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This article compares two different kinds of penetrating oil wood finish: tung oil and Danish oil.
- What Is Tung Oil?
- What Is Danish Oil?
- Tung Oil vs Danish Oil
- Major Distinguishing Factor
- When to Use Tung Oil
- When to Use Danish Oil
- Which Is Better, Tung Oil or Danish Oil?
What Is Tung Oil?
Tung oil is a penetrating oil finish. While film finishes like polyurethane or varnish sit on top of the wood, oil finishes soak into the grain. Penetrating finishes do not peel or crack with age.
Tung oil has been used to protect wood from water for thousands of years. It is mentioned in the writings of Confucius as an effective sealant for boats.
Harvested from seeds at the center of nuts that fall from the tung tree, tung oil is a transparent liquid with a golden tint. 100% tung oil is non-toxic and food safe. Although it is a vegetable oil, tung oil does not turn rancid.
Tung Oil Uses
It is popular for use on wood that will be exposed to the elements, since penetrating finishes are more flexible than film finishes. Tung oil in particular is known for its flexibility, allowing the wood it protects to expand and contract without disturbing its protection.
Tung oil is sold in two formulations; natural or pure tung oil, and dark tung oil. Natural tung oil will dry to a gently golden glow. Dark tung oil has a rich brown color. Either product enhances the appearance of wood while providing long-lasting protection.
Tung Oil Characteristics
Unlike water based finish, oil finishes work through a process called oxidation. As oxygen molecules are introduced to drying oils such as tung, linseed, or walnut oil, a phenomenon called crosslinking occurs. As a result, the oil becomes a stable yet flexible solid barrier that reinforces the structure of the wood.
As alternatives to wood are developed, such as biocomposite boards made from hemp shives and cornstarch, new applications for tung oil emerge. Applying tung oil to biocomposite boards significantly increases their compressive strength.
Tung oil not only repels water, it also confers resistance to pests and fungi. This is due to the naturally pest-resistant and fungus-resistant properties of the tung tree, where the oil comes from.
Unlike other finishes such as teak oil, tung oil does not contain any additives to speed its dry time. While tung oil dries to the touch within a matter of hours, the natural curing process can take two to three days.
What Is Danish Oil?
Danish oil is a wood finish made from a combination of varnish, drying oil, polymers, and solvents. There is no defined formulation for Danish oil, nor are there regulations governing what can be labeled as Danish oil. As a result, it’s difficult to know exactly what you’re getting when you purchase a product marketed as Danish oil.
However, this term can be generally understood to refer to any oil/varnish mix with more oil than varnish. This is referred to as a ‘long oil’ finish. The usual ratio is one part varnish to two parts oil.
Varnish is a film-forming finish, so it forms a barrier on top of wood. Drying oils are penetrating finishes, where the barrier is constructed by filling in space below the surface of the wood. Danish oil is therefore a film-forming and penetrating finish.
The oil used could be any of a number of different drying oils, although tung oil and linseed oil are the most prevalent. Polymers and solvents are added to Danish oil improve dry time and make the finish easier to apply.
Tung Oil vs Danish Oil
Since Danish oil is an inspecific marketing term, it is difficult to truly compare these two products. Danish oil could contain tung oil, linseed oil, or another drying oil. It might include mineral spirits or other solvents.
However, there are a number of clear likenesses and disparities between the two finishes.
The similarities between tung oil and Danish oil include their resistance to water, risk of spontaneous combustion, and aesthetic effect on wood.
Wood treated with tung oil or Danish oil becomes resistant to water damage.
Both finishes come with a risk of spontaneous combustion. Drying oils release heat as they turn from liquid to solid. The thin layer of oil applied to wood doesn’t pose a fire risk, but wadded up rags soaked with drying oil certainly do.
When wet rags are thrown in a trash can, the heat released by the drying oils has nowhere to go. When the cloth reaches it’s flashpoint, or the temperature at which ignition spontaneously occurs, a dangerous fire can be the result.
To eliminate the risk of causing a fire with oil-soaked rags, lay them out over the rim of the trash can or on a drying rack. Once they are dry, they will not release any more heat, and it is safe to dispose of them.
Both tung oil and Danish oil will change the color of the wood. Pure tung oil imparts a golden glow similar to shellac, and the color stays true over time. Dark tung oil adds brown tones to the wood, and is similarly colorfast. Danish oil darkens wood, and tinted versions can be used as a stain.
These penetrating oil wood finishes have much in common, but there are important differences as well.
Tung oil comes from the tung tree, which is naturally resistant to pests and fungi. This resistance is passed on to wood treated with tung oil. Danish oil sometimes contains tung oil, but often contains linseed oil. Linseed oil does not have the same natural resistances.
Wood treated with tung oil is usually described as having a matte finish. Danish oil provides a shinier satin finish.
100% tung oil is safe for use on serving dishes and wooden utensils. There’s no way to know what exactly is in Danish oil, since every manufacturer makes their own formulation with various drying oils, varnishes, solvents, polymers, and other additives. This makes it unacceptable as a finish for surfaces that will come into contact with food.
Tung oil is all-natural and completely non-toxic. No additives, solvents, or polymers have been added to tung oil, so it does not release any harmful or toxic gases. Danish oil includes varnish, which is toxic if ingested and dangerous to inhale.
Major Distinguishing Factor
The biggest difference between tung oil and Danish oil is the time each product takes to cure.
Pure tung oil naturally cures to form an impermeable yet flexible barrier within two or three days, depending on the environment.
Danish oil contains ingredients like solvents and polymers that help speed the drying and curing phases. Danish oil dries faster than tung oil.
When to Use Tung Oil
Use tung oil to protect interior and exterior wooden furniture from water, pests, and fungi.
Tung oil’s natural golden glow enhances the appearance of wood while also helping it last longer. It is easy to apply, non-toxic, and food safe.
When to Use Danish Oil
Use Danish oil when you don’t have enough time to use tung oil.
Danish oil is more expensive than tung oil, ostensibly due to the polymers, solvents, and other additives that manufacturers include. These speed up the time it takes for the oil finish to cure, which is helpful if you’re in a crunch to finish a project.
However, the performance of the finish is not affected. Danish oil doesn’t last longer or provide better protection than tung oil, so there is really no reason to pay the increased price tag, unless you have to have something fast drying.
Which Is Better, Tung Oil or Danish Oil?
Tung oil is better than Danish oil. It has no environmental or health impact, provides long-lasting and durable protection for wood, and is flexible enough to handle widely varying temperatures. If you prefer the darker look of Danish oil to the golden hue of pure tung oil, dark tung oil is the perfect substitute.
The only advantage Danish oil has over tung oil is dry time. Danish oil dries in about six to ten hours, depending on the formulation. Tung oil takes several days to fully cure.