Whether you're refinishing furniture or trying your hand at woodworking, there's no doubt you've found yourself staring at the wall of oil finishing products at the hardware store, wondering which of the multitude of finishes is the right one for you. Even if you narrow it down to two of the most common, tung oil and linseed oil, there are still so many options to choose from.
At first glance, they seem similar. They're both oils that leave wood with a beautiful, natural-looking finish, both are easy to apply, and they aren't too far off in price. So, how do you know whether tung oil or linseed oil is better suited for your application? We've broken down the major differences between tung oil and linseed oil, as well as their strengths and weaknesses, and clarified which oil is best for different applications.
Tung Oil vs. Linseed Oil: Major Differences
To the untrained eye, tung oil and linseed oil seem very similar. However, these oils have key differences that make them very different from one another. Because there are so many impure versions of these two natural oils, it's necessary to note that many of the listed qualities are only true of the purest forms. Always pay close attention to the additives in your specific product and follow proper safety measures for application and use.
|Major Differences: Tung Oil vs. Linseed Oil|
|Pure Tung Oil||Raw Linseed Oil|
|Source||Extracted from the nuts of the tung tree||Extracted from flaxseeds|
|Color||Dries clear, but will add slight color to lighter woods||Dries slightly yellow, but will worsen over time|
|Dry/Cure Time||Two to three days||Several weeks|
|Durability||High||Low, prone to scratching|
|Maintenance||Requires regular reapplication||Requires regular reapplication|
|Toxicity||Non-toxic to humans and pets in pure form, once fully cured||Non-toxic to humans and pets in pure form, once fully cured|
|Food safety||Food-safe in pure form, once fully cured||Food-safe in pure form, once fully cured|
Varieties of Tung Oil
Odds are, if you head to the hardware store and purchase a can of tung oil, it won't be pure tung oil. This is because companies have figured out that they can capitalize on the recognizable name of tung oil, while only featuring slight amounts of pure tung oil cut with many additives. These additives aren't inherently bad and won't cause the finish to fail, but the resulting product can't be likened to 100% pure tung oil.
Pure tung oil is incredibly thick, which makes application slow and curing times even slower. The impure tung oils on the hardware store shelves will most often feature additives. Such as drying agents to cut down on drying time, resins for added durability and sheen, and solvents to make application quicker and easier. While these additives compromise the non-toxicity of the pure stuff, they make tung oil a more accessible and sometimes better finishing option for applications that don't require non-toxicity or food safety.
Because every version of tung oil features a different set of additives, each one may call for different application techniques, drying times, and safety measures. Pay close attention to product labels before use.
Varieties of Linseed Oil
Like tung oil, linseed oil has changed over the years. Raw linseed oil is a great natural finish, but it takes a significant amount of time (several weeks between coats). Because of this, it's a pretty impractical product for everyday DIYers. The solution? Boiled linseed oil.
Boiled Linseed Oil. Boiled linseed oil isn't actually boiled—anymore. There was a time when the oil was boiled and lead was added. This allowed the several-week cure time of raw linseed oil to be drastically shortened, making the product more useful on a wider scale.
However, as you can imagine, adding lead to the linseed oil also took away its non-toxic, food-safe qualities. These days, boiled linseed oil still features safer metallic or petroleum-based driers to help speed up the drying process. These additives cause the linseed oil to emit VOCs, making it toxic and non-food-safe.
What are VOCs?
VOCs are the common shorthand name for volatile organic compounds. These chemicals have a high vapor pressure at room temperature, causing them to off-gas after application. For this reason, items with VOCs require extended periods of time for off-gassing before they should be used.
Polymerized Linseed Oil. Unlike boiled linseed oil, polymerized linseed oil is heated for a long period of time while starved of oxygen, which causes a polymeric reaction to occur. Once the oil is polymerized, it's more viscous but has drastically shorter drying times. Put simply, the linseed oil is changed on a molecular level but remains additive-free, which keeps the oil free of VOCs.
Pure tung oil has a beautiful matte finish that allows the wood to pop, without drastically tinting or yellowing the wood's natural hue. Impure tung oil products may add more color to the wood. Tung oils with additives can vary in appearance and sheen.
Linseed oil lends an amber hue to wood that will yellow over time. This visual effect is much more noticeable in lighter woods such as birch and maple. Once dry, linseed oil has a satin sheen.
Best for Appearance: Tung Oil
The clear, matte finish of tung oil makes it a go-to for those that want a natural finish with protective qualities.
Tung oil is water resistant, preventing water molecules from seeping into the wood's grain. This is due to the curing process, during which the tung oil reacts with the oxygen in the air to form a hard protective barrier on the outside of the wood.
Linseed oil has much less water resistance than tung oil. While the oil is hydrophobic (like all oils), it is susceptible to water damage. This means that it may slightly protect the wood beneath from spills and water exposure, but the finish itself can be damaged as a result.
Best for Water Resistance: Tung Oil
When it comes to water resistance, tung oil is superior to linseed oil and will offer much more water protection in any application.
|Best Uses for Tung Oil vs. Linseed Oil|
|Pure Tung Oil||Raw Linseed Oil|
|Regularly used furniture pieces||Yes||No|
|Ornamental furniture pieces||Yes||Yes|
|Wooden bowls and spoons||Yes||Maybe|
|As a touch-up oil||Yes||Yes|
Care and Cleaning
Tung oil can easily be wiped clean with a damp cloth. But, for more intense cleaning, water-vinegar mixtures can be used as well as oil soaps and even some mild household cleaning products. Always ensure the products are non-bleach and test on hidden areas before full application.
Linseed oiled surfaces can be wiped with a slightly damp cloth. However, too much water can damage the finish. For more intense cleaning, a mixture of turpentine, vinegar, and linseed oil is recommended. The turpentine and the vinegar will do the heavy-duty dirt lifting while the linseed oil protects and maintains the finish.
Best for Care and Cleaning: Tung Oil
Properly applied tung oil is much easier to clean than linseed oil, as it can be cleaned with readily available commercial cleaning products and is much more forgiving when cleaned with water.
Durability and Maintenance
Pure tung oil creates a very durable finish for wood when properly applied. The finish soaks into the wood and cures to form a barrier that is highly water-resistant and scratch-resistant. To maintain durability and water resistance, tung oil finished items should be cleaned and recoated regularly if seeing normal use.
Wood finished with linseed oil is much more durable than raw wood, but linseed oil as a finish doesn't rank high on the durability scale. Wood finished in linseed oil is prone to scratching and water damage. This is exaggerated if the finish isn't maintained and regularly recoated, at least once per year.
Best for Durability and Maintenance: Tung Oil
While both tung oil and linseed oil require maintenance and regular re-coating for peak durability, tung oil is far more water-resistant and scratch-resistant than linseed oil. That said, modern varnishes and top coats will offer more durability than both oils.
Pure tung oil is easy to apply and nearly impossible to mess up. Simply sand the wood until smooth, remove all dust and debris, then flood the surface with the oil. As you see dry spots occur, add more oil. Once the wood no longer absorbs any oil, wipe the surface clean with a dry cloth. Allow the oil to cure for several days, then lightly sand and re-coat. Five, six, seven, or more coats can be applied.
Applying raw linseed oil is similar to tung oil, with some slight differences. After sanding the wood and removing the dust and debris, liberally wipe the linseed oil on the wood following the grain until the entire surface has been covered. Allow the oil to penetrate the wood for 15 minutes, then wipe off the excess. If the surface has dried considerably over 15 minutes, allow the wood to absorb more oil for another 15 minutes before wiping clean.
Apply a minimum of three coats, allowing several weeks of cure time between coats and buffing with grade 0000 steel wool between coats.
Best for Application: Tung Oil
Not only is tung oil possibly the easiest wood finish to apply, but the several weeks between coats of raw linseed oil also makes it an impractical finish option for many people. Boiled linseed oil and polymerized linseed oil will cut down on the curing time, but keep in mind that these oils have different qualities and safety levels.
Pure tung oil costs around $25 to $30 per quart, while impure versions of tung oil with additives can be found for lower prices.
A quart of raw linseed oil will run you less than $20, while popular alternatives such as boiled linseed oil can be found for as low as $13 per quart.
Best for Cost: Linseed Oil
Raw linseed oil is almost always less expensive than pure tung oil, while popular alternatives and impure versions are more competitively priced.
While no tung oil finish will stay in perfect condition forever, the finish on items kept inside away from sun and water exposure will last much longer than those left outside. Pay close attention to the surface's water beading capabilities as well as the richness of the finish, and reapply once the wood looks dried and lackluster.
Linseed oil should be reapplied at least once a year, sometimes multiple times a year depending on the volume of use the surface sees. Because linseed oil isn't recommended for outdoor use, it should never see regular sun or water exposure.
Best for Lifespan: Tied
Both tung oil and linseed oil (like most oil finishes) need regular reapplication to look their best and offer the most protection. Additionally, both oils will need more regular reapplication depending on the amount of use the finished surface sees.
When it comes to comparing pure tung oil and raw linseed oil, tung oil beats linseed oil on nearly every front. The appearance is generally better and less yellowed, it's easier to maintain, more durable, and takes drastically less time to apply. However, if cost is a factor, raw linseed oil is cheaper than pure tung oil and still makes for a quality natural finish, especially if you prefer satin over matte.
Juita, Dlugogorski BZ, Kennedy EM, Mackie JC. Low temperature oxidation of linseed oil: a review. Fire Science Reviews. 2012;1(1):3.