There’s a wide range of fast-drying exterior wood sealers on the market. So, what does Tung oil offer that they don’t?
Sure, pure Tung oil will sink right into wood grain, protecting lumber from moisture damage. But, how long will that Tung oil coat last on outdoor furniture?
Well, in this post, you’ll learn what actually goes into a lot of Tung oil products. You’ll also discover how long a pure Tung oil coat can last (before it needs to be reapplied).
And keep reading to find out if this natural finish is really the best way to weatherproof your outdoor furniture.
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What Is Tung Oil? Is It A Good Wood Finish?
Tung oil is a natural drying oil finish that’s been extracted from the seeds of the Tung tree. Its been used for centuries as a wood preserving finish.
Once Tung oil dries and cures into a hard solid coat, it prevents wood from readily absorbing water. And, what’s more, the thin film coat it forms on the surface of wood is fairly water-repellent too.
Now, while this oil finish enhances the look of timber, it does not waterproof it. Plus, while it forms a fairly hard coat, it is not the most durable finish either.
And a freshly cured Tung oil coat will need to be reapplied every 6-12 months. That is, unless, you top coat a Tung oil finish with a durable sealant, such as Polyurethane.
What About Outside? Can Tung Oil Be Used Outside?
Yes it can. In fact, it is one of the only truly natural drying oils that can be freely used on exterior wood.
You see, Tung oil is a very slow curing finish. It can take a few days for it to dry, but it can take up to 30 days to cure.
However, this natural oil doesn’t go rancid the way that Raw Linseed oil can. So, mold and mildew won’t grow on a Tung oil finish as it slowly cures.
What Is The Difference Between Drying And Curing?
A dry finish has gone through a process of evaporation. This is when the finish turns from a viscous liquid into a solid (yet still soft to the touch) film.
However, curing is a chemical reaction that turns an oil finish into its final hardened coat.
Related Post: Tung Oil Not Drying? (3 Simple Ways To Fix It)
And How Long Does Tung Oil Last On Wood Outside?
Without the help of a top coating sealant, a Tung oil finish will need to be reapplied within 6-12 months. That is because between rain and humidity, Tung oil’s surface film will wear off.
However, if you apply a durable sealant coat over Tung oil, then it can last up to 10 years.
Still, Tung oil alone won’t be enough to waterproof outdoor wood, which can leave timber at risk of wood rot.
Yet typically, using Tung oil on outdoor pieces doesn’t pose a problem. This is because the wood we use for outdoor furniture needs to be naturally rot-resistant in and of itself.
Therefore the job of Tung oil on outdoor furniture is to be more like a wood preservative, than a sealant.
Related Post: Can You Really Use Decking Stain On Garden Furniture?
Does Tung Oil Darken Wood?
Pure Tung oil is a clear finish. It won’t darken lumber any more than say a splash of water can.
However, there are certain types of so-called Tung oil products that will darken the color of wood.
You see, a lot of marketed Tung oil products aren’t actually Pure Tung oil. In fact they don’t even contain much (if any) Tung oil in them. Instead, they’re made from a blend of natural oils (such as Linseed or Tung oil), paint thinners, and varnish.
These fake-Tung oil products can darken wood, particularly if they happen to contain Linseed oil. Still, if you just stick to Pure Tung oil, this finish won’t drastically change the color of your outdoor furniture.
Related Post: Can You Use Tung Oil On Cherry Wood? (Avoid These 3 Simple Mistakes)
But Is Tung Oil Weather Resistant? Can It Protect My Furniture From UV Damage?
No, it cannot. Pure Tung oil isn’t going to be enough to seal and waterproof wood. And it certainly isn’t going to safeguard outdoor timber from UV color-fading damage.
If you want to truly make your outdoor furniture weatherproof, you need to ditch Tung oil altogether. And instead, top coat your garden set with a more durable sealant, such as Spar Urethane.
And What Is Spar Urethane?
Spar Urethane, (also known as Yacht Varnish), is probably one of the most water-resistant sealants on the market.
Thanks to this sealants urethane ingredient, it keeps moisture out, while still having enough flexibility to allow wood to ‘breathe’. Which is why Spar Urethane is widely used to coat decking and marine vessels.
What’s more, a quality Spar Urethane product will also contain UV inhibitors to help protect wood from color fading. And this sealant needs less maintenance than Tung oil, as it only needs to be reapplied once every 5 years.
Nonetheless, it’s worth noting that Spar Urethane does have a tendency to make wood look a bit plastic. Once dry, (which takes around 2hrs), this sealant can make wood appear as though its been sealed in Saran wrap.
To Wrap Up, Here Are The 3 Key Takeaways From This Post…
- 1). Tung oil is a slow-drying natural oil finish that can be used on outdoor furniture.
- 2). It is a fairly water-repellent wood finish, but it is not waterproof or weather-resistant.
- 3). If you want to protect outdoor furniture from weathering, then use a more durable exterior sealant, such as Spar Urethane.
He Z, Qian J, Qu L, Yan N, Yi S. Effects of Tung oil treatment on wood hygroscopicity, dimensional stability and thermostability. Industrial Crops and Products. 2019 Nov 15;140:111647.