral spirits, and one part polyurethane. Use a stain sealant combo that gives your wood some color and a durable finish all in one.
Do you have wood furniture for your outdoor patio or kitchen? If you take a few extra steps, you can ensure the wood lasts for years to come. If you leave untreated wood outside, it can age quickly. You don’t want that to happen!
To treat wood for outdoor use, you don’t need a professional. If you’re new, it can take some time to learn. We’ll show you three quick ways to do it and ensure you make as few mistakes as possible.
For a quick introduction to treating wood for outdoor use, check out the video below. This homeowner treats his Western red cedar table with West Systems epoxy and oil-based Epiphanes varnish.
It’s OK if you’re not familiar with what finish you want, the difference between the finishes, or how to apply them. We’ll go over all that and more in detail.
Method 1 – Apply an outdoor-rated finish: polyurethane, lacquer, varnish, or epoxy.
You have several options for outdoor finishes. Four of the most popular are polyurethane, lacquer, varnish, and epoxy. Application techniques vary depending on the product, but we’ll give you a general idea of how to apply your finish.
Clean the wood completely before applying the finish. If the wood is already finished, sand it off before applying a new one.
Note: If you’re applying the same finish and it’s not too old, you don’t need to sand it off. Just clean the wood thoroughly.
Most wood finishes last several years. They are not permanent but definitely increase longevity. After you treat wood once, the process will go much quicker in the future!
Here’s the materials list; it’s not exhaustive but should cover the basics to get you started.
What You Need
Your outdoor finish of choice: polyurethane, lacquer, varnish, or epoxy (refer to the can to determine the finish’s coverage)
Paint stirring stick
Bristle paintbrush
Fine sandpaper
Electric sander (optional)
Vacuum cleaner
A couple of rags
Distiller if necessary: water for water-based sealants, mineral spirits for oil-based sealants
1. Lightly stir the finish.
If you stir the finish too vigorously, air bubbles can form which can make it difficult to apply.
2. Dip a bristle brush about halfway into the finish. Begin applying it as evenly as possible.
When applying your finish, go with the grain. Don’t overload the brush, as this can cause drips and an uneven coating.
3. Let the finish dry.
Wait two to four hours for water-based sealants, or about six to eight hours for oil-based sealants. Overnight is great too. When you let the finish dry, keep the furniture out of the sun. In colder months, keep it covered so it doesn’t get rained or snowed on.
4. Lightly sand the finish with fine sandpaper: 120 grit or finer.
The higher the number, the finer the sandpaper. As you apply more coats, use finer grit sandpaper. For example, ideally use finer grit sandpaper after your third coat compared to your first coat. Finer sandpaper is much gentler on the wood.
5. Wipe off excess dust.
6. Repeat steps 2-5 until you have three to five coats of your finish. The exact number of coats may vary depending on the type of finish.
Oil-based finishes require fewer coats than water-based finishes.
Again, this is just a general guide on applying finish to outdoor wood. Always defer to the manufacturer’s instructions when applying your finish, as not all finishes are the same.
Polyurethane
Polyurethane is a durable plastic resin. Polyurethane sealants come in different styles including gloss, semi-gloss, and satin. Satin is the least reflective of the three, while high gloss finishes are shiny. They reflect a lot of light.
When treating wood, you have the option of water-based polyurethane or oil-based polyurethane. Oil-based sealant takes longer to dry than water-based, but it doesn’t require as many coats. It’s also higher in VOCs than water-based polyurethane.
Can my gutters overhang my Neighbours?
It is a well established principle that you own the airspace above your land, so if your neighbour's gutters overhang your land then they may be a...
Oil-based poly requires mineral spirits, turpentine, or acetone to clean up, while water-based poly comes off with soap and water.
Polyurethane is available for indoor and outdoor use. You can use the outdoor sealant indoors, but not vice versa. So make sure you have the right product before starting your project!
Lacquer
Lacquer is an ultra-durable high-gloss finish made by dissolving tree sap in alcohol or turpentine. You can find lacquer in many different sheens. Lacquer thinner makes lacquer easier to apply to your wood finish.
It’s best to apply three to five coats of thinned lacquer to your wood. The fumes can be pretty unbearable so make sure to open windows and doors when applying this finish.
Varnish
Varnish is made up of drying oil (such as linseed oil), tree resin, and a solvent, like alcohol. Once applied, varnish hardens as the solvent evaporates. Depending on the solvent, some varnishes harden quickly while others take time to cure.
Varnish is highly water and UV-resistant It is thinner than most polyurethane solvents. It requires more coats and can take a long time to dry. Varnish is naturally glossy but you can find it in a wide variety of sheens.
When treating wood for outdoor use, look for varnish with high UV resistance. Marine varnish is a good option. This durable finish was originally used on boats and ships.
Epoxy
Epoxy is made up of epoxy resins, organic compounds that come from plants. It’s a durable finish often applied before varnish or lacquer.
Not all epoxy is rated for outdoor use. All epoxies will eventually yellow over time when exposed to sunlight, but those meant for outdoor use are more UV-resistant.
Check with the manufacturer before you start treating your wood. Some epoxy resins work well at filling in cracks in wood as the resin seeps into the hard-to-reach areas with ease. Not all epoxies are thin enough to do that, though. In the video above, a full coat of epoxy was applied, dried, and sanded down before applying the varnish.
Method 2 – Seal with linseed oil or tung oil.
Linseed oil is made from flax seeds while tung oil is made from seeds of tung trees native to Southern China. These oils are typically combined with mineral spirits and polyurethane to make a durable finish for outdoor wood.
After you’ve applied the oil-based sealant, place any oily rags in water. As the oil dries, it generates heat and the rag can spontaneously combust. After it soaks in water for a few minutes, ring out the rag and let it dry before throwing it out. Do not reuse oily rags.
We’ll go over the step-by-step process to make and apply this sealant.
Here’s the materials list; it’s not exhaustive but should cover the basics to get you started.
What You Need
Tung or linseed oil
Polyurethane
Mineral spirits
Wood stirring stick
Bristle paintbrush
Fine sandpaper
Electric sander (optional)
Vacuum cleaner
A couple of rags
1. Combine one part tung or linseed oil, one part polyurethane, and one part mineral spirits.
Here are a few Amazon links for linseed oil, tung oil, and mineral spirits.
2. Stir the mixture thoroughly but gently to avoid forming air bubbles.
3. Dip a wall paintbrush halfway into the finish. Apply the sealant with the grain.
Make sure the wood is cleaned and sanded before you apply the finish. In between coats, sand your wood with fine sandpaper once dried.
Oil-based sealants yellow over time. So this finish is best on dark woods like walnut or cedar rather than light woods like pine.
Can I use a shed as a garage?
When used as a garage, a shed allows you affordable added storage space to park an automobile, lawnmower, or other large equipment. Furthermore, a...
4. Let the oil soak into the wood for a few minutes. Reapply oil to any dry areas.
5. Wipe off all excess oil so it absorbs evenly into the wood,
6. Let the wood dry for roughly six to eight hours. If your sealant has more oil, it will take longer to dry.
7. Sand the wood with 120-220 grit sandpaper or finer. As you paint additional coats, use finer sandpaper.
8. Repeat steps two to seven until you’ve painted about three to five coats. Oil-based sealants require fewer coats than water-based sealants.
Method 3 – Use an all-in-one stain-sealant combo.
Stain sealant combos add color and a durable finish to your outdoor wood. Here’s a stain-sealant combo from Amazon that works great. If you like the look of unfinished wood, stay away from stain-sealant combos. Stain-sealants typically last a couple of years before they need to be reapplied.
Do I use a brush or paint sprayer to apply an outdoor finish?
Typically, brushing is better because it allows more of the sealant to soak into the wood than a sprayer. Using a paint sprayer is faster than a brush but more surface level. Spraying also doesn’t leave brush strokes.
Diluting Sealants
Oil-based sealants
You can thin oil-based sealants with turpentine, acetone, or mineral spirits. Most people go with three or four parts sealant to one part mineral spirits. If the finish is particularly thick, you can go with half spirits and half finish.
Water-based sealants
Thin water-based sealant with water. You can use similar ratios to thinning oil-based sealants: three to four parts sealant to one part water. Add water in small quantities and mix the sealant so you can ensure you get the right consistency.
If you’re applying the same finish that was used before – and it’s not too old – just clean the surface well. Then dry it and reapply your finish.
if you’re applying a different finish, it’s discolored, or it’s severely aged, then remove the old one. The coarser the sandpaper, the easier the finish will come off. If sanding isn’t working or takes too long, use a paint or stain stripper to remove the old finish. Don’t use steel wool as it can lead to rusting.
Applying finish over paints and stains may change the color of your finish. Chances are high it won’t look attractive.
Recap
We know that was a lot of information! Hopefully you learned something from this post to help you treat your wood for the outdoors! Remember that you have three methods to treat your wood:
Use an outdoor-rated finish like polyurethane, epoxy, lacquer, or varnish. Make a natural oil finish with one part tung or linseed oil, one part mineral spirits, and one part polyurethane. Use a stain sealant combo that gives your wood some color and a durable finish all in one.
Check out more of our outdoor content at the links below!
Related Articles
How to Clean Outdoor Furniture (Complete Guide)
How to Make Outdoor Furniture Last
How to Clean Outdoor Cushions
As an Amazon Affiliate, we may earn from qualifying links.
DIY Builds
Photo: Kuriakose John
Promotion