Tung oil is a great wood finish that protects and revitalizes it, but many people are confused about whether it is a fire hazard or not. Other oil-based finishes, like linseed oil can be very dangerous, but is tung oil the same? This article will tell you everything you need to know about whether tung oil is flammable and how the additives in tung oil finishes impact its safety.
Is Pure Tung Oil Flammable?
Pure tung oil is not flammable. It has a flash point of 289 degrees Celsius (552 degrees Fahrenheit). This is the temperature at which the vapors will light from a spark or a flame. To be considered flammable, a substance needs to have a flash point below 93 degrees Celsius.
So, pure tung oil is not classified as flammable and it will not easily ignite under normal conditions.
That doesn’t mean that it won’t set on fire, but it does mean that you don’t have to be too concerned about it bursting into flames out of nowhere.
Are Tung Oil Finishes Flammable? 
Tung oil finishes are a different story to pure tung oil. The oil itself will not ignite, but the extra additives that you find in tung oil finishes often will. You tend to find things like mineral spirits, paint thinners, and petroleum distillates are added to make the finish easier to apply. These then evaporate, leaving behind the pure tung oil to protect the wood.
All of these additives are highly flammable and will easily ignite with a spark or a flame, even in normal conditions. So, if you are using a tung oil finish, you need to take extra precautions to prevent fires.
Will Tung Oil Catch on Fire when Exposed to a Flame?
It depends whether you are talking about pure tung oil or a tung oil finish. Pure tung oil will set on fire when exposed to a flame but as the flash point is particularly high, it can take a while. It won’t go up in flames immediately like more volatile products will.
Tung oil finish, on the other hand, will go up immediately because the other additives are incredibly flammable.
Can Tung Oil Catch on Fire from a Spark?
It is incredibly unlikely that tung oil will catch on fire from a spark because it needs to be heated to the flash point temperature before it will ignite easily. But if you are using a tung oil finish, it may light easily from a spark, depending on what additives are used.
For example, the flash point of mineral spirits is around 40 degrees Celsius (105 Fahrenheit), so if it is slightly above room temperature, it could go up with a small spark.
Can Tung Oil Catch Fire from High Temperatures?
Tung oil is an incredibly stable substance with an extremely high combustion point. So, even if it reaches high temperatures, it is unlikely that it will spontaneously combust without being exposed to flames. In some cases, a tung oil finish with additives may combust at high temperatures.
If I Leave Tung Oil in the Sun Can it Catch on Fire?
No, it is very unlikely that tung oil will get hot enough to combust just from being in the sun. If it has flammable substances added to it and it is in a sealed container, the heat can increase to dangerous levels and make it less stable, but this is not very common.
Having said that, if you are concerned about fire, it’s good to get into the habit of storing it out of direct sunlight anyway because other oil finishes will be dangerous in direct sunlight.
Is Tung Oil Flammable when Dry?
As tung oil dries, the reaction generates heat, increasing the chances of it setting on fire slightly (but this reaction only generates a small amount of heat so it doesn’t become particularly dangerous). However, once the oil is dry, it does not pose a serious fire risk at all, especially as it has soaked into the fibers of the wood.
The same is true of tung oil finishes. The additives like mineral spirits are incredibly flammable so the finish will burn easily when it is wet. However, these substances evaporate as the finish dries, leaving only the pure tung oil behind, so it is no longer flammable.
What’s the Safest Way to Dispose of Tung Oil?
If you have any excess tung oil, you should let it cure and harden properly before you dispose of it. Leave it exposed to oxygen and a reaction will take place, drying and hardening the tung oil. If you have containers, you can try cutting them open and laying them out somewhere to cure. Once the residual oil has cured, you can throw it in the trash.
Avoid pouring tung oil down the drain because you will end up with a serious blockage once it hardens.
Are Rags with Tung Oil on them Flammable?
Yes, rags with tung oil on them can be flammable. As the tung oil dries and the exothermic reaction generates heat, the temperature can build up, especially when the rags are all bunched together. If you are using a tung oil finish with flammable additives, this is a serious fire hazard.
Avoid any dangerous situations by drying out the rags properly before you dispose of them. Separate them and lay them out on a non-flammable surface like the driveway or patio. When they are fully dry, you can dispose of them in the trash or incinerate them. Alternatively, you can submerge them in water in a sealed container to neutralize the fire risk before throwing them out.
How Should You Store Tung Oil?
Tung oil should be stored away from heat sources and direct sunlight, especially if it contains flammable additives. Most importantly, you need to keep it sealed and away from oxidizing agents or it may cure in the container.
How Do You Safely Put Out a Tung Oil Fire?
If tung oil does catch fire, don’t try to put it out with a jet of water. This will only spread the oil and the fire instead of putting it out. If you have a dry chemical, carbon dioxide, or alcohol-resistant foam fire extinguisher, these will help you tackle it. If the fire is small and localized, try covering it with something non-flammable to starve it of oxygen.
Most importantly, don’t take any risks and call the fire department if you can’t control the fire.
Final Thoughts
Tung oil is one of the safer wood finishes out there because, in its pure form, it is not very flammable at all. But most tung oil finishes have things like mineral spirits or petroleum distillates added to thin it out, and these are flammable, so you need to take care while it is still wet.
Jamie is the founder of The Backyard Pros. When he was 15 years old he started working at a garden centre helping people buy plants, gardening products, and lawn care products. He has real estate experience and he is a home owner. Jamie loves backyard projects, refinishing furniture, and enjoys sharing his knowledge online.