December 21, 2022
Even today, many woodworkers I’ve talked to consider tung oil as one of the best finishes for wood. But what is tung oil, and why does it receive so many positive reviews as a wood finish?
Tung oil belongs to the most popular oil finish for wooden furniture. It is also referred to as China wood oil. This oil is derived from the tung tree nut seeds pressed thoroughly to produce the oil. It is said to have originated in China based on the writings of Confucius. As such, it gets also referred to as China wood oil. Through polymerization, this oil hardens quickly when exposed to air, resulting in a transparent coating with a deep wet look.
What is Tung Oil?
Tung oil is mainly used to protect and finish wood after applying several coats. The resulting finish has a wet and deep look that is almost plastic-like. Other oils related to the tung oil include linseed, poppy, safflower, and soybean oils.
If you use raw tung oil, it tends to dry well and provides a wrinkled finish. So, to create a wrinkled finish, you can use natural tung oil with a cobalt drier. You can prevent this wrinkled finish by heating the oil to make it gas-proof.
Varnish and paint manufacturers use tung oil as a generic name for the finishing products they produce that contain raw tung oil. These products offer a finish similar to the finish provided by raw tung oil.
Characteristics and Properties of Tung Oil
Woodworkers who love the ecosystem also love to use tung oil because it is considered green, meaning, it is made of natural ingredients and doesn’t carry VOCs. Besides, it provides a natural look to wood without creating a glossy finish. Furthermore, it doesn’t darken or enhance the growth of mold. If you intend to use it, it will be best, however, to learn the following advantages of its use.
- Tung oil provides good protection to wood and offers resistance to moisture.
- It enhances the beauty of the wood and doesn’t encourage mold growth.
- It offers a durable and flexible finish and provides a faster drying time compared to other oils
- It doesn’t necessitate an extra sealer, for it already works as a natural sealer for the wood.
- It is not hard to clean, and it is eco-friendly.
- It offers a lovely matte finish for the wood that is not entirely glossy.
How Does Tung Oils Work on Wood?
Tung oil is one of the finishes you can use to protect the wood. You can hand-rub this oil onto the wood to preserve and amplify the appearance of the wood. Moreover, you can use it for finishing boat decks, flooring, wood furniture, unfinished wood, concrete floors, weathered wood, stone, countertops, cabinetry, bamboo, musical instruments, brick, and wood toys.
Once you apply tung oil onto the wood surface, it doesn’t only sit on the top surface of the wood. Instead, it permeates and imbues the deep wood fibers and integrates itself with the wood.
Besides, after curing and drying, it produces an excellent non-oily finish. If you use it for finishing wood furniture, it cures slowly and produces a golden-colored hue. Furthermore, if you use pure tung oil, it will never alter its color over time.
Different Types of Tung Oil
You might get confused as you search for the ideal tung oil for your wood finish because there are different types of tung oils. Hence, it will be best to know the following different types of tung oils:
1) Pure Tung Oil
You can quickly identify pure tung oil because it is devoid of solvent content. The use of pure tung oil, therefore, is safe because it doesn’t expose you to VOCs. Nevertheless, it is not easy to apply, and it takes time. It will be best to let two to three days pass to harden every coat. Besides, you need to apply five to seven coatings to achieve a protective film. If you use a thick coat or rush the process, you might have a wrinkled wood surface that requires sanding.
The produced surface, however, is lovely and gorgeous if you follow the correct application of tung oil. Moreover, you need to reapply tung oil every week for the duration of one month. After which, you only need to apply once every month for the first year.
2) Modified Tung Oil or Tung Oil Finish
This type of tung oil is a tung oil product that offers the finish of a tung oil but dries faster and harder. These products often come with metallic drying agents, oil additives, or thinners and carry the name “Tung oil Finish.” With the additives, the penetration of these tung oil products gets enhanced, and the drying time becomes faster. Besides, the price of these products becomes more reasonable.
These modified tung oil products, of course, provide excellent finishing products for consumers. Yet, they do not work or behave the same way that pure tung oil would. Moreover, this product only has a limited tung oil amount. Besides, some of them might not even have tung oil.
3) Polymerized Tung Oil
Many woodworkers who use tung oil often complain about the length of time it takes to cure this product after application. Thus, to reduce the curing time, vendors have come up with a formulation called polymerized tung oil. This product has undergone a cooking process to hasten the drying process.
Advantages of Using Tung Oil
If you’re a beginner in the use of tung oil as a wood finish, it will be best to know the advantages of its use. This way, you can decide whether it is the best finish for your wood project:
You may think all furniture oils and other wax blends can make wood surfaces waterproof. Yet, it is not always the case. Remember that drying oils don’t really dry out. Besides, they disintegrate into something other than oil, and this process is called polymerization. So, it will be more proper to say that tung oil doesn’t remain oil but turns into a polymerized oil.
Tung oil absorbs around twelve percent of oxygen when applied to wood to create a waterproof surface layer. As it reacts to the oxygen in the atmosphere, it continues to polymerize, creating a thin and water-resistant layer or film over the wood surface.
Tung oil is derived from the berry seeds of a tree named Vernicia fordii. It externally looks like a nut. Besides, it is non-allergenic unless, of course, you have an allergic reaction to nut oil.
Resistant to Mold
One of the issues that usually arise from the use of oil is whether an oil finish encourages mold growth. Most synthetic and oil-based finishes exhibit decolorization as they age. Pure tung oil, however, resists the growth of mold. So, you can expect no mold growth if you use raw tung oil to finish the wood surface.
Doesn’t Necessitate Sanding
Tung oil produces a smooth surface finish that offers clarity and beauty. Thus, when you properly apply tung oil on your wood projects, you don’t need to sand the surface to make it smoother because this finish itself makes the wood surface look good.
Disadvantages of Using Tung Oil
To figure out whether tung oil is the best finish for your project, it will also help if you are familiar with the following disadvantages of its use:
When you apply tung oil, you will smell a mild odor that could irritate your nostrils. However, over time, this odor dissipates. The smell becomes less noticeable, however, if you would coat the tung oil with wax, lacquer, polyurethane, or shellac.
Takes Longer to Apply and Dry
Tung oil application and drying may take a whole month compared to other oil finishes that dry quickly. Besides, you can only place wood finished with tung oil in direct sunlight after the oil has fully cured because it will get damaged. When applying tung oil, you should check the surface for ten days. Clean the surface using a clean cloth.
When the oil is curing, ensure that you don’t put any heavy load on the wood. Besides, you should prevent dirt and mud from hitting or landing on the wood surface because this can make the wood surface tacky. Moreover, you will find it hard to do away with this dirt once it lodges on the wood. Wait until the tung oil seals the wood and completely cure.
Slowly Penetrates the Wood Surface
It will be good to note that tung oil penetrates the wood slowly. You will need around six or more coats to ensure that the oil has entirely penetrated the wood and created a protective layer over the wood. Thus, applying this oil to your wood project will take time and effort.
It will be best likewise to sand the wood surface every after coat. Besides, it will take around three to four days for a coat to dry completely and penetrate the wood.
Tung oil is more expensive than other oil finishes. It is around twenty-five percent more costly than different oil finishes. Thus, if you don’t want to spend more on finishes, you should avoid using tung oil.
How to Apply Tung Oil on Wood?
You can dilute one part oil with solvent. Afterward, you can apply the resulting solution successively using a lint-free cloth like an old cotton t-shirt. The solvent you can use range from turpentine to citrus-based thinners. Your choice, however, would hinge on how fast you want the coating to set. For example, you can use Naphtha if you use the spray-on technique.
You can follow a 1:1 thinner-to-oil ratio for the primary coats and successive layers. However, if the wood finds it hard to absorb the solution, you can increase the solvent-to-oil ratio. This type of solution can produce a matte finish and the deepest color for your wood.
At the start, you can use thinned pure oil for deep penetration of the wood surface, allowing the oil to fill the pores. Afterward, you can apply straight oil to let it adhere moderately to the wood surface, providing a robust base for further layers. Afterward, you can apply a polymerized oil finish to provide a single thick layer to dry well.
Then, you can buff using very fine sandpaper. Use also use 0000 steel wool for further smoothing of the surface. Wipe the surface using a moistened rag and let it dry. Afterward, you can apply a thick final coat and let it dry for three days.
Most Common Questions on Tung Oil
Aside from knowing what tung oil is and the pros and cons of its use, it will also help if you are familiar with the FAQs about tung oil, for they might also be the questions you have in mind:
What Are the Challenges Concomitant with the Use of Tung Oil Finish?
Using tung oil can present several challenges to its users. First, the application of this finish requires time and effort. Besides, the curing time takes longer. Thus, you need to apply additional coats for maintenance.
You can make this additional application every six months or annually. Moreover, it is not free of irritating odors.
How Many Coats Should You Apply Tung Oil to the Wood?
You will need up to five coats to produce a good finish using tung oil. Remember that it takes up to three days for a coat to harden. So, it will take more time for you to finish the applications of all the needed coatings for this oil.
Linseed oil vs. Tung Oil: Which is Better?
Linseed oil and tung oil are usually compared to each other because they are the most common oil finishes used for wood. Linseed oil is derived from flax seeds. It is, therefore, less expensive than tung oil. It also dries faster. Linseed oil may provide a beautiful finish you would indeed love to see.
Tung oil, on the other hand, offers better hardness and durability. Besides, it provides better waterproofing of the surface. Tung oil also doesn’t darken over time. Both, however, are natural and eco-friendly.
Tung oil had been used for centuries in China. It had long provided a water-resistant finish to wood, enhancing wood projects’ durability. Besides, it had long given a beautiful finish to wood that many have appreciated. Tung oil doesn’t darken or exhibit mold growth over time, though you need to make additional applications over time to preserve the looks of your wood project.
If it is your first time using tung oil, it will be best to learn the pros and cons of its use. Knowing the pros and cons can help determine whether it is the best finish for your projects. Nevertheless, if you apply this finish properly, you can expect a lovely result that rivals the best finishes in the market today.
Liam is a 37-year-old woodworker and interior designer who loves to make every furniture project an art piece. He is very experienced in furniture design and woodworking project planning.