Tung oil and linseed oil are two popular wood-finishing products derived from trees or plants. They are used to enhance the appearance of the wood while protecting it from moisture, humidity and rot. Both tung and linseed oils can be used for a wide variety of applications, though each has its own distinct advantages for certain projects.
Tung oil is derived from the nuts and seeds of the Tung tree, which is primarily found in China. The nuts and seeds are harvested and pressed to release the oil, with each nut having about a 20 percent oil content.
Lineed oil comes from the seeds of the flax plant, which is grown in central Europe and Asia. The seeds are pressed or ground to release the oil, which has a natural yellow coloring similar to vegetable oil.
While wood refinishing and sealing is one of the main uses for these oils, both also have other uses in manufacturing and industry. Tung oil is used to prevent rust in cars and tin cans, and also to insulate electrical devices. It is frequently applied to boats and other marine structures to minimize rot and mildew over time, and is added to many paints and solvents. Linseed oil is used to make linoleum flooring, caulk and a wide variety of paints and stains. It is also used as a nutritional supplement, as are the flax seeds themselves. Many modern surfboards are coated with linseed oil to improve their water-resistance.
When applied to wood, tung oil produces a very shiny finish that some homeowners may find desirable. It is also non-toxic and can be used on kitchen tables and other food-based applications. Tung oil also greatly improves the water resistance and anti-wear properties of wood, especially outdoors.
Linseed oil is generally easier to apply than tung oil and is also non-toxic. It creates a glossy sheen on wood, but not the high level of shine associated with tung oil. For some users, this sheen is considered much more attractive than a high shine.
The primary drawback to tung oil is that it is derived from tree nuts. For some allergy sufferers, exposure to tung oil can be problematic or deadly. This material also tends to darken to an amber hue over time, which may be undesirable in some applications.
Linseed oil is highly combustible and poses a fire risk to users. It is not as waterproof as tung oil and does not penetrate wood as well when applied as a finish. It also tends to turn yellow over time as it interacts with oxygen in the air.
No matter which of these oils is used to finish wood, they must be reapplied often, usually every six months to one year. They can be applied with brushes, sprayers or a clean rag. Tung oil must be allowed to dry completely, then sanded between each coat. It is very porous, and the oil must be reapplied until the wood no longer absorbs another coat. This can be a very time-consuming process, as it often takes days for each coat to dry. Linseed oil can often be applied in a single coat, and does not always need to be sanded depending on the application and desired finish.